Brother LH4-B800E Service manual

LH4-B800E
SERVICE MANUAL
Please read this manual before making any adjustments.
ELECTRONIC LOCKSTITCH BUTTON HOLER
Thank you very much for buying a BROTHER sewing machine. Before using your new machine, please read the safety instructions below and the explanations given in the instruction manual.
With industrial sewing machines, it is normal to carry out work while positioned directly in front of moving parts such as the
needle and thread take-up lever, and consequently there is always a danger of injury that can be caused by these parts. Follow
the instructions from training personnel and instructors regarding safe and correct operation before operating the machine so
that you will know how to use it correctly.
SAFETY INSTRUCTIONS
1. Safety indications and their meanings
This instruction manual and the indications and symbols that are used on the machine itself are provided in order to ensure safe
operation of this machine and to prevent accidents and injury to yourself or other people.
The meanings of these indications and symbols are given below.
Indications
DANGER
The instructions which follow this term indicate situations where failure to follow the instructions will almost certainly result in death or severe injury.
CAUTION
The instructions which follow this term indicate situations where failure to follow the instructions could cause injury when using the machine or physical damage to equipment and
surroundings
Symbols
................ This symbol (
) indicates something that you should be careful of. The picture inside the triangle indicates the nature of the caution that must be taken.
(For example, the symbol at left means “beware of injury”.)
................ This symbol (
) indicates something that you must not do.
................ This symbol ( ● ) indicates something that you must do. The picture inside the circle indicates the nature of
the thing that must be done.
(For example, the symbol at left means “you must make the ground connection”.)
LH4-B800E
i
2. Notes on safety
DANGER
Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before
opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.
CAUTION
Environmental requirements
Use the sewing machine in an area which is free from
sources of strong electrical noise such as highfrequency welders.
Sources of strong electrical noise may cause problems
with correct operation.
Any fluctuations in the power supply voltage should
be within ±10% of the rated voltage for the machine.
Voltage fluctuations which are greater than this may
cause problems with correct operation.
The power supply capacity should be greater than the
requirements for the sewing machine's electrical consumption.
Insufficient power supply capacity may cause problems
with correct operation.
The ambient temperature should be within the range
of 5°C to 35°C during use.
Temperatures which are lower or higher than this may
cause problems with correct operation.
The relative humidity should be within the range of 45%
to 85% during use, and no dew formation should occur
in any devices.
Excessively dry or humid environments and dew formation may cause problems with correct operation.
Avoid exposure to direct sunlight during use.
Exposure to direct sunlight may cause problems with
correct operation.
In the event of an electrical storm, turn off the power
and disconnect the power cord from the wall outlet.
Lightning may cause problems with correct operation.
Installation
Machine installation should only be carried out by a
qualified technician.
Contact your Brother dealer or a qualified electrician
for any electrical work that may need to be done.
The sewing machine weighs more than 56 kg. The
installation should be carried out by two or more people.
Do not connect the power cord until installation is
complete, otherwise the machine may operate if the
treadle is pressed by mistake, which could result in
injury.
Use both hands to hold the machine head when tilting
it back or returning it to its original position. If only one
hand is used, the weight of the machine head may
cause your hand to slip, and your hand may get caught.
Be sure to connect the ground. If the ground connection is not secure, you run a high risk of receiving a
serious electric shock, and problems with correct
operation may also occur.
ii
LH4-B800E
All cords should be secured at least 25 mm away from
any moving parts. Furthermore, do not excessively
bend the cords or secure them too firmly with staples,
otherwise there is the danger that fire or electric shocks
could occur.
Install the belt covers to the machine head and motor.
If using a work table which has casters, the casters
should be secured in such a way so that they cannot
move.
Be sure to wear protective goggles and gloves when
handling the lubricating oil and grease, so that they do
not get into your eyes or onto your skin, otherwise inflammation can result.
Furthermore, do not drink the oil or eat the grease under any circumstances, as they can cause vomiting
and diarrhoea.
Keep the oil out of the reach of children.
CAUTION
Sewing
This sewing machine should only be used by operators who have received the necessary training in safe
use beforehand.
If using a work table which has casters, the casters
should be secured in such a way so that they cannot
move.
The sewing machine should not be used for any
applications other than sewing.
Attach all safety devices before using the sewing
machine. If the machine is used without these devices
attached, injury may result.
Be sure to wear protective goggles when using the
machine.
If goggles are not worn, there is the danger that if a
needle breaks, parts of the broken needle may enter
your eyes and injury may result.
Turn off the power switch at the following times,
otherwise the machine may operate if the treadle is
pressed by mistake, which could result in injury.
• When threading the needle
• When replacing the needle and bobbin
• When not using the machine and when leaving the
machine unattended
Do not touch any of the moving parts or press any
objects against the machine while sewing, as this may
result in personal injury or damage to the machine.
If an error occurs in machine, or if abnormal noises or
smells are noticed, immediately turn off the power
switch. Then contact your nearest Brother dealer or a
qualified technician.
If the machine develops a problem, contact your
nearest Brother dealer or a qualified technician.
Cleaning
Turn off the power switch before carrying out cleaning,
otherwise the machine may operate if the treadle is
pressed by mistake, which could result in injury.
Be sure to wear protective goggles and gloves when
handling the lubricating oil and grease, so that they do
not get into your eyes or onto your skin, otherwise inflammation can result.
Furthermore, do not drink the oil or eat the grease under any circumstances, as they can cause vomiting
and diarrhoea.
Keep the oil out of the reach of children.
Maintenance and inspection
Maintenance and inspection of the sewing machine
should only be carried out by a qualified technician.
Ask your Brother dealer or a qualified electrician to
carry out any maintenance and inspection of the
electrical system.
Turn off the power switch and disconnect the power
cord from the wall outlet at the following times,
otherwise the machine may operate if the treadle is
pressed by mistake, which could result in injury.
• When carrying out inspection, adjustment and maintenance
• When replacing consumable parts such as the rotary
hook
Turn off the power switch before inserting or removing
the plug, otherwise damage to the control box could
result.
LH4-B800E
If the power switch needs to be left on when carrying
out some adjustment, be extremely careful to observe
all safety precautions.
Use both hands to hold the machine head when tilting
it back or returning it to its original position. If only one
hand is used, the weight of the machine head may
cause your hand to slip, and your hand may get caught.
Use only the proper replacement parts as specified by
Brother.
If any safety devices have been removed, be absolutely sure to re-install them to their original positions
and check that they operate correctly before using the
machine.
Any problems in machine operation which result from
unauthorized modifications to the machine will not be
covered by the warranty.
iii
3. Warning labels
The following warning labels appear on the sewing machine.
Please follow the instructions on the labels at all times when using the machine. If the labels have been removed or are difficult to read, please contact your nearest Brother dealer.
1
Hazardous voltage
will cause injury.
Hochspannung
verletzungsgefahr!
Turn off main
switch and wait 5
minutes before
opening this cover.
Bitte schalten sie den Eteindrel'interrupteur et
hauptschalter aus und attendre 5 minutes
warten sie 5 minuten, avantd' ouvrir le capot
bevor sie diese
abdeckung öffnen.
2
Moving parts
may cause injury.
Operate with safety devices.
Turn off main switch before
threading, changing bobbin
and needle, cleaning etc.
3
Un voltage non adapté
provoque des blessures.
Un voltaje inadecuado
puede provocar las
heridas.
Apagar el interruptor
principal y esperar 5
minutos antes de abrir
esta cubierta.
Safety devices
Eye guard
Finger guard
Thread take-up cover
Belt cover
Belt cover plate, etc.
Be sure to connect the ground. If the ground connection is not secure, you run a high risk of
receiving a serious electric shock, and problems with correct operation may also occur.
4
Do not touch any of the cutter or press any objects against the machine while sewing, as this may
result in personal injury or damage to the machine.
5
Do not touch any of the fan or press any objects against the machine, as this 5may result in
personal injury or damage to the machine.
Thread take-up cover
Belt cover
r
Eyeguard
e
t
Belt cover plate
Finger guard
w
iv
e
LH4-B800E
q
CONTENTS
1. MECHANISM DESCRIPTION .......................................... 1-1
1-1.
1-2.
1-3.
1-4.
1-5.
1-6.
1-7.
1-8.
1-9.
1-10.
1-11.
Needle take-up mechanism ............................................... 1-1
Upper shaft, lower shaft and rotary hook mechanism ....... 1-2
Needle zigzag mechanism ................................................. 1-3
Presser foot lifter mechanism ............................................ 1-4
Feed mechanism ............................................................... 1-5
Cutter mechanism .............................................................. 1-6
Thread breakage detection mechanism ............................ 1-7
Lubrication mechanism ...................................................... 1-8
Tension release mechanism ............................................ 1-10
Upper thread trimmer mechanism ................................... 1-12
Lower thread trimmer mechanism ................................... 1-16
2. DISASSEMBLY ................................................................ 2-1
2-1.
2-2.
2-3.
2-4.
2-5.
2-6.
2-7.
2-8.
2-9.
2-10.
2-11.
2-12.
2-13.
2-14.
2-15.
Lower shaft and idle pulley mechanism ............................. 2-1
Lower thread trimmer assembly ........................................ 2-2
Feed mechanism ............................................................... 2-4
Bobbin presser mechanism ............................................... 2-7
Tension release mechanism .............................................. 2-8
Presser lifter mechanism ................................................. 2-10
Needle zigzag mechanism ............................................... 2-13
Cutter mechanism ............................................................ 2-14
Upper shaft and tension pulley mechanism ..................... 2-16
Needle bar and thread take-up mechanism ..................... 2-17
Presser bar mechanism ................................................... 2-19
Upper thread trimmer mechanism ................................... 2-20
Thread breakage detection mechanism .......................... 2-22
Lubrication mechanism .................................................... 2-23
Rotary hook mechanism .................................................. 2-29
3. ASSEMBLY ...................................................................... 3-1
3-1.
3-2.
3-3.
3-4.
3-5.
3-6.
3-7.
3-8.
3-9.
3-10.
3-11.
3-12.
3-13.
3-14.
3-15.
Lower shaft and idle pulley mechanism ............................. 3-1
Lower thread trimmer mechanism ..................................... 3-2
Feed mechanism ............................................................... 3-4
Bobbin presser mechanism ............................................... 3-7
Tension release mechanism .............................................. 3-8
Presser lifter mechanism ................................................. 3-10
Needle zigzag mechanism ............................................... 3-13
Cutter mechanism ............................................................ 3-14
Upper shaft and tension pulley mechanism ..................... 3-17
Needle bar and thread take-up mechanism ..................... 3-18
Presser bar mechanism ................................................... 3-20
Upper thread trimmer mechanism ................................... 3-21
Thread breakage detection mechanism .......................... 3-23
Lubrication mechanism .................................................... 3-24
Rotary hook mechanism .................................................. 3-31
LH4-B800E
4. ADJUSTMENT ....................................................................................................... 4-1
4-1.
4-2.
4-3.
4-4.
4-5.
4-6.
4-7.
4-8.
4-9.
4-10.
4-11.
4-12.
4-13.
4-14.
4-15.
4-16.
4-17.
4-18.
4-19.
4-20.
4-21.
4-22.
4-23.
4-24.
Adjusting the needle zigzag home position sensor position ....................................... 4-2
Adjusting the feed home position sensor position ...................................................... 4-3
Adjusting the presser foot home position sensor position .......................................... 4-5
Adjusting the needle bar height .................................................................................. 4-6
Adjusting the needle and rotary hook timing ............................................................... 4-6
Adjusting the inner rotary hook and rotary hook holder overlap ................................. 4-8
Adjusting the presser foot pressure ............................................................................ 4-8
Adjusting the work clamp lift amount .......................................................................... 4-8
Adjusting the work clamp lateral position .................................................................... 4-9
Adjusting the knife home position sensor position ...................................................... 4-9
Adjusting the knife installation position ..................................................................... 4-10
Adjusting the cutter installation height ...................................................................... 4-11
Adjusting the upper thread trimming ......................................................................... 4-12
Adjusting the lower thread trimming ......................................................................... 4-19
Adjusting the bobbin presser .................................................................................... 4-23
Adjusting the thread breakage detector .................................................................... 4-24
Adjusting the thread tension at the tack tension control ........................................... 4-25
Adjusting the thread tension at the zigzag tension control ....................................... 4-25
Adjusting the upper thread feeding amount .............................................................. 4-26
Adjusting the feed timing belt .................................................................................... 4-26
Adjusting the upper shaft timing belt ......................................................................... 4-27
Adjusting the rotary hook lubrication ......................................................................... 4-27
Adjusting the needle up stop position ....................................................................... 4-28
Adjusting the V-belt tension ...................................................................................... 4-28
5. TROUBLESHOOTING GUIDE ............................................................................... 5-1
5-1.
5-2.
5-3.
5-4.
5-5.
5-6.
5-7.
5-8.
5-9.
5-10.
5-11.
5-12.
5-13.
5-14.
5-15.
5-16.
5-17.
5-18.
5-19.
Needle thread breakage ............................................................................................. 5-1
Skipped stitches .......................................................................................................... 5-3
Uneven seams 1)......Beginning of sewing (1) ............................................................ 5-4
Uneven seams 2)......Around rear tack or front tack ................................................... 5-6
Uneven seams 3)......Loose thread end at end backtack (1) ...................................... 5-6
Uneven seams 4)......Sticking in needle plate ............................................................. 5-6
Uneven seams 5)......All stitches ................................................................................ 5-7
Needle thread runout .................................................................................................. 5-8
Unraveling of thread trimmed by upper thread trimmer assembly ............................ 5-10
Needle thread mis-trimming ...................................................................................... 5-10
Needle strikes upper thread trimmer ........................................................................ 5-11
Needle breakage ...................................................................................................... 5-12
(1)Imperfect cutter function (imperfect material cutting) ........................................... 5-13
Needle thread mis-winding ....................................................................................... 5-14
Folding clamp is not raised (1) Pulse motor stepping sound cannot be heard ......... 5-15
Lower thread is not trimmed (pulls when material is removed) ................................ 5-17
Feed mechanism does not operate or motor is out of step ...................................... 5-17
Needle does not zigzag or noise occurs when needle zigzags ................................ 5-18
Sewing machine stops during sewing ....................................................................... 5-18
6. ELECTRIC MECHANISM ....................................................................................... 6-1
6-1.
6-2.
6-3.
6-4.
6-5.
6-6.
6-7.
6-8.
6-9.
Precautions at the time of adjustment ........................................................................ 6-1
Components inside the control box and the operation panel ...................................... 6-2
Fuse explanation ........................................................................................................ 6-3
Connectors ................................................................................................................. 6-4
Description of DIP switches ...................................................................................... 6-22
Description of machine motor parameters ................................................................ 6-26
Error code table ........................................................................................................ 6-27
Troubleshooting ........................................................................................................ 6-29
Control circuit block diagram .................................................................................... 6-34
LH4-B800E
1. MECHANISM DESCRIPTION
1. MECHANISM DESCRIPTION
1-1. Needle take-up mechanism
Direction of
rotation
w
!0
e
q
!3
r
u
t
o
!2
i
y
!1
1. When the machine pulley q is turned in the direction of the arrow, the rotation is transmitted to the thread take-up
crank e that is secured to the end of the upper shaft w.
2. The needle bar crank r is secured to the thread take-up crank e, and it transmits vertical motion to the needle
bar clamp u via the needle bar crank rod t and needle bar bracket slide rod y.
At this time, the needle bar crank rod t moves together with the crank rod guide o via the needle bar bracket
slide rod i. (It moves along the slot in the needle hole of the thread take-up !0 by means of the needle bar crank
r.)
3. The needle bar !1 is secured to the needle bar clamp u, and it moves smoothly up and down while being guided
by the bushings at the top and bottom of the needle bar guide !2 and needle bar bracket !3.
LH4-B800E
1-1
1. MECHANISM DESCRIPTION
1-2. Upper shaft, lower shaft and rotary hook mechanism
r
e
w
Direction of
rotation
q
y
i
u
t
1. When the machine pulley q is turned in the direction of the arrow, the rotation is transmitted to timing pulley U e
that is secured to the upper shaft w.
2. The timing belt r is attached to timing pulley U e, and it accurately transmits the rotation of the upper shaft to the
timing pulley t.
3. The timing pulley t is secured to the lower shaft y, and it transmits the rotation to the rotary hook joint u that is
secured to the end of the lower shaft y.
4. The rotary hook i is secured to the rotary hook joint u and rotates fully together with the rotary hook joint u.
1-2
LH4-B800E
1. MECHANISM DESCRIPTION
1-3. Needle zigzag mechanism
q
w
y
r
e
t
1. The operation of the pulse motor q is transmitted as reciprocal motion to the zigzag lever e via the zigzag
connecting rod w.
2. The zigzag lever e is secured to the zigzag lever F assembly r, and causes the needle bar bracket slide block t
that is linked onto the end of the zigzag lever F assembly r to move in a reciprocal motion.
3. The needle bar bracket slide block t is linked to the groove in the needle bar bracket y and causes the needle
bar bracket y to move in a reciprocal motion.
LH4-B800E
1-3
1. MECHANISM DESCRIPTION
1-4. Presser foot lifter mechanism
u
t
r
i
e
q
o
!0
w
!1
y
!2
!3
!4
!5
1. When the pulse motor q operates, the gear w that is installed to the pulse motor shaft engages with the presser
driving arm e so that the guide bracket r moves along the guide shaft t and moves the presser driving arm e
up and down.
2. The presser driving arm e causes the presser foot lifter connecting rod y to move up and down.
3. The movement of the presser foot lifter connecting rod y is transmitted via the knee lifter lever u, upper thread
trimmer driving link i and knee lifter lever o to move the presser bar guide bracket assembly !0 up and down.
4. The feed arm !1 is secured to the presser bar guide bracket assembly !0, and it moves the presser roller bracket
!2 that is secured to the bottom edge of the feed arm !1 up and down.
5. Feed arm support !4 that is connected to the feed arm !3 is hooked onto the presser roller bracket !2, and it
moves the work clamp !5 up and down.
1-4
LH4-B800E
1. MECHANISM DESCRIPTION
1-5. Feed mechanism
i
t
y
!0
o
u
e
r
q
w
1. A timing belt r is attached to pulley A w that is secured to the pulse motor q and to pulley B e, and this timing
belt r transmits the motion from the pulse motor q.
2. The feed arm support t is secured to the timing belt r. The feed arm support t moves back and forth while
being guided by feed guide shaft A y and feed guide shaft B u.
3. The feed arm i is connected to the feed arm support t, and it moves the work clamp o that is installed to the
feed arm i and the length feed plate !0 that is installed to the feed arm support t back and forth.
LH4-B800E
1-5
1. MECHANISM DESCRIPTION
1-6. Cutter mechanism
e
t
u
w
y
q
r
1. When a cutter ON signal is input, the cutter solenoid q operates.
2. A cutter link bracket w is secured to the end of the plunger, and it turns the cutter driving arm r via the cutter
driving link e.
3. The cutter driving link t that is secured to the end of the cutter driving arm r is moved up and down.
4. The driving shaft holder assembly y is linked to the cutter driving link t, and this causes the cutter driving shaft
u that is connected to the driving shaft holder assembly y to move up and down.
1-6
LH4-B800E
1. MECHANISM DESCRIPTION
1-7. Thread breakage detection mechanism
e
q
w
r
1. The cutter bar fixed plate assembly q and the thread guide w are secure to the thread breakage perceiving shaft
e. When a thread breakage occurs, the cutter bar fixed plate assembly q drop by its own weight and moves the
thread guide w in the direction of the arrow.
2. When the sensor r detects the cutter bar fixed plate assembly q, the sewing machine stops and the cutter is
prevented from dropping.
LH4-B800E
1-7
1. MECHANISM DESCRIPTION
1-8. Lubrication mechanism
!1
!5
!4
r
!8
!6
o
t
@0
u
y
(C)
!7
!2
!3
i
(D)
!9
!0
@3
@2
(B)
@1
w
(E)
(D)
(A)
(B)
q
(A)
e
1. The plunger pump w that is attached to the lower shaft q draws oil up (A) through the pump filter e and sends
the oil (B) to the oil terminal r, where the wick lubricates the felt t.
2. The oil is transferred from the felt t by means of the wick to the following places.
1) Oil is supplied to bush F y, and it passes through the upper shaft u and thread take-up crank i to the needle
bar crank o. Furthermore, oil is supplied from bush F y to zigzag lever bush F !0.
2) Oil is supplied from the needle bar bracket support shaft !1 to the needle bar !2, and from there it is supplied
to parts such as the needle bar clamp !3.
3) Oil is supplied from the support shaft !4 to the thread take-up !5.
4) Oil is supplied to bush M !6.
5) Oil is supplied to zigzag lever bush R !7.
6) Oil is supplied to the motor lever shaft !8, and from there it is supplied to the zigzag connecting rod shaft !9.
(Oil which splatters inside the arm is collected by the felt @0 and is supplied to the crank rod guide @1 and to the
slide block @2.)
3. The oil which is sent to the oil terminal r is returned to the oil tank via the oil return tube (C).
4. The oil which collects in the jaw of the arm, is absorbed by the felt @3 and is drawn up by the plunger pump w
through the tube (D), and it is then returned to the oil tank (E) by the plunger pump w.
1-8
LH4-B800E
1. MECHANISM DESCRIPTION
1-8-1. Lower shaft and rotary hook lubrication
q
w
u
e
y
o
r
t
!0
More
Less
i
1. The oil which is drawn up by the wick q is supplied to the lower shaft w.
2. The oil which is drawn up by the wick e passes through the felt r and the rotary hook joint t to the felt y, where
it is supplied to the rotary hook u.
3. The oil that is supplied to the rotary hook u can be adjusted by turning the screw i to vary the amount by which
the rubber presser o presses down on the collar !0 that the wick passes through.
LH4-B800E
1-9
1. MECHANISM DESCRIPTION
1-9. Tension release mechanism
[Zigzag tension control]
q
w
r
e
t
y
4 3
1
0
2
u
1. When a thread tension ON signal is input, the tension release solenoid q operates.
2. The plunger w moves in the direction of the arrow, and the movement is transmitted to the tension release
solenoid link e that is connected to the plunger w.
3. The tension release link r that is connected to the tension release solenoid link e operates with the shoulder
screw t as a pivot and presses against the tension release pin y.
4. The tension release pin y presses against the tension disc presser u to release the tension discs.
1 - 10
LH4-B800E
1. MECHANISM DESCRIPTION
[Tack tension control]
i
t
r
o
u
e
!2
!0
!1
!4
2
!3
4 3
1
0
q
w
y
1. When the pulse motor q operates, the gear w that is installed to the pulse motor shaft engages with the presser
driving arm e so that the guide bracket r moves along the guide shaft t and moves the presser driving arm e
in the direction of the arrow.
2. The presser driving arm e causes the presser foot lifter connecting rod y to move in the direction of the arrow.
3. The movement of the presser foot lifter connecting rod y is transmitted via the knee lifter lever u to move the
upper thread trimmer driving link i in the direction of the arrow.
4. The needle roller !0 that is secured to the end of the tension release driving lever o is linked to the cam groove of
the upper thread trimmer driving link i, so that when the upper thread trimmer driving link i operates, the
tension release driving lever o that is secured to the tension release shaft !1 moves in the direction of the arrow.
5. The tension release cam !2 is secured to the end of the tension release shaft !1, and so the tension release cam
!2 moves in the direction of the arrow.
6. When the tension release cam !2 presses against the tension release pin !3, the tension release pin !3 presses
against the tension disc presser !4 to release the tension discs.
LH4-B800E
1 - 11
1. MECHANISM DESCRIPTION
1-10. Upper thread trimmer mechanism
Upper thread trimmer mechanism operating sequence
(8) The presser foot drops.
(1) Sewing starts (machine
starts)
(7) The upper thread scissors retract and the presser foot lifts.
Presser foot
drops
Presser foot
lifts
(2) After 1.5--2.5 mm of feed, the upper
thread scissors gradually start to
open.
(6) The upper thread is
clamped and cut.
(4)(3)
(2)(1)(8)
(5)
(6)
(7)
1 - 12
(4) Sewing ends.
(5) The upper thread scissors move forward.
Upper thread trimming
(3) After approximately 4.6 mm of feed,
the upper thread scissors are fully
pen.
LH4-B800E
1. MECHANISM DESCRIPTION
!1
!3
!4
u
o
!2
r
!0
i
t
!5
e
!6
@1
!8
!9
!7
@0
w
q
@2
@3
y
1.
2.
3.
4.
5.
6.
7.
8.
9.
When the pulse motor q operates, the gear w that is installed to the pulse motor shaft engages with the presser driving arm e so that the
guide bracket r moves along the guide shaft t and moves the presser driving arm e in the direction of the arrow.
The presser driving arm e causes the presser foot lifter connecting rod y to move in the direction of the arrow.
The movement of the presser foot lifter connecting rod y is transmitted via the knee lifter lever u to move the upper thread trimmer driving
link i in the direction of the arrow.
The driving lever roller !3 and ball bearing !4 that are installed to the ends of the trimmer driving levers o and !0 by the shoulder screws !1
and !2 are linked to the cam groove in the upper thread trimmer driving link i so that when the upper thread trimmer driving link i moves
in the direction of the arrow, the trimmer driving levers o and !0 operate.
When the trimmer driving levers o and !0 operate, the longitudinal feed arm !5 and trimmer driving arm !6 that are secured to the trimmer
driving levers o and !0 move in the direction of the arrow.
When the longitudinal feed arm !5 operates, the upper thread trimmer lever !8 that is attached to the longitudinal feed arm roller !7 at the end
of the longitudinal feed arm !5 moves back and forth.
When the trimmer driving arm !6 operates, the driving arm roller !9 that is installed to the trimmer driving arm !6 rolls along the cam groove
in the upper thread trimmer lever !8, and the upper thread trimmer lever !8 rotates centering on the upper thread trimmer fulcrum shaft @0.
The setting plate @1 is secured to the end of the upper thread trimmer lever !8, and so the movement is transmitted to the upper thread
trimmer assembly @2 that is secured to the setting plate @1.
Upper thread trimmer M @3 that is installed to the upper thread trimmer assembly @2 comes into contact with the work clamp, so that upper
thread trimmer M @3 closes and cuts the thread.
LH4-B800E
1 - 13
1. MECHANISM DESCRIPTION
r
r
e
e
Figure B
Figure A
D
C
t
q
w
e
r
1. An opening cam e is attached to the opening cam bracket w that is secured to the feed arm q (Figure A). After
sewing starts, the feed arm q moves in the direction of the arrow (forward).
2. When upper thread trimmer M r touches against the ridge line on the opening cam e, the upper thread trimmer
gradually starts to open (Figure B). At this time, section D of the opening cam e fits into the upper thread trimmer
assembly t so that the upper thread trimmer assembly t cannot move in the direction of arrow C.
1 - 14
LH4-B800E
1. MECHANISM DESCRIPTION
q
t
e
w
u
Figure A
i
r
y
Figure B
i
y
r
t
e
u
w
q
3. Then, when the feed mechanism moves forward, the cam w that is secured to the feed arm q moves in the
direction of the arrow (forward) and moves the back plate e in the direction of the arrow (forward).
4. When the back plate e and the stop plate r lock together and clamp the upper thread trimmer lever t and the
stop plate r separates from the back stopper y, the upper thread trimmer lever t is pulled in the direction of the
arrow by the spring u, and the upper thread trimmer assembly i changes from the condition in Figure A to the
one in Figure B and the upper thread trimmer opens fully.
LH4-B800E
1 - 15
1. MECHANISM DESCRIPTION
1-11. Lower thread trimmer mechanism
t
r
e
q
y
w
!0
u
o
i
1. When the pulse motor q operates, the gear w that is installed to the pulse motor shaft engages with the presser
driving arm e so that the guide bracket r moves along the guide shaft t and moves the presser driving arm e
in the direction of the arrow.
2. The presser driving arm e causes the presser foot lifter connecting rod y to move in the direction of the arrow.
3. The presser foot lifter connecting rod y is connected to the lower thread trimmer cam lever u, so that the lower
thread trimmer cam lever u moves.
4. The roller i that is installed to the end of the lower thread trimmer cam lever u is linked to the cam groove in the
lower thread trimmer cam o, so that when the lower thread trimmer cam lever u operates, the lower thread
trimmer cam moves with it and the movement is transmitted to the lower thread trimmer cam connecting rod !0
that is connected to the lower thread trimmer cam o.
1 - 16
LH4-B800E
1. MECHANISM DESCRIPTION
i
u
t
y
r
r
i
q
e
!1
o
!0
!3
w
!4
!2
r
5. The lower thread trimmer cam connecting rod q is connected to lower thread trimmer link A w, so that the
movement of the lower thread trimmer cam connecting rod q is transmitted via lower thread trimmer link A w and
the lower thread trimmer connecting rod e to the knife driving lever r.
6. The collar y that is installed to the lever t is linked to the cam groove in the knife driving lever r, so that when
the knife driving lever r operates, the lever t rotates centering on the screw u.
7. The lower thread retainer i is secured to the lever t, so the lower thread retainer i starts to operate.
8. When the lower thread retainer i operates, the collar !0 that is installed to the lower thread clamp plate o moves
over the ridge line of the cam of the lower thread retainer i, and the lower thread retainer i starts to close and
engages with the lower thread presser !1 so that the lower thread is clamped.
9. The lower thread retainer i then continues operating.
10. The fixed knife !2 is secured to the knife driving lever r, so that when the knife driving lever r operates, the cam
section of the movable knife !3 that is secured to the fixed knife !2 moves over the cam section of the base plate
!4 so that the movable knife !3 starts to close. When the lower thread retainer i has finished operating, the
movable knife !3 meshes fully with the fixed knife !2 and cuts the lower thread.
LH4-B800E
1 - 17
1. MECHANISM DESCRIPTION
o
t
y
q
r
i
u
e
w
11. When feed guide shaft B q that is secured to the feed arm support moves forward after sewing starts, the roller r
that is secured to the opening plate w by means of the roller shaft e moves over feed guide shaft B q and the
opening plate w rotates centering on the shoulder screw t.
12. The opening plate w presses against the collar u that is installed to the lower thread clamp y and the lower
thread clamp y rotates centering on the shoulder screw i, so that the clamped lower thread is released by the
lower thread presser o and the lower thread clamp y.
1 - 18
LH4-B800E
2. DISASSEMBLY
2. DISASSEMBLY
2-1. Lower shaft and idle pulley mechanism
q
w
t
r
u
y
e
!0
!1
o
i
Remove the two screws q, and then remove the cover w.
Loosen the set screw e, and then remove the set screw collar assembly r from the lower shaft t.
Loosen the set screw y, and then remove the timing pulley assembly u from the lower shaft t.
Loosen the two set screws i, and then remove the shaft o.
Remove the collar !0 and the idle pulley assembly !1.
LH4-B800E
2-1
2. DISASSEMBLY
2-2. Lower thread trimmer assembly
i
!1
!0
e
r
o
y
w
q
t
w
o
!7
!4
#1
u
!5
@1
@0
!9
!8
@8
@9
@6
#0
!6
@5
!4
@3
@4
@7
@2
!3
!2
Remove the screw q, and then remove the feed presser plate w.
Remove the bolt e and the washer r, and then remove the length feed plate t from the feed arm support y.
Remove the shoulder screw 4.37 u.
Remove the four screws i, and then remove the base plate o.
Remove the pan screw !0, and then remove the needle plate !1.
Remove the two screws !2, and then remove the fixed knife set !3 from the knife driving lever !4.
Remove the shoulder screw !5 and the screw !6, and then remove the lower thread presser !7 from the base plate o.
Remove the shoulder screw !8, plain washer !9 and spring washer @0, and then remove the lower thread clamp plate
assembly @1 from the base plate o.
Remove the shoulder screw @2, collar @3, washer U @4 and washer D @5, and then remove the knife driving lever !4
from the base plate o.
Remove the two screws @6, and then remove the lower thread retainer @7 from the lever assembly @8.
Remove the collar @9 and the screw #0, and then remove the lever assembly @8 from the base plate o.
Remove the screw #1.
2-2
LH4-B800E
2. DISASSEMBLY
w
e
@1
@0
q
!9
t r y
@2
t
u
@4
@3
@1
i
o
!0
!8
y
!1
!1
!6
!8
!7
!4
@5 !7
!5
!3 !4
!5
!6
@7
@6
!3
Remove the plate spring q.
Remove the shoulder screw w, and then remove the opening plate assembly e.
Remove the shoulder screw r.
Remove the shoulder screw u, and then remove the lower thread trimmer link assembly t.
Remove the bolt i, plain washer D o and spacer !0.
Loosen the set screw !3.
Remove the lower thread trimmer cam shaft !4, washer !5 and retaining ring !6.
Remove the lower thread trimmer cam lever !1.
Loosen the two set screws !9.
Remove the two lever shafts @0.
Remove the lower thread trimmer cam assembly @1 from the cover @2.
Remove the cover @2.
Remove the driving lever roller @3 and the shoulder screw @4, and then remove the lower thread trimmer cam connecting rod y from the lower thread trimmer cam !8.
Remove the retaining ring @5, and then remove the roller !7.
Remove the nut @6, and then remove the roller shaft @7 from the lower thread trimmer cam lever !1.
LH4-B800E
2-3
2. DISASSEMBLY
2-3. Feed mechanism
e
t
qw
y
!6 !8
@8
!8
@6
@7
!5
r
u
u
q
w
@9
!7
!8
!9
#1
#2
!7
#3
!1 !0
#0
@0
@1
i
o
#4
y
!7
@4
#5
!4
!3
t
!2
@5
r
@2
#8
#7 #6
@3
Remove the screw q and the plain washer w, and then remove the cord holder e and the cord support u.
Disconnect the cords for the feed pulse motor r, DC fan motor 40 assembly t and feed home position sensor y.
Remove the screw i and the plain washer o, and then remove the feed sensor support plate !0.
Remove the screw !1, and then remove the feed home position sensor y from the feed sensor support plate !0.
Remove the screw !2, and then remove the feed motor cover !3.
Remove the two screws !4, and then remove the DC fan motor 40 assembly t from the feed motor cover !3.
Remove the two bolts !5, and then remove the belt holder !6 from the feed arm support !7.
Loosen the bolt !9.
Remove the three screws @0 and the three plain washers @1.
Loosen the two set screws @2, and then remove the pulley A assembly @3.
Remove the four bolts @4, and then remove the motor mounting bracket @5 from the feed pulse motor r.
Loosen the set screw @6, and then remove the support shaft @8.
Remove the timing belt !8 and the pulley B assembly @7.
Remove the two ball bearings (688ZZNR) @9.
Loosen the set screw #1, and then remove feed guide shaft B #2 from the feed arm support !7.
Remove the two bolts #0.
Remove the feed arm support !7 and feed guide shaft A #3.
Remove the two retaining rings #4, and then remove the linear bush #5 from the feed arm support !7.
Remove the screw #6, and then remove the ball bearing stopper #7.
Remove the two feed shaft linear bushes #8.
2-4
LH4-B800E
2. DISASSEMBLY
q
e
w
t
r
r
t
i
u
y
o
For long-hole specifications (-5)
Remove feed guide shaft B-5 (for long-hole) q.
Remove feed guide shaft A-5 (for long-hole) w and feed arm support -5 (for long-hole) e.
Remove the two ball bearing stoppers B (for long-hole) r, and then remove the two linear bushes t.
Remove the screw y, and then remove the linear bush stopper plate (for long-hole) u.
Remove the linear bush 9.53 (for long-hole) i from the feed arm support -5 (for long-hole) o.
LH4-B800E
2-5
2. DISASSEMBLY
q
!4
w
!6
!2
!5
r
e
u
r
!3
!2
!1
t
y
@2
@3
!7
!8
r
o
!9
@4
!0
i
!0
Remove the two screws q, and then remove the feed arm support w and the opening cam assembly e from the feed
arm assembly r.
Remove the shoulder screw t, and then remove the work clamp y and the spring u from the feed arm assembly r.
Loosen the set screw i, and then remove the feed arm assembly r and feed arm support shaft o from the feed arm
support !0.
Remove the two eye bolts !1 and the two plain washers !2, and then remove the support plate !3 from the feed arm
!4.
Remove the two eye bolts !5 and the two plain washers !2, and then remove the cam !6 from the support plate !3.
Remove the eye bolt !7 and the flat washer !8, and then remove the feed cover !9 from the feed arm support !0.
Remove the two eye bolts @2 and the two spring washers @3, and then remove the length feed plate @4 from the feed
arm support !0.
2-6
LH4-B800E
2. DISASSEMBLY
2-4. Bobbin presser mechanism
!0
w
t
q
r
u
i
e
!2
!3
y
o
!0
!1
Remove the two extension springs q.
Remove the shoulder screw w, and then remove the opening plate e from the rotary hook cover r.
Remove the shoulder screw t, and then remove the bobbin presser bracket y and the auxiliary plate u.
Remove the shoulder screw i, and then remove the auxiliary plate u and the opening plate e.
Loosen the set screw o, and then remove the bobbin presser !0 from the bobbin presser bracket y.
Remove the screw !1 and the nut !2.
Remove spring hook U !3.
LH4-B800E
2-7
2. DISASSEMBLY
2-5. Tension release mechanism
o
!2
!8
e
!0
w
!3
4 3
1
0
2
!2
!0
!1
q
y
r
u
!5
!6
!8
t
i
!4
!1
!7
t
Loosen the screw q.
Remove the tension stud bracket assembly w and the tension release pin e.
Remove the shoulder screw r.
Remove the two screws u, and then remove the tension release solenoid assembly y.
Remove the shoulder screw i, and then remove the tension release link t.
Remove the bolt o, and then remove the plate !0, plunger !1 and spring !2.
Remove the plunger pin !3, and then remove the plunger !1 and the tension release solenoid link !5.
Remove the two screws !6, and then remove the tension release solenoid !7 from the solenoid holder !8.
2-8
LH4-B800E
2. DISASSEMBLY
y
r
!5
@2
!3
!4 !1
!9
0
1
!8
@0
@1
0
o
4 3
i
1
!2
!7
4 3
w
!0
2
q
e
2
!6
u
@4
@6
@3
@7
@5
@8
t
#2
!5
#4
#1
#0
@9
@5
#3
#5
Remove the shoulder screw q, and then remove the tension release lever w and the spring e.
Remove the tension stud assembly r from the tension release lever bracket y.
Remove the tension nut u, and then remove the spring i and washer o from the tension stud !0.
Remove the collar !1, and then remove the tension discs !2, tension disc presser !3 and tension disc presser !4 from
the tension stud !0.
Remove the sub thread tension assembly !5 and tension release pin !6 from the arm.
Remove the two tension discs !6, tension disc presser !7, tension disc presser !8, tension adjusting spring !9, washer
@0 and tension nut @1 from the sub tension stud @2.
Remove the screw @3 and the washer @4, and then remove the thread take-up lever assembly @5 from the tension
release shaft @6.
Remove the shoulder screw @7, and then remove the washer @8 from the arm.
Remove the shoulder screw @9 and the washer #0, and then remove the lever #1 from the adjusting lever #2.
Remove the two shoulder screws #3, and then remove the adjusting lever #2 and the tension take-up lever #4 from the
lever link #5.
LH4-B800E
2-9
2. DISASSEMBLY
2-6. Presser lifter mechanism
!5
w
!8
!6
q
y
e
u
!7
t
!1
r
t
r
!9
!8
!0
!1
@0
i
o
!5
@2
@3
!6
!7
!8
!2
!4
!3
Remove the two screws q, and then remove the clamp sensor dog w from the upper thread trimmer driving link e.
Remove the screw r, and then remove the sensor t.
Remove the pan screw y, and then remove the clamp sensor plate u.
[Remove the zigzag connecting rod while referring to "Needle zigzag mechanism".]
Remove the four screws i and the screw o.
Remove the two positioning pins !0.
Remove the motor bracket assembly !1 from the top of the arm.
Loosen the set screw !2, and then remove the driving arm presser !3 and the washer !4.
Remove the four bolts !6, and then remove the presser driving arm !7 from the guide bracket !8.
Loosen the four set screws !9, and then remove the two guide shafts @0 and the guide bracket !8.
Remove the bolt !5, and then remove the bearing holder @1.
Remove the two linear ball bearings @2 from the guide bracket !8.
2 - 10
LH4-B800E
2. DISASSEMBLY
r
w
q
e
q
w
i
u
e
y
t
Remove the bolt q, and then remove the pulse motor N assembly (for needle zigzag) w and the pulse motor FT
assembly (for presser lifter) e from the motor bracket r.
Remove the set screw t, and then remove the gear 15.75 y from the pulse motor FT assembly (for presser lifter) e.
Remove the set screw u, and then remove the motor lever i from the pulse motor N assembly (for needle zigzag)
w.
LH4-B800E
2 - 11
2. DISASSEMBLY
!1
!6
w
!2 !3
!4
q
!5
e
@1
!8
!9
@0
e
yr
tr
@1
@4@3
@2
!6
@6
i
u
e
@5
o
!0
Loosen the eye bolt w, and then remove lifter shaft A q.
Remove the shoulder screw r, and then remove the ball bearing t and the driving lever roller y.
Remove the set screw u.
Remove the lifter shaft i, small plain washer 8 o and retaining ring E6 !0.
Loosen the set screws !1 and !2.
Remove the retaining ring !3, and then remove the tension release shaft !4, tension release cam !5 and tension
release driving lever !6.
Remove the shoulder screw @0, and then remove the presser lifter connecting rod set e and the lifter shaft assembly
@1.
Remove the two O-rings !8 and the two trimmer driving levers !9.
Remove the spacer @2, plain washer D @3 and bolt @4, and then remove the knee lifter lever @5 from the presser lifter
connecting rod assembly @6.
2 - 12
LH4-B800E
2. DISASSEMBLY
2-7. Needle zigzag mechanism
e
q
w
!2
!4
!3
!5
i
u
t
y
y
@2
r
!4
@0
w
!0
!1
Remove the screw q, and then remove the zigzag sensor plate w from the motor bracket e.
Loosen the set screw r, and then remove the motor lever shaft t, zigzag connecting rod y and washer u from the
motor lever i.
Remove the screw !0, and then remove the sensor !1 from the zigzag sensor plate w.
Remove the bolt !2.
Remove the thrust washer !3 and the zigzag lever !4, and then remove the zigzag lever F assembly !5.
Loosen the set screw @2, remove the zigzag connecting rod shaft @0 and then remove the zigzag lever !4 and the
zigzag connecting rod y.
LH4-B800E
2 - 13
2. DISASSEMBLY
2-8. Cutter mechanism
!4
u
y
!2
t
!7
e
r
!8
!8
o
w
q
!3
o
!6
!5
i
!6
!5
o
u
o
!1
!0
Remove the screw q, and then remove the cutter w from cutter holder DL e.
Remove the screw r, and then remove cutter holder DL e from cutter holder M t.
Remove the bolt y, and then remove cutter holder M t from the cutter holder u.
Remove the bolt i, and then remove the cutter holder u from the cutter driving shaft o.
Remove the screw !0, and then remove the knife sensor assembly !1.
Remove the spring !2 from the cutter driving arm assembly !3 and the tension release shaft !4.
Remove the nut !5, and then remove the adjusting screw assembly !6 from the arm.
Loosen the two set screws !7, and then remove the cutter driver shaft o.
Remove the oil rejector !8.
2 - 14
LH4-B800E
2. DISASSEMBLY
r
t
y
!1
w
!0
i
o
!6
@3
@4
@2
@6
@5
@0
!9
@6
t
!7
!5 !6
w
@8
@7
!4
@1
Loosen the bolt y.
Take out the solenoid plunger from the cutter solenoid w.
Remove the four screws r, and then remove the cutter solenoid bracket t.
Loosen the set screw @5.
Loosen the two set screws @6, and then remove the cutter driving arm shaft @7, from the set screw collar @8 and the
cutter driving arm assembly @2.
Remove the four screws @3, and then remove the cutter bar guide @4.
Remove the cutter driving arm assembly @2 from the arm.
Remove the cutter driving link !9, needle bar bracket slide block @0 and driving shaft holder assembly @1 from the
cutter driving arm assembly @2.
Remove the washer i and retaining ring E6 o, and then remove the cutter link bracket assembly !0 from the cutter
link shaft !1.
Remove the three bolts !4, and then remove the cutter solenoid w from the cutter solenoid bracket t.
Remove the spring washer !5 and the two nuts !6, and then remove the solenoid stopper !7 from the solenoid flange.
LH4-B800E
2 - 15
2. DISASSEMBLY
2-9. Upper shaft and tension pulley mechanism
q
q
!8
w
r
t
w
r
u
i
!1
!0
o
e
!4
!3 !5
!2
!8
!7
!6
!1
!2
u
!4
!9
!1
t y
Loosen the screw q, and then remove the pulley assembly w.
Remove the screw e, and then remove the synchronizer assembly H80 r from the arm.
Remove the two bolts t and the two plain washers y, and then remove the tension pulley assembly u.
Remove the screw i and the set screw o, and then remove the thread take-up crank !0 from the upper shaft
assembly !1.
Loosen the two set screws !2, and then remove the set screw collar assembly !3.
Loosen the two set screws !4, and then remove the bobbin winder pulley !5.
Loosen the set screw !6, and then remove the timing pulley U assembly !7.
Remove the timing belt !8.
Remove the bearing !9.
2 - 16
LH4-B800E
2. DISASSEMBLY
2-10. Needle bar and thread take-up mechanism
y
!3
e
u
t
@0
!4
w
r
!0
!2
!1
!6
!3
!5
!4
i
@3
!8
!7
o
!9 @0
!3
@1
@2
q
Remove the set screw w and nut e from the arm.
Remove the screw r, and then remove the stopper t from the arm.
Remove the set screw y and the nut u from the stopper t.
Remove the set screw @2, and then remove the needle bar thread guide q from the needle bar @1.
Loosen the set screw i, and then remove the needle bar thread guide o.
Loosen the set screw !0, and then remove the needle bar bracket support shaft !1.
Remove the wick !2.
Remove the needle bar bracket assembly !3 from the arm.
Remove the slide block !5 of the needle bar clamp !4 from the thread take-up lever set !6.
Remove the slide block !7 of the needle bar bracket assembly !3 from the zigzag lever shaft !8.
Remove the bolt !9, and then remove the needle bar guide @0 from the needle bar bracket assembly !3.
Loosen the screw @3 of the needle bar clamp !4, and then remove the needle bar @1.
LH4-B800E
2 - 17
2. DISASSEMBLY
u
q
e
o
i
w
y
r
t
!1
y
!0
Remove the set screw q, and then remove the support shaft w.
Remove the wick e.
Loosen the two set screws r.
Remove the thread take-up lever set u and the washer i from the thread take-up crank o.
Remove the needle bar bracket slide block t.
Remove the two bolts !0 and the screw !1, and then remove the crank rod guide y.
2 - 18
LH4-B800E
2. DISASSEMBLY
2-11. Presser bar mechanism
!4
w
!5
!6
q
!1
e
u
!2
!3
o
r
!0
!7
t
!0
!7
!8
i
@1 !9
@0
y
@6
u
@5
u
@4
!2
Loosen the presser adjusting nut q.
Remove the presser adjusting screw w, and then remove the spring guide e, compression spring r and plain
washer t.
Remove the shoulder screw y, and then remove the presser bar guide bracket assembly u from the knee lifter lever
i.
Remove the screw o, and then remove the presser roller bracket !0 from the presser bar !1.
Loosen the set screw !2.
Remove the presser bar !1, and then remove the oil rejector !3 and the presser bar guide bracket assembly u.
Remove the rubber cap !4.
Remove the screw !5, and then remove the needle bar guide !6.
Loosen the set screw !7, and then remove the roller shaft !8 from the presser roller bracket !0.
Remove the plain washer !9 and the retaining ring @0, and then remove the roller @1 from the roller shaft !8.
Remove the shoulder screw @5, and then remove the presser bar lifter link @6 from the presser bar guide bracket @4.
LH4-B800E
2 - 19
2. DISASSEMBLY
2-12. Upper thread trimmer mechanism
q
e
w
r
t
Remove the screw q, spring washer w and plain washer e, and then remove the upper thread trimmer assembly r
from the upper thread trimmer lever t.
2 - 20
LH4-B800E
2. DISASSEMBLY
q
$3
!6
w
$5
$4
@9
!9
!6
!7
e
@0
t
r
!8
#0 #1
@5
@8
@7
#5
w
@4
w
#3
$1$2#9
$0
#2
#6
#8
#4
#7
@4
e
!0
!1
!5
!2
i
u
y
o
!4
!3
u
y
Remove the two springs q from the upper thread trimmer lever set w.
Remove the eye bolt e, and then remove the trimmer driving arm assembly r from the trimmer driving lever t.
Remove the eye bolt y and the plain washer u, and then remove the support plate i and the stopper o from the
trimmer driving arm !0.
Remove the retaining ring !1, and then remove the driving arm roller !2.
Remove the nut !3 and the spring washer !4, and then remove the roller shaft !5 from the support plate i.
Remove the eye bolt !6, and then remove the longitudinal feed arm assembly !7 from the trimmer driving lever !8.
Remove the two retaining rings !9, and then remove the longitudinal feed arm roller @0.
Remove the washer @7 and the two shoulder screws @8, and then remove the upper thread trimmer lever set w from
the upper thread trimmer fulcrum shaft @9.
Remove the roller @5.
Remove the screw #0 and the plain washer #1, and then remove the setting plate #2 from the upper thread trimmer
lever assembly #3.
Remove the nut #4 and the plain washer #5, and then remove the support shaft @4 from the setting plate #2.
Remove the two collars #6 and the two screws #7, and then remove the back plate #8 and the stop plate #9 from the
upper thread trimmer lever assembly #3.
Remove the spring $0.
Remove the screw $1, and then remove the spring hook plate $2 from the upper thread trimmer lever assembly #3.
Remove the rubber cap $3.
Loosen the set screw $5 of the set screw collar assembly $4, and then remove the upper thread trimmer fulcrum shaft
@9.
LH4-B800E
2 - 21
2. DISASSEMBLY
2-13. Thread breakage detection mechanism
q
u
w
r
!0
!0
e
!1
u
o
!2
t y
!3
!4
!5
i
o
u
Remove the screw q, and then remove the lever stopper w.
Remove the screw e, and then remove the lever stopper r.
Remove the screw t, and then remove the balancer y from the cutter bar fixing plate u.
Loosen the set screw i, and then remove the cutter bar fixing plate u from the thread breakage perceiving shaft o.
Remove the two screws !0, and then remove the thread breakage sensor assembly.
Take the thread breakage perceiving shaft o out from the arm.
Remove the plain washer !2, plain washer !3 and screw !4, and then remove the thread guide !5 from the thread
breakage perceiving shaft o.
2 - 22
LH4-B800E
2. DISASSEMBLY
2-14. Lubrication mechanism
Shaft bush mechanism
w
e
u
y
q
i
r
e
t
r
w
Remove the screw q, and then remove tube support U w.
Remove the wicks e and r, and then disconnect the oil tube t.
Remove the felt y, and then remove the wick u from bush F i.
LH4-B800E
2 - 23
2. DISASSEMBLY
Needle zigzag mechanism
w
t
q
r
q
w
e
r
t
Remove the screw q, and then remove the felt support w from the motor bracket e.
Remove the screw r, and then remove the tube support t.
2 - 24
LH4-B800E
2. DISASSEMBLY
Oil tubes
q
u
y
r
t
!2
e
w
!3
!1
u
r
!4
q
t
!1
!4 !3
!2
o!0
u
u
o
!0
i
y
i
!1
i
o!0
!1
u
Remove the fastening band q.
Remove the screw w, and then remove tube support M e.
Disconnect the oil tube r that is connected to the oil terminal and the plunger pump.
Remove the screw t, and then remove the tube support y.
Remove the cord holder i, screw o and washer !0, and then disconnect the oil tubes !1 and u that are connected
between the oil terminal and the oil outlet.
Remove the screw !2, and then remove the felt holder !3.
Remove the felt !4, and then disconnect the oil tube u.
LH4-B800E
2 - 25
2. DISASSEMBLY
Oil terminal mechanism
w
q
i
!7
!8
!5
@5
!6
e i
o
!5
e
!9
r
@0
!4
@4
@1
@3
!5
@2
!5
i
!7
!6
Remove the screw q, and then remove the cap w and the felt @5.
Remove the screw o, and then remove felt base A r from the wick base support i.
Remove the screw e, and then remove the wick base support i.
Remove the two screws !4, and then remove the oil terminal !5 from the wick base support i.
Remove the oil tube !6 that is connected between the oil terminal and the oil outlet from the tube support !7.
Remove the screw !8, and then remove the tube support !7 from the wick base support i.
Remove the oil tube !6 that is connected between the oil terminal and the oil outlet from the wick base support i.
Disconnect the oil tube !9 that is connected between the oil terminal and the oil outlet from the oil terminal !5.
Disconnect oil pipe B @0 from the oil terminal !5.
Remove the oil cap @1, and then remove the packing @2 from the oil terminal !5.
Remove the collar @3 and the wick @4 from the oil terminal !5.
2 - 26
LH4-B800E
2. DISASSEMBLY
Plunger pump mechanism
!3
!7
io
u
!2
!1
!0
!6 !5
!7
e
e
!4
!9
q
y
r
t
uio
w
q
r
t
io
u
!4
!4
@1
@2
@0
Remove the three screws q, and then remove the oil filter bracket w from the bed.
Remove the oil tube e that is connected between the plunger and the filter from the oil filter bracket w.
Remove the two springs r and the two screws t, and then remove the pump filter y from the oil filter bracket w.
Remove the cord holder u, screw i and plain washer o.
Remove the screw !0, and then remove tube support D !1 from the oil tube !2 that is connected between the oil
terminal and the oil outlet and from the bed.
Remove the oil tube !3 that is connected between the oil teminal and the plunger pump from the lubricating holeto the
left of bush M !4.
Remove the screw !5, and then remove the tube support !6 from the oil tube !7 and from the bed.
Remove the outlet oil tube !7 from the lubricating hole to the right of bush M !4.
Remove the oil tube e that is connected between the plunger and the filter from the inlet hole to the left of bush M !4.
Remove the oil tube !9 from the inlet hole to the right of bush M !4.
Remove the two screws @0, and then remove the two plungers @1 and the two compression springs @2 from bush M !4.
LH4-B800E
2 - 27
2. DISASSEMBLY
Rotary hook lubricating mechanism
y
o
i
eqw
!0
y
r
u
o
t
u
!1
!0
Remove the spring q and the screw w, and then remove the rubber presser e from the bed.
Remove the wick r from the felt support t.
Remove the wick y from the felt support t.
Remove the two screws u, and then remove the felt support t from the bed.
Remove the end of the felt i from the bush o.
Remove the spring !0 from the bush o.
Remove the collar !1 from the bush o.
Remove the wick y from the collar !1.
2 - 28
y
LH4-B800E
2. DISASSEMBLY
2-15. Rotary hook mechanism
r
y
e
w
q
e
t
Remove the two screws q, and then remove the rotary hook holder w.
Loosen the set screw e, and then remove the rotary hook r.
Loosen the set screw t, and then remove the rotary hook joint assembly y.
LH4-B800E
2 - 29
2. DISASSEMBLY
2 - 30
LH4-B800E
3. ASSEMBLY
3. ASSEMBLY
3-1. Lower shaft and idle pulley mechanism
w
q
e
Insert e
r
y
i
t
u
o
!1
!0
Align edges of pulley
and lower shaft
0.5 mm
After attaching the timing belt to the idle pulley assembly q, insert the collar w. Insert the shaft e, and then install the
assembly to the bed with the two set screws r.
Install the timing pulley assembly t to the lower shaft y with the set screw u, and then place the set screw collar
assembly i onto the lower shaft y and then install the lower shaft y to the bed. After checking the thrust direction,
securely tighten the set screw o. The screw stop position is the start of the rotation direction.
Install the cover !0 with the two screws !1.
LH4-B800E
3-1
3. ASSEMBLY
3-2. Lower thread trimmer mechanism
Apply grease to cam groove
o and to !4
w
tr
!6
q
o
!5
!7 !4
!5
!6
r
e
i
!4
@1
@0
!9
!8
u
!1
!7
Apply grease to !9
w
o
y
@2
!0
@3
Apply grease to @3
@2 @4 y
!1
@6
!2
Apply grease to !2
!3
@5
@7
Insert the roller shaft q into the lower thread trimmer cam lever w, and secure it by tightening the nut e. Place the roller r onto
the roller shaft q, and then install the retaining ring t.
Install the lower thread trimmer cam connecting rod y to the lower thread trimmer cam o with the driving lever roller u and the
shoulder screw i. (Lower thread trimmer cam assembly !1)
Install the cover !0 to the bed.
Pass the lower thread trimmer cam assembly !1 through the cover !0 and install it to the bed with the two lever shafts !2. Tighten
the two set screws !3 so that the lower thread trimmer cam assembly !1 moves smoothly without any play.
Insert the roller r into the lower thread trimmer cam o, and then install it to the bed with the lower thread trimming cam shaft !4,
washer !5 and retaining ring !6. Secure by tightening the set screw !7.
Connect the presser lifter connecting rod set !8 and the lower thread trimmer cam lever w using plain washer D @0, and the bolt
@1.
Install the lower thread trimmer link assembly @2 with the shoulder screw @3.
Connect the lower thread trimmer link assembly @2 and the lower thread trimmer cam connecting rod y with the shoulder screw
@4.
Install the opening plate assembly @5 with the shoulder screw @6. Install the plate spring @7 as shown in the illustration.
3-2
LH4-B800E
3. ASSEMBLY
Press down
w
Forward
Back
@6
!7
q
!8
!3
!6
!5
!4
e
t
u
y
!2
i
!0
!1
r
!9
@5
@2
w
Apply grease to cam groove i
Apply grease to !0
i
o
@0
@8
@7
@1
@4
@3
#1
#2
@2
w
#3
#0
#4
@9
#3
Install the screw q to the base plate w. Install the lever assembly e and the lower thread retainer r to the base plate
w with the collar t and the screw y. Install the lower thread retainer r to the lever assembly e with the two screws
u.
Insert the roller of the lever assembly e into the cam groove of the knife driving lever i.
Install the knife driving lever i to the base plate w with the shoulder screw o, collar !0, washer U !1 and washer D
!2.
Install the lower thread clamp plate assembly !3 to the base plate w with the shoulder screw !4, plain washer !5 and
curved washer !6. Install the lower thread presser !7 to the base plate w with the shoulder screw !8 and the screw !9.
Install the fixed knife set @0 to the knife driving lever i with the two screws @1.
Install the needle plate @2 with the pan screw @3 so that it is parallel to the base plate w.
Provisionally install the base plate w to the top of the bed with the four screws @4.
While pushing the base plate w to the right so that the needle @5 is in the center of the needle hole @6 in the longitudinal direction, securely tighten the screws @4.
Connect the lower thread trimmer link assembly @7 and the knife driving lever i with the shoulder screw 4.37 @8.
Install the length feed plate @9 to the feed arm support #0 with the bolt #1 and washer #2.
Install the feed presser plate #3 with the screw #4 so that the feed mechanism moves easily when it is moved back and
forth by hand.
LH4-B800E
3-3
3. ASSEMBLY
3-3. Feed mechanism
we
!8
q
0.5 mm
@8
!7
!9
y
@1
@0
r
o
@7
!3
@4
t
@9 #0
100 N
!1
!0
!0
t
u
@2
@3
#4
#5
#3 #2
i
#1
@5 !3
#6
@6
@7
!2
#1
#8#9
t
!9
!5
Align the pulley
support shaft !3
with
the
worked surface of the bed
!6
!4
#7
#7
#8
#9
Install the two feed shaft linear bushes q to the bed. Secure the ball bearing stopper w with the screw e. Place the linear bush r onto the feed
arm support t and install it with the two retaining rings y.
Pass the feed arm support t through feed guide shaft A u and install it to the bed. Provisionally tighten the two bolts i. Place feed guide shaft
B o through the feed arm support t, align the reference lines !0, and then secure by tightening the set screw !1. Securely tighten the two bolts
i so that the feed arm support t moves smoothly.
Install the two ball bearings (688ZZNR) !2 to the bed.
Place the timing belt !3 onto the pulley B assembly !4, and then insert the support shaft !5. Install the pulley B assembly !4 to the support shaft
!5 and secure by tightening the set screw !6.
Install the motor mounting bracket !7 to the feed pulse motor !9 with the four bolts !8.
Install the pulley A assembly @0 so that there is a gap of 0.5 mm between it and the motor, and secure it by tightening the two set screws @1.
Place the timing belt !3 onto the feed pulse motor !9, and then provisionally tighten it with the three screws @2 and the three washers @3. Push the
motor mounting bracket !7 in the direction of the arrow with a force of 100 N, and then securely tighten the screws @2. Gently tighten the eye bolt
@4. If there is no tension gauge available, apply a force of 5 N at the middle of the timing belt !3 span and adjust so that the amount of deflection
at this time is 3.5 mm.
Place the belt holder @5 onto the timing belt !3, and then install it to the feed arm support t with the two bolts @6.
Install the DC fan motor 40 assembly @7 to the feed motor cover @9 with the two screws @8. Install the feed motor cover @9 to the bed with the
screw #0.
Install the feed home position sensor #1 to the feed sensor support plate #2 with the screw #3. Install the feed sensor support plate #2 to the bed
with the screw #4 and the plain washer #5.
Pass the cords for the feed pulse motor !9, DC fan motor 40 assembly @7 and feed home position sensor #1 through the cord holder #6 and the
cord supports #7 as shown in the illustration, and secure to the bed with the screw #8 and the plain washer #9.
3-4
LH4-B800E
3. ASSEMBLY
q
e
w
r
[For long-hole]
y
u
y
u
[-2 specifications]
t
t
u
u
!0
o
i
For long-hole (-5) specifications
Insert the linear bush 9.53 (for long-hole) q into the feed arm support -5 (for long-hole) w.
Secure the linear bush 9.53 (for long-hole) q by tightening the linear bush stopper plate (for long-hole) e and the
screw 4.37-40x6 r.
Replace the two ball bearing stoppers t with the two ball bearing stoppers (for long-hole) y, and change the two
linear bushes u to the positions for long-hole specifications.
With feed guide shaft A-5 (for long-hole) i inserted into the feed arm support -5 (for long-hole) o, insert into the bed.
Insert feed guide shaft B-5 (for long-hole) !0 into the feed arm support -5 (for long-hole) o. Install so that the reference
line on feed guide shaft B-5 (for long-hole) !0 is aligned with the edge of the feed arm support -5 (for long-hole) o.
Install feed guide shaft A-5 (for long-hole) i to the bed so that the feed arm support -5 (for long-hole) o moves
smoothly.
LH4-B800E
3-5
3. ASSEMBLY
w
e
y
t
@4
i
o
@2
u
q
t
@1
@0
r
!5
!6
@3
!9
!6
!0
!2
!1
!3
!2
!4
!6
!7
r
!8
Provisionally install the length feed plate q to the feed arm support r with the two eye bolts w and the two spring
washers e. Provisionally install the two feed presser plates t to the bed with the four screws y. Then tighten the
screws y to secure the feed presser plates t so that the window in the length feed plate q is in the center of the
needle plate when the feed arm is moved forward and back. Securely install the length feed plate q with the eye bolts
w so that the feed arm moves smoothly. Install the feed cover u to the feed arm support r with the eye bolt i and
the plain washer o.
Install the cam !0 to the support plate !3 with the two eye bolts 4.37x5 !1 and the two plain washers !2. Install the
support plate !3 to the feed arm !5 with the two eye bolts !4 and the two plain washers !2. (Feed arm assembly !6)
Install the feed arm assembly !6 to the feed arm support r with the feed arm support shaft !7. Secure the feed arm
support shaft !7 by tightening the set screw !8.
Insert the spring @0 into the work clamp !9, and then install the work clamp !9 to the feed arm assembly !6 with the
shoulder screw @1. Install the feed arm support @2 and the opening cam assembly @3 to the feed arm assembly !6 with
the two screws @4.
3-6
LH4-B800E
3. ASSEMBLY
3-4. Bobbin presser mechanism
r
q
w
y
t
e
11.7 mm
u
t
i
o
Approx. 12.5 mm
!0
t
!2
!1
!3
!4
Install spring hook U q to the bobbin presser bracket w. Install the screw e and the nut r to the bobbin presser
bracket w. At this time, install the screw so that the length shown in the illustration is 11.7 mm. Install the bobbin
presser t to the bobbin presser bracket w with the set screw y. At this time, install so that the end of the bobbin
presser t is at the center of the bobbin case u.
Install the auxiliary plate i and the opening plate o with the shoulder screw !0.
Install the bobbin presser bracket w and the auxiliary plate i to the bed with the shoulder screw !1. Install the
opening plate o to the rotary hook cover !3 with the shoulder screw !2. Attach the two extension springs !4.
Turn on the power. After the mechanism moves to the home position, turn the screw e and the nut r to adjust so that
the clearance between the bobbin presser t and the edge of the bed is approximately 12.5 mm.
LH4-B800E
3-7
3. ASSEMBLY
3-5. Tension release mechanism
w
!1
Gauge
e
u
q
17.5
i
o
1.8
y
u
t
!0
y
19.2
0.2 mm
o
e
(A)
(B)
Apply grease to !2
!2
27
!7
!1
!6
4 3
1
0
2
0.5 - 1 mm
!8
!3
!5
!4
Apply grease to !5
(Figure C)
!1
Install the tension release solenoid q to the solenoid holder e with the two screws w.
Pass the tension release solenoid link t through the plate y. Install the tension release solenoid link t to the plunger u that was
removed from the tension release solenoid q using the plunger pin i.
Install the spring o to the plunger u. Insert the plunger u into the tension release solenoid q, and then install the plate y to the
solenoid holder e with the bolt !0 so that dimension (A) is 13.7 mm.
Install the tension release link !1 with the shoulder screw !2 from the face plate side.
Provisionally install the tension release solenoid assembly !3 with the two screws !4. Connect the tension release solenoid
assembly !3 and the tension release link !1 with the shoulder screw !5.
Adjust the position of the tension release solenoid assembly !3 so that the tension release link !1 protrudes from the edge of the
tension stud bracket assembly !6 on the arm by 19.2 ± 0.2 mm. Then securely tighten the screw !4.
Insert the tension release pin !7 into the tension stud bracket assembly !6, and then insert it into the arm. Tighten the screw !8 so
that the tension discs are open by 0.5 to 1 mm when the tension release link !1 is pushed in the direction of the arrow (B).
If not using a gauge, insert the tension release pin !7 into the tension stud bracket assembly !6, insert it into the arm, and then
tighten the screw !8 at almost the center of the screw stop on the tension stud bracket assembly !6.
With the tension release link !1 pushed in the direction of the arrow (B) (Figure C), move the tension release solenoid assembly !3
so that the tension discs are open by 0.5 to 1 mm, and then tighten the screw !4.
3-8
LH4-B800E
3. ASSEMBLY
q
t
u
y
i
@3
@4
@4
r
e
w
0.3 - 0.5 mm
0.1 - 0.3 mm
@2
!2
!3
!1
!0
i
o
#4
#3
@1
#7
#5
!8
4 3
!7
#6
0
!9
@8
@5
@6
@7 @9
0
#1
4 3
#0
1
!6
1
!5
2
!4
2
@0
#2
Connect the adjusting lever q, lever link w and tension take-up lever e with the two shoulder screws r. Install the
lever t to the adjusting lever q with the screw y and the washer u. (Tension lever take-up assembly i)
Insert the washer o into the bottom of the tension lever take-up assembly i, and then install the tension lever takeup assembly i to the arm with the shoulder screw !0. Install the tension lever take-up assembly i to the tension
release shaft !3 with the screw !1 and the washer !2.
Place the two tension discs !4, tension disc presser !5, tension disc presser !6, tension adjusting spring !7, washer !8
and tension nut !9 onto the sub tension stud @0. (Sub thread tension assembly @1)
Insert the tension release pin @2 into the sub thread tension assembly @1, and then install the sub thread tension
assembly @1 to the arm.
To adjust the thread tension, turn on the power. After the mechanism moves to the home position, press the RESET
key to lower the presser foot.
Loosen the screw @3, and then adjust the thread tension by adjusting the clearances between the tension release cam
@4 and the tension release pin @2 as shown in the illustration.
Press the RESET key to raise the presser foot, and then check that the opening clearance between the tension discs
is 0.5 to 1 mm. Then, press the RESET key again to lower the presser foot, and check that the tension discs are firmly
closed.
Place the tension discs @5, tension disc presser @6 and tension disc presser @7 onto the tension stud @8. Place the
collar @9 onto the tension stud @8 as far in as it will go. Place the tension spring #0 and the washer #1 onto the tension
stud @8. Then tighten the tension nut #2. (Tension stud assembly #3)
Insert the tension release pin @2 into the tension stud assembly #3. Provisionally install the tension release lever
bracket #4 to the tension stud assembly #3. Then attach the spring #5. Install the tension release lever #6 with the
shoulder screw #7 so that the spring #5 is straight. Then fully tighten the tension stud assembly #3.
LH4-B800E
3-9
3. ASSEMBLY
3-6. Presser lifter mechanism
Apply grease to o
!0
o
u
i
@2 @3
@4 @3
Apply grease
Apply grease to @3
!6
u
!7 !5
!1
!1
Insert into the
cam groove
(B)
!4
t
r
y
!3
Apply grease to !8
(A)
!9
@1
@0
Apply grease to r
e
q
!8
!2
@6
y
@5
w
Apply grease to @5
y
Install the presser lifter connecting rod assembly q and the knee lifter lever w with the spacer e, plain washer D r
and bolt t. (Presser lifter connecting rod set y)
Install the presser lifter connecting rod set y and the lifter shaft assembly u with the shoulder screw i.
Insert the two trimmer driving levers o to the inside of the arm. Pass the two O-rings !0 into the shaft from the outside
of the arm, and fit them into the hollow in the arm.
Insert the pin of the tension release driving lever !1 into the cam grove in the lifter shaft assembly u, and then insert
into the arm.
Install the O-ring !3 to the tension release shaft !2, and then insert into the arm. At this time, insert the tension release
cam !4, pass the tension release driving lever !1 through the tension release cam !4, and then install the retaining ring
!5.
While pushing the tension release shaft !2 in the direction of the arrow (A), push the tension release driving lever !1
in the direction of the arrow (B) to align it with the screw stop on the tension release shaft !2, and secure by tightening
the set screw !6. Then secure the tension release cam !4 by tightening the set screw !7.
Install the lifter shaft !8, small plain washer 8 !9 and retaining ring E6 @0 to the arm. Secure by tightening the set screw
@1.
Install the driving lever roller @2 to the trimmer driving lever o with the shoulder screw @3. Install the ball bearing @4 to
the trimmer driving lever o with the shoulder screw @3.
Install the presser lifter connecting rod set y to the arm with lifter shaft A @5 and the set screw @6.
3 - 10
LH4-B800E
3. ASSEMBLY
u
q
o
i
r
i
q
w
e
19.6 0.3
r
t
y
1 0.3
Install the motor lever w to the pulse motor N assembly (for needle zigzag) q with the set screw e so that the
dimensions are as shown in the illustration.
Install the gear 15.75 t to the pulse motor FT assembly (for presser lifter) r with the set screw y so that the
dimensions are as shown in the illustration.
Install the pulse motor N assembly (for needle zigzag) q and the pulse motor FT assembly (for presser lifter) r to the
motor bracket u with the bolts i so that the directions of the cords are as shown in the illustration. (Motor bracket
assembly o)
LH4-B800E
3 - 11
3. ASSEMBLY
!0
!7
!1
!6
@0
!8
!3
!2
!9
@1
Apply grease to !9
@2
o
@3
o
!5
Apply grease
@5
!1
!4
@4
@6
!3
@7
!1
@6
@7
!7
@8
!6
@9
#0
Insert the two linear ball bearings !0 into the guide bracket !1.
Provisionally install the bearing holder !2 with the bolt !3.
Pass the two guide shafts !4 though the motor bracket assembly o and the guide bracket !1. Secure the guide shafts !4 by tightening the four
set screws !5.
Provisionally install the presser driving arm !6 to the guide bracket !1 with the four bolts !7. Then securely tighten the bolt !3.
Insert the washer !8 into the driving arm presser !9, and then pass it through the presser driving arm !6 and insert into the motor bracket assembly
o.
Provisionally tighten the set screw @0. Then tighten the bolt !7 and the set screw @0 so that the presser driving arm !6 moves up and down easily
and so that there is no play in the gear.
Insert the motor bracket assembly o into the arm from the top. Position it using the two positioning pins @1, and then install it by tightening the four
screws @2 and the screw @3.
Install the clamp sensor plate @4 with the pan screw @5.
Install the sensor @6 with the screw @7.
Install the clamp sensor dog @8 to the upper thread trimmer driving link #0 with the two screws @9.
3 - 12
LH4-B800E
3. ASSEMBLY
3-7. Needle zigzag mechanism
!5
e
r
!4
w
q
o
y
!3
t
@0
u
i
65 mm
Knot
!8
!7
12 mm
!6
e
!9
@2
@1
!5
!2
w
!1
!0
Pass the zigzag connecting rod shaft q through the zigzag lever w and zigzag connecting rod e, and then secure it
by tightening the set screw r.
Pass the wick t through the zigzag connecting rod shaft q and the oil tube y, and then push it into the lubricating
hole u. Push the felt i into the lubricating hole u to prevent the oil tube y from coming out. Install the two fastening
bands o so that they face in the position shown in the illustration.
Pass zigzag lever assembly F !0 through the arm, and position it in the thrust direction using the thrust washer !1 and
the zigzag lever w. Then secure zigzag lever assembly F !0 by tightening the bolt !2.
Install the sensor !3 to the zigzag sensor plate !5 with the screw !4.
Insert the wick !6 into the motor lever shaft !7. Place the washers !8 onto the motor lever shaft !7. Pass the motor
lever shaft !7 through the zigzag connecting rod e and the washers !8 so that the screw stop is aligned correctly, and
then secure to the motor lever @0 by tightening the set screw !9.
Install the zigzag sensor plate !5 to the motor bracket @2 with the screw @1 so that the screw @1 is in the middle of the
slot.
LH4-B800E
3 - 13
3. ASSEMBLY
3-8. Cutter mechanism
!0
o
e
r
tr
u
@5
w
q
@3
@4
i
y
!5 !6 !7
!7
!4
!1
!3
@6
@1
!2
29.8
Align edges
!4
!1
!5
0
-0.5
!9
!7
!6
@0 @1
!1
!9
@2
@8
@7
@7
!8
@7
Insert
Pass the cutter driving arm shaft q through the set screw collar w and the cutter driving arm assembly e in the direction shown
in the illustration. Secure the set screw collar w with the two set screws r so that the screw stops are aligned correctly. Install the
cutter driving arm assembly e with the set screw t so that there is no play in the thrust direction and so that there is no gap. Install
the cutter bar guide o with the four screws !0. Install the cutter driving link y and the needle bar bracket slide block u to the
driving shaft holder assembly i. Install the other cutter driving link y to the cutter driving arm assembly e.
Install the stopper cushion !4 to the cutter solenoid !1. Install the solenoid stopper !5 to the solenoid plunger with the spring
washer !6 and two nuts !7 as shown in the illustration. Install the cutter solenoid !1 to the cutter solenoid bracket !3 with the three
bolts !2. At this time, install so that the oil tube @7 passes underneath the cutter solenoid bracket !3.
Connect the cutter driving link !8 and the cutter link bracket !9 with the shoulder screw @0. Provisionally install the bolt @1. (Cutter
link bracket assembly @2)
Install the cutter link bracket assembly @2 to the cutter link shaft @5 with the washer @3 and retaining ring E6 @4.
Insert the solenoid plunger into the cutter link bracket !9. Then tighten the bolt @1 so that the end of the solenoid plunger is aligned
with the edge of the cutter link bracket !9.
Install the cutter solenoid bracket !3 to the arm with the four screws @6.
Check that the plunger of the cutter solenoid !1 moves easily.
Insert the oil tube @7 and the cord of the cutter solenoid !1 in between tube support U @8 and the arm.
3 - 14
LH4-B800E
3. ASSEMBLY
w
!3
!4
!1
!7
@0
!6
t
r
r
q
q
e
!9
q
@1
@2
(A)
y
@3
@4
4.5 mm
!4
e
i
@9
!2
u
!5
1.5 mm
u
Align edges
@3
@3
@5
@5
o
!0
o
!0
!8
!7
5 mm
q
Place against end of shaft
q
Insert the cutter driving shaft q into the arm from the top, and then pass it through the holes in the felt w and the
driving shaft holder assembly e. Pass the cutter driving shaft q through the oil rejector r. Provisionally secure the
driving shaft holder assembly e with the two set screws t.
Fully tighten the set crews t so that the edges of the cutter driving shaft q and the bush i are aligned when the
clearance between the edges of the cutter link bracket y and the cutter solenoid u is 1.5 mm (or when dimension (A)
is 15.5 mm).
Install the screw assembly o to the arm, and secure it with the nut !0 so that the stepped section of the cutter driving
shaft q protrudes by 5 mm from the processed surface of the arm jaw.
Attach the spring !1 to the cutter driving arm assembly !2 and the tension release shaft !3.
Install the knife sensor assembly !4 with the screw !6 so that the clearance between the knife sensor assembly !4 and
the solenoid stopper !5 is 4.5 mm. At this time, be careful not to clamp the wick @9.
Install the cutter holder !7 to the cutter driving shaft q with the bolt !8.
Provisionally install cutter holder M !9 to the cutter holder !7 with the bolt @0. Provisionally install cutter holder DL @1
to cutter holder M !9 with the screw @2. Install the cutter @3 to cutter holder DL @1 with the screw @4. Fully tighten the
bolts !8 and @0 so that the cutter @3 is in the center of the cutter groove in the needle plate @5 when the cutter is
lowered.
LH4-B800E
3 - 15
3. ASSEMBLY
@6
@2
@3
0.3 mm
@4
@7
Lowest position
Top of needle plate
@8
Lowest position
Top of needle plate
1.5 - 2 mm
Tighten the screw @2 so that the distance between the needle bar @6 and the cutter @3 is 0.3 mm.
Tighten the screw @4 so that the top of the cutter blade and the top of the needle plate are aligned when the cutter @3
is pushed down manually to its lowest position.
For a flat cutter @8, tighten the screw @4 so that it is 1.5 to 2 mm from the top of the needle plate.
3 - 16
LH4-B800E
3. ASSEMBLY
3-9. Upper shaft and tension pulley mechanism
Upper shaft pulley
mating mark
qe
y
!5
100 N
r
w
!6
!8
(A)
@1
!9
!0
i !4u
y
t
o
q
@0
r
!4
!0
r
!2
!1
@2 (Screw stop side)
@2
!3
!5
!9
@1
!6 !7
0.5 mm
Install the two retaining rings q to the upper shaft w. Press-fit the ball bearing e as far as the retaining rings q.
(Upper shaft assembly r)
Place the timing pulley U assembly t, timing belt y, bobbin winder pulley u and set screw collar assembly i onto
the upper shaft assembly r. While pushing the timing pulley U assembly t against the retaining rings q, secure it by
tightening the set screw o. While pushing the bobbin winder pulley u against the timing pulley U assembly t, secure
it by tightening the two set screws !0.
Install the thread take-up crank !1 to the upper shaft assembly r with the screw !2 and the set screw !3.
Secure the set screw collar assembly i to the upper shaft assembly r using the thread take-up crank !1 and the two
set screws !4 so that there is no play.
Provisionally install the tension pulley assembly !5 with the two bolts !6 and the two plain washers !7. Set the phase
between the upper shaft and the lower shaft so that the mating mark (A) on the lower shaft timing pulley !8 is facing
straight down when the upper shaft assembly r is at the needle up stop position. While pushing the tension pulley
assembly !5 with a force of 100 N, secure it by tightening the two bolts !6.
Install the synchronizer assembly H80 !9 to the arm with the screw @0.
Install the pulley assembly @1 with the screw @2 so that the screw stop is at the front, and so that the clearance
between it and the synchronizer assembly H80 !9 is 0.5 mm.
LH4-B800E
3 - 17
3. ASSEMBLY
3-10. Needle bar and thread take-up mechanism
q
e
w
t
!1
u
y
o
!0
(Screw stop side)
q
i
r
Install the crank rod guide q with the two bolts w and the screw e.
Install the needle bar bracket slide block r to the thread take-up lever set t. Pass the wick o through the support
shaft hole in the arm. Insert the washer y into the thread take-up lever set t, and then install it to the thread take-up
crank u. Insert the needle bar bracket slide block r into the groove in the crank rod guide q. Secure the thread takeup lever set t by tightening the two set screws i.
Insert the support shaft !0 and secure it by tightening the set screw !1 so that the thread take-up moves smoothly with
no play.
3 - 18
LH4-B800E
3. ASSEMBLY
!1
@1
!0
t r
q
q
e
!3
Place onto projection
of needle bar clamp
set
!2
o
w
@0
i
u
y
q
r
!5 !6
e
!9
!4
!8
!7
Insert the needle bar w into the needle bar bracket assembly q, and then pass it through the needle bar clamp e as shown in the illustration.
Set the projection of the needle bar clamp e into the groove in the needle bar guide r, and then install to the needle bar bracket assembly q with the bolt t so that
the needle bar w moves smoothly.
Insert the slide block y of the needle bar bracket assembly q into the zigzag lever shaft u, and insert the slide block i of the needle bar clamp e into the thread
take-up lever set o.
Insert the needle bar bracket assembly q into the arm, and then install it while inserting each of the slide blocks.
Pass the wick @1 of the needle bar bracket support shaft !0 through the arm.
Insert the needle bar bracket support shaft !0, and then secure it by tightening the set screw !1 so that there is no play in the needle bar bracket assembly q.
Insert the needle bar bracket guide !2 into the arm, and then secure it by tightening the set screw !3 so that there is no play in the needle bar bracket assembly q.
Install the set screw !5 and nut !6 to the stopper !4, and then install it to the arm with the screw !7.
Install the set screw !8 and nut !9 to the arm.
When the needle bar w is at its maximum zigzag position, tighten the set screws !5 and !8 against the needle bar bracket assembly q, and then loosen them again
by about 1/4 of a turn each. Then tighten the nuts !6 and !9.
Insert the needle bar thread guide @0 into the needle bar w.
LH4-B800E
3 - 19
3. ASSEMBLY
3-11. Presser bar mechanism
@0
q
!6
t
e
w
!7
t
r
!0
!5
!4
o
i
Install with !9 at the top
!8
!9
@1
u
t
r
!8
@5
@4
y
10 mm
@3
@3
u
10 mm
@2
!4
Apply grease to !3
!5
t
#0
!3
Align edges
@9
!0
!1 !2
@9
30 mm
@6
@7
Top
@8
!7 !6
Bottom
Install the presser bar lifter link q to the presser bar guide bracket e with the shoulder screw w. Install the set screw r to the presser bar guide
bracket e. (Presser bar guide bracket assembly t)
Install the upper thread trimmer driving link y and the knee lifter lever u with the shoulder screw i. (Lifter shaft assembly o)
Install the roller !0 to the roller shaft !3 with the plain washer !1 and the retaining ring !2. Install the roller shaft !3 to the presser roller bracket !4.
Secure the roller shaft !3 by tightening the set screw !5.
Provisionally install the needle bar guide !6 to the arm with the screw !7 as shown in the illustration.
Insert the presser bar !8 into the arm, and then pass it through the oil rejector !9 and the presser bar guide bracket assembly t.
Position the needle bar guide !6 so that the presser bar !8 moves smoothly, and then secure it by tightening the screw !7. Tap in the rubber cap
@0. Install the presser roller bracket !4 to the presser bar !8 with the screw @1.
Connect the presser bar guide bracket assembly t and the knee lifter lever u with the shoulder screw @2.
Place a 10 mm gauge @4 underneath the work clamp @3.
Turn on the power. After the mechanism moves to the home position, check that the setting for memory switch No. 05 (presser foot height at neutral
position) is 10 mm. (If it is not set to 10 mm, set it to 10 mm.)
While pushing the presser bar !8 down from above, tighten the set screw r so that the roller !0 is not at an angle to the V-shaped groove in the
presser arm @5. Then remove the gauge @4 and turn off the power.
Insert the spring guide @6, compression spring @7 and plain washer @8, and with the presser adjusting screw @9 at a height of 30 mm, tighten the
presser adjusting nut #0.
3 - 20
LH4-B800E
3. ASSEMBLY
3-12. Upper thread trimmer mechanism
e
@4
@5
w
q
Apply grease to q
#0
@9
#4
#3
y
tr i
u
!6!7
!5
!4
!0
o
!3
!2
Approx. 1 mm
#3
@7
#5
Apply grease to #7 and #8
@1
#9
#5
!2
@4
$1
$0
!9
@0
i
#4
#8
#6
@1
!8
#2
#5
Aligned
$5 $4
u
Align edges
@8
#6
#2
Apply grease to #0
!1
#7
i
#1
@6
$3
$2
Apply grease to @2
@3
@2
!8
#5
Insert the upper thread trimmer fulcrum shaft q into the arm. Secure the upper thread trimmer fulcrum shaft q with the set screw collar
assembly w so that it turns smoothly. Install the rubber cap e from the top of the arm.
Install the spring hook plate r to the upper thread trimmer lever assembly y with the screw t. Attach the spring u to the stop plate i as
shown in the illustration. Install the back plate o and the stop plate i to the upper thread trimmer lever assembly y with the two collars
!0 and the two screws !1. Apply grease to the sliding surfaces.
Install the support stud !2 to the setting plate !5 with the nut !3 and the plain washer !4. Install the setting plate !5 to the upper thread
trimmer lever assembly y with the screw !6 and the plain washer !7.
Press-fit the longitudinal feed arm pin !8 onto the longitudinal feed arm !9. Secure it by tightening the set screw @0. Install the bolt @1. Place
the longitudinal feed arm roller @2 onto the longitudinal feed arm pin !8 and secure it with the two retaining rings @3. (Longitudinal feed arm
assembly)
Install the eye bolt @4 to the trimmer driving arm @5. Install the roller shaft @6 to the support plate @9 with the nut @7 and the spring washer
@8. Place the driving arm roller #0 onto the roller shaft @6. Secure the driving arm roller #0 with the retaining ring #1. Install the support plate
@9 and the stopper #2 to the trimmer driving arm @5 with the eye bolts #3 and the plain washers #4. (Trimmer driving arm assembly)
Install the upper thread trimmer lever set #5 to the upper thread trimmer fulcrum shaft q with the two washers #6 and shoulder screws #7.
Place the roller #8 onto the support stud !2 of the upper thread trimmer lever set #5, and then place it into the groove in the presser roller
bracket #9.
Pass the longitudinal feed arm pin !8 of the longitudinal feed arm assembly $0 through the upper thread trimmer lever set #5, and
provisionally install it to the trimmer driving lever $1 with the eye bolt @1. Provisionally install the trimmer driving arm assembly $2 to the
trimmer driving lever $3 with the eye bolt @4.
Turn on the power. After the mechanism moves to the home position, press the RESET key to lower the presser foot.
Tighten the eye bolt @1 of the longitudinal feed arm assembly $0 so that the slot of the upper thread trimmer lever set #5 and the edge of the
washer #6 are aligned. Tighten the eye bolt @4 so that the stop plate i and the stopper #2 are in the positions shown in the illustration.
Attach the two springs $4 to the upper thread trimmer lever set #5. Attach the larger hooks of the springs $4 to the pins $5 on the arm.
LH4-B800E
3 - 21
3. ASSEMBLY
r
y
t
q
w
Install the upper thread trimmer assembly q to the upper thread trimmer lever w with the screw r, spring washer t
and plain washer y.
3 - 22
LH4-B800E
3. ASSEMBLY
3-13. Thread breakage detection mechanism
!5
!4
i
1 mm
!2
q
e
u
r
!3
t
w
u
y
o
q
i
i
!1 !0
Provisionally install the thread guide w to the thread breakage perceiving shaft q with the plain washer e, plain
washer r and screw t, and then insert the thread breakage perceiving shaft q into the arm.
Provisionally install the thread breakage sensor assembly y with the two screws u.
Secure the cutter bar fixing plate i to the thread breakage perceiving shaft q with the set screw o.
Install the balancer !0 to the cutter bar fixing plate i with the screw !1.
Install the lever stopper !2 at the correct angle with the screw !3. Provisionally install the lever stopper !4 with the
screw !5.
LH4-B800E
3 - 23
3. ASSEMBLY
3-14. Lubrication mechanism
Shaft bush mechanism
Wick should not protrude from here
q
e
Push
r
t
w
Push so wick
touches
Push so they
touch the upper
shaft
Insert the wick q into bush F w. Insert the felt e to stop the wick q from coming out.
At this time, push in firmly so that the wick r inside bush F w is touching the wick q and is also touching the upper
shaft t.
* If the wick is not pushed in firmly enough, seizure of the upper shaft may occur.
3 - 24
LH4-B800E
3. ASSEMBLY
q
w
t
w
e
q
r
e
Pass the wick q through tube support U w and push it firmly into the upper shaft lubrication hole. Pass the wick e
through tube support U w and push it firmly into the zigzag lever shaft lubrication hole.
Install tube support U w with the screw r. Pass the oil tube t around the outside of tube support U w as shown in
the illustration.
LH4-B800E
3 - 25
3. ASSEMBLY
Needle zigzag mechanism
o
t
t
!0
r
e
y
i
w
u
!2
q
t
e
!2
!1
o
r
i
y
q
w
u
Pass the oil tube q through tube support U w and the tube support e, and secure it with the screw r.
Install the felt support t to the motor bracket !0 with the screw o so that the felt y of the felt support t is gently
touching the felt i of the zigzag connecting rod u.
Pass the oil tube q around the outside of tube support U w as shown in the illustration so that it does not touch the
solenoid stopper !1, and then pass it in between the cutter solenoid !2 and the arm.
3 - 26
LH4-B800E
3. ASSEMBLY
Oil tubes
t
r
w
io
e
t
u
y
u
io
y
t
q
!6
w
!5
!0
!2
q
!3
!4
y
q e
r
t
i
o
u
t
!2
!1
y
!1
!0
!6
Insert the felt q into the arm, and then insert it into the hole in the thread take-up lever cover w.
Install the felt holder e with the screw r, and then secure the felt q and the oil tube t.
Install the oil tube y that is connected between the oil terminal and the oil outlet with the cord holder u, screw i and
washer o.
Clamp the oil tube t under the cord holder u.
Install the tube support !0 with the screw !1, and then secure the oil tube t and the oil tube y that is connected
between the oil terminal and the oil outlet so that they do not touch the pulse motor (for presser lifter).
Install the oil tube !2 that is connected to the oil terminal and the plunger pump with tube support M !3 and the screw
!4, pass it through the arm hole !5, and then secure it to the arm with the fastening band !6. At this time, bind the oil
tube carefully so as not to break it.
LH4-B800E
3 - 27
3. ASSEMBLY
Oil terminal mechanism
y
e
!5
t
q
r
!0
w
eq
!1
w
@8
5 mm
@5
w
@4 !0
@0
@3
@1
@2
!6
!7
u
@4
!8
!9
!0
i
o
@7
@6
w
!1
Pass the wick e through the collar q, and then insert it into the oil terminal w so that it protrudes by approximately 5
mm. Insert the packing r into the oil terminal w, and then install the oil cap t. Pass the wick e through oil pipe B y,
and then install it to the oil terminal w.
Push the oil tube u that is connected between the oil terminal and the plunger pump into the oil terminal w.
Push the oil tube !1 that is connected between the oil terminal and the oil outlet into the oil terminal w.
Install the tube support i to the wick base support !0 with the screw o.
Attach the oil tube !1 to the tube support i, and then install the oil terminal w to the wick base support !0 with the two
screws !5.
Pass the wick !6 from the needle bar bracket, the wick !7 from the bush and the wick !8 from the support shaft through
the oil tube @5, and then install felt base A !9 to the wick base support !0 with the screw @0.
Install the oil tube @1 for lubricating the bush and the zigzag lever shaft and the oil tube @2 for lubricating the zigzag
mechanism with the fastening band @3, and then install them to the wick base support !0.
Install felt base A !9 with the screw @4. Insert the felt @8, and then install the cap @6 with the screw @7.
3 - 28
LH4-B800E
3. ASSEMBLY
Plunger pump mechanism
r
w
(A)
w
q
q
e
t
io!0
o!0
i
r
!4
!1
i
o!0
!6
!5
!7
!2 !3
!1
u
u
y
r
@2
!8
!9
@0
@1
@2
!9
@0
Check that the notches (A) of the plungers q and the lower shaft w are aligned, and then insert the two plungers q
and the two compression springs e into the bush r and secure them with the two screws t.
Insert the oil tube y into the lubricating hole to the right of the bush r. Insert the oil tube u that is connected between
the plunger and the filter into the lubricating hole to the left of the bush r.
Insert the oil tube !1 into the lubricating hole to the right of the bush r. Pass the outlet of the oil tube !1 through the
tube support !2. Secure the tube support !2 to the bed with the screw !3. Insert the oil tube !4 that is connected
between the oil terminal and the plunger pump through the lubricating hole to the left of the bush r.
Pass the oil tube !6 that is connected between the oil terminal and the oil outlet through tube support D !5. Secure
tube support D !5 to the bed with the screw !7.
Secure the four tubes that are coming out from the bush r to the bed in two places as shown in the illustration with the
cord holder i, screw o and plain washer !0.
Install the pump filter !8 to the oil filter bracket @1 with the two springs !9 and the two screws @0.
Insert the oil tube oil tube u that is connected between the plunger and the filter through the oil filter bracket @1. Install
the oil filter bracket @1 to the bed with the three screws @2.
LH4-B800E
3 - 29
3. ASSEMBLY
Rotary hook lubrication mechanism
q
q
i
w
y
u
Knot
u
e
w
r
q
o !0 !1
e
!1
!0
t
o
r
Pass the wick q through the collar w as shown in the illustration.
Place the collar w onto the bush e as far as the base of the hollow. Insert the spring r into the bush e, and then
insert the wick q as shown in the illustration.
Push the end of the felt t into the hole in the bush e and stop it from turning.
Install the felt support y to the bed with the two screws u.
Pass the wick q through the felt support y and tie a knot in it. Pass the wick i through the felt support y and then
tie a knot in it.
Insert the rubber presser o into the bed, and then secure it with the spring !0 and the screw !1.
As a guide to the rotary hook lubrication amount, fully tighten the screw !1, and then loosen it by about two turns.
To check and adjust the lubrication amount, refer to "4-22. Adjusting the rotary hook lubrication".
3 - 30
LH4-B800E
3. ASSEMBLY
3-15. Rotary hook mechanism
e
q
r
t
y
r
(Screw stop side)
w
(A)
(B)
Install the rotary hook joint assembly q to the lower shaft, and then secure it by tightening the set screw w. Tighten
the set screw r so that the lubrication port (A) of the hook e and the lubrication port (B) of the rotary hook joint
assembly q are aligned. Then adjust the needle clearance and timing. Install the rotary hook holder t with the two
screws y.
LH4-B800E
3 - 31
3. ASSEMBLY
3 - 32
LH4-B800E
4. Adjustment
4. ADJUSTMENT
Notes on making adjustments
[When turning on the power to make adjustments]
1. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot before carrying out adjustments.
“Adj” will appear in the numeric display and the machine will not operate even if the treadle is pressed.
* Some items are adjusted without the RESET key being pressed. Carry out the adjustment by following the
explanations given.
[When turning off the power to make adjustments]
* Do not force any of the parts to move, as doing so may result in damage to the parts.
1. Be sure to turn the machine pulley to raise the needle bar to its highest position before making adjustments.
* If this is not done, the pulley position (the direction of rotation of the rotary hook) may cause the lower thread
trimmer mechanism to touch the rotary hook when the lower thread trimmer mechanism operates.
2. When turning the machine pulley, do it at a position where the thread trimmer mechanism will not operate (the
position where the presser foot pulse motor is at the home position).
* If the machine pulley is turned at a position where the thread trimmer mechanism operates, the needle may
touch the lower thread trimmer mechanism (lower thread retainer and lower thread trimmer knife).
* If the machine pulley is turned at a position where the thread trimmer mechanism operates, the rotary hook
and the lower thread trimmer mechanism may touch.
3. When moving the feed mechanism, do it at a position where the thread trimmer mechanism will not operate (the
position where the presser foot pulse motor is at the home position).
* If this is not done, the lower thread retainer and the feed guide shaft may alternately push against the lower
thread clamp and the opening plate, and damage may result.
4. When pushing the knife down by hand, be careful not to let it touch the upper thread scissors.
5. Do not move the feed mechanism while the stop plate of the upper thread trimmer lever is pulled forward and the
upper thread scissors are open (the upper thread trimmer lever is pushed to the left).
Always return the stop plate to its original position before moving the feed mechanism or returning it to the home
position.
Presser foot lifter pulse motor and feed pulse motor home
position (sewing start position)
Fig. A
Fig. B
w
When the stop plate w of the upper thread trimmer lever
q is pulled forward from the position in diagram (A), the
upper thread trimmer assembly e moves in the direction
of the arrow (a) and goes below the projection of the opening cam r.
q
Pulled forward
r
(a)
e
(b)
Fig. C
r
(c)
yt
Them when the feed mechanism is operated (arrow (c)),
the scissors assembly e is forced to go behind the opening cam r. Depending on the case, the rising section y
of scissors M t goes into the hollow shown in the diagram and the feed mechanism cannot then operate. At
this time, when feed mechanism home positioning is carried out, the feed pulse motor goes out of step.
* Operate the feed mechanism when the condition is
as shown in diagram A.
If it is pushed in the direction of arrow (b) at the condition shown in diagram B, the condition will change to
that shown in diagram A.
LH4-B800E
4-1
4. Adjustment
4-1. Adjusting the needle zigzag home position sensor position
q
Reference value
Needle moves
to the left
Needle bar
Presser bar
Needle moves
to the right
18.52 mm
w
e
y r
t u
1. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
2. If the needle is in the center of the needle plate hole, the following adjustment is not necessary. If the needle is not
in the center of the needle plate hole, turn off the power.
3. Loosen the screw q, and then adjust the vertical position of the needle zigzag sensor assembly w.
* The adjustment required is only slight, so move the needle zigzag sensor assembly w a little bit at a time.
4. Repeat the procedure from step 1.
* After adjusting, check that the needle bar bracket e and the stopper screws r and t are not touching when
in test feed mode. If the are touching, adjust the stopper screws r and t.
If the needle bar is at its furthest zigzag position, place the stopper screws r and t against the needle bar
bracket e, and then turn then back about 1/4 of a turn. Then tighten the nuts y and u.
4-2
LH4-B800E
4. Adjustment
4-2. Adjusting the feed home position sensor position
w
(1.5)
q
2 mm
q
w
e
r
1. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
2. If the clearance between the feed arm support q and the linear bushing w is 2 mm, the following adjustment is
not necessary. If the clearance is not 2 mm, turn off the power.
3. Loosen the screw e and adjust the position of the feed sensor support plate r.
4. Repeat the procedure from step 1.
LH4-B800E
4-3
4. Adjustment
[-5 specifications (long-hole specifications)]
w
q
q
w
r
e
1. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
2. If the clearance between the feed arm support q and the bed processed surface w is 2 mm, the following
adjustment is not necessary. If the clearance is not 2 mm, turn off the power.
3. Loosen the screw e and adjust the position of the feed sensor support plate r.
4. Repeat the procedure from step 1.
4-4
LH4-B800E
4. Adjustment
4-3. Adjusting the presser foot home position sensor position
(A)
Approx. 1 mm
r
e
y
t
q
q
w
1. Turn on the power.
* Do not set the sewing machine to the home position.
2. Move the trimmer driving arm w in the direction of the arrow to move the upper thread trimmer driving link q until
it is stopped by the face plate.
3. Loosen the screw e, and then move the dog r by approximately 1 mm in the direction of the arrow past position
(A) where the work clamp sensor turns on (the work clamp sensor LED lights). (This is the provisional position for
the work clamp home position sensor. The final position is determined when making the adjustment in "4-13-8.
Adjusting the upper thread scissors opening timing".)
4. Set the sewing machine to the home position, and then press the RESET key. Check that there is no impact noise
and that the motor does not go out of step when the presser foot is lowered.
* If the adjustment is not correct, the presser foot may touch the upper thread trimmer driving link q and the roller
y of the thread trimmer drive lever t, and this may cause the motor to go out of step.
* Make this adjustment before carrying out "4-13. Adjusting the upper thread trimming".
* After making this adjustment, check the tension release of the tack tension control and the upper thread trimming,
and adjust if necessary by referring to the respective adjustment procedures.
LH4-B800E
4-5
4. Adjustment
4-4. Adjusting the needle bar height
e
Needle bar
Cutter
0.3 mm
w
O.K.
r
t
q
NG
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Move the needle bar q to its lowest position. (Check that the needle is in the center of the needle hole. If adjustment is necessary, make the adjustment while referring to "4-1. Adjusting the needle zigzag home position sensor
position".)
2. Remove the rubber cap w from the face plate, and then loosen the set screw e of the needle bar clamp.
3. Insert the “1” part of the gauge r between the needle plate t and the lower edge of the needle bar q, and move
the needle bar q so that it touches the gauge r.
* Different gauges are used for each of the three sub-classes -2, -3 and -5, so make sure that the gauge being
used matches the specifications and application for the sewing machine being adjusted.
4. Tighten the set screw e.
5. Install the rubber cap w.
* Check that the knife flank of the needle bar is at a right angle to the knife. If the installation positions are not
correct, the needle bar and knife may touch when the needle zigzags, which may result in noise or cause the
needle to break.
4-5. Adjusting the needle and rotary hook timing
e
r
0.01 - 0.08 mm
i
y
u
t
Lowest
position
o
q
w
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the two set screws w of the rotary hook joint q.
2. Turn the machine pulley in the regular direction of rotation (toward the front) so that the needle bar e just begins
to rise from its lowest position.
3. Insert the “2” part of the gauge r between the needle plate t and the lower edge of the needle bar e, and then
align the rotary hook point y with the center of the needle when the needle bar contacts the gauge.
* Different gauges are used for each of the three sub-classes -2, -3 and -5, so make sure that the gauge being
used matches the specifications and application for the sewing machine being adjusted.
4-6
LH4-B800E
4. Adjustment
Adjusting the clearance between needle and hook point
0.01 - 0.08 mm
w
e
q
r
Loosen the screws e and move the rotary hook r forward or back until there is a clearance of 0.01 to 0.08 mm
between the needle q and the hook point w.
Needle plate thickness
Application
Gauge
S13595-001 Gauge 815-2
(-2)
13.5
+0.1
0
1
Clothing
-2
2
Knitted
wear
16
+0.1
0
S13596-001 Gauge 815-3
Knitted
wear
12.7
+0.1
0
1
3.2 mm
-3
(-3)
2
16.2
+0.1
0
2
16.7
+0.1
0
S13597-001 Gauge 805-2
tions
(-5)
2.5 mm
14.2
+0.1
0
1
Long-hole
specifica-
805-2
Thin knitted
wear
LH4-B800E
4-7
4. Adjustment
4-6. Adjusting the inner rotary hook and rotary hook holder overlap
q
A
e
w
1. Loosen the screw e to adjust so that the tip of the rotary hook holder q does not protrude past edge A of the inner
rotary hook w.
4-7. Adjusting the presser foot pressure
w
q
A
1. The standard distance A is 30 mm (approximately 30 N).
2. Loosen the nut q and turn the pressure adjusting screw w to adjust the presser foot pressure.
* When the rpessure ajusting screw w is tightened as far as it will go, the presser foot pressure will be about 70 N.
4-8. Adjusting the work clamp lift amount
w
e
q
10
10 mm
Turn on the power and set the sewing machine to the home position before making this adjustment.
1. Check that memory switch No. 05 (presser foot height at neutral position) is set to 10 mm. (If it is not set to 10 mm,
set it to 10 mm.)
2. Place a 10 mm gauge under the work clamp q and then loosen the screw w to make the adjustment.
* Adjust the lift amount (including the play in the work clamp q and the pin e to 10 mm. If it is set to more than 10
mm, the work clamp will start lifting before lower thread trimming is complete, which may result in thread trimming
errors. Furthermore, it may also cause the presser foot lifter pulse motor to go out of step.
4-8
LH4-B800E
4. Adjustment
4-9. Adjusting the work clamp lateral position
w
q
e
1. Loosen the set screw q, and then move the feed arm w and the roller e to adjust so that the knife groove comes
to the center of the work clamp window.
* After adjusting, operate the presser foot lifter pedal and check that the work clamp moves up and own smoothly.
* After adjusting, check the upper thread trimmer mechanism and adjust if necessary.
4-10. Adjusting the knife home position sensor position
4.5
0.5 mm
r
r
w
e
q
q
1. Loosen the screw q, and then adjust the knife sensor assembly r so that there is a clearance of 4.5 ± 0.5 mm
between the side of the sensor w and the edge of the solenoid stopper e.
LH4-B800E
4-9
4. Adjustment
4-11. Adjusting the knife installation position
q
w
w
Push
Pulled forward
(Fig. B)
(Fig. A)
u
Knife groove
t
Cutter
y
e
r
0.3 mm
Y
X
i
Touching
Adjust so that the upper thread trimmer knife and the cutter do not touch when the cutter is pushed down by hand.
If the upper thread trimmer knife extends below the cutter, pull the stop plate q forward and move the upper thread
trimmer assembly w to the left. (Fig. A → Fig. B)
1. Loosen the screw e, and adjust the cutter Y direction using cutter holder DL r so that the clearance between the
needle bar and the cutter is 0.3 mm. (When replacing the cutter, be careful not to allow the cutter to touch the
needle bar because of any play in the cutter installation position.)
In addition, loosen the screw t and adjust the cutter X direction using cutter holder M y so that the cutter goes
into the center of the cutter groove. Loosen the screw u and move the cutter holder to adjust the direction of
rotation.
* When the screw u has been loosened, check that the edge of the cutter holder is touching the stepped section of
the cutter driving shaft i, and then tighten the screw u.
* After adjusting, push the upper thread trimmer assembly w back to its original position (Fig. A).
4 - 10
LH4-B800E
4. Adjustment
<When using the special needle plate (needle plate -RB)>
q
w
The special needle plate has a narrow cutter groove of 0.3—0.4 mm, so use the accessory positioning plate q to
adjust the cutter installation position.
Furthermore, install the cutter holder w to minimize any play in the cutter during cutting.
* If the above adjustment is not made, the cutter may touch the needle plate, and damage to the cutter may result.
* The special needle plate is used to prevent the cutter from getting stuck in the material and not returning.
4-12. Adjusting the cutter installation height
w
e
q
Lowest
position
1.5 - 2 mm
Lowest
position
Top of needle plate
Top of needle plate
Adjust so that the upper thread trimmer knife and the cutter do not touch when the cutter is pushed down by hand.
If the upper thread trimmer knife extends below the cutter, pull the stop plate q forward and move the upper thread
trimmer assembly w to the left. (Fig. A → Fig. B)
1. Install the cutter with the screw w so that the top q of the cutter blade is aligned with the top of the needle plate
when the cutter is pressed down by hand to its lowest position.
For the flat cutter e, install with the screw w so that the top q of the cutter blade is 1.5—2 mm above the top of
the needle plate.
* After adjusting, push the upper thread trimmer assembly w back to its original position (4-11 Fig. A).
LH4-B800E
4 - 11
4. Adjustment
Adjusting the presser foot home
position sensor position 4-3
Adjusting the longitudinal feed arm
assembly position 4-13-1
Adjusting the trimmer driving arm
assembly position 4-13-2
Adjusting the lateral position of the upper thread
scissors at the sewing start 4-13-3
Adjusting the longitudinal position of the upper
thread scissors 4-13-4
Adjusting the cutting depth of the upper thread
scissors 4-13-5
Adjusting the installation height of the upper
thread scissors 4-13-6
Adjusting the upper thread scissors gradual
opening timing 4-13-7
Adjusting the upper thread scissors opening
timing
4-13-8
4 - 12
When the opening timing of the upper
thread scissors has been changed
When the gradual opening timing of the
upper thread scissors has been changed
When the installation height of the upper
thread scissors has been changed
When the cutting depth of the upper thread
scissors has been changed
When the longitudinal position of the upper thread scissors has been changed
When the lateral position of the upper
thread scissors has been changed
When the trimmer driving arm position has
been changed
When the longitudinal feed arm position has
been changed
When the home position sensor position
has been changed
Upper thread trimming adjustment procedure
When adjusting for the first time
4-13. Adjusting the upper thread trimming
(1) (1)
(2) (2) (1)
(3) (3) (2) (1)
(4)
(1)
(5)
(1)
(6)
(1)
(7)
(1)
(8) (4) (3)
(2) (2)
(9) (5) (4)
(3)
LH4-B800E
(1)
(1)
4. Adjustment
The following should be checked before adjusting the upper thread trimming.
Check the presser foot home position sensor position
Refer to “4-3. Adjusting the presser foot home position sensor position”.
4-13-1. Adjusting the longitudinal feed arm assembly position
e
r
w
q
Aligned
1.
2.
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
Check that the slot at the bottom of the upper thread trimmer lever set q is aligned with the edge of the washer
w. If they are not aligned, loosen the bolt e and move the longitudinal feed arm assembly r back and forth to
adjust.
4-13-2. Adjusting the trimmer driving arm assembly position
t
e
w
r
q
1 mm
q
w
r
e
2.
1 mm
e
wr
1.
w
r
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
Check that the overlap between the stopper w which prevents the trimmer driving arm assembly q from turning
and the stop plate r of the upper thread trimmer lever set e is 1 mm.
If adjustment is necessary, loosen the bolt t and move the trimmer driving arm assembly q back and forward
to adjust.
LH4-B800E
4 - 13
4. Adjustment
4-13-3. Adjusting the lateral position of the upper thread scissors at the sewing start
e
Approx. 1 mm
w
q
e
1. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
2. Loosen the screw q, and then move the stopper e in and out to adjust so that the edge of the upper thread
scissors w protrudes by approximately 1 mm from the center of the cutter.
* If the amount of protrusion of the upper thread scissors w is too great, the scissors may touch the needle when
they open.
* When this adjustment is carried out, also carry out the checks and adjustments in "4-13-8. Adjusting the upper
thread scissors opening timing".
4-13-4. Adjusting the longitudinal position of the upper thread scissors
Aligned
q
r
w
e
1. Turn off the power (with the feed mechanism at the home position), and then slowly move the trimmer driving arm
q forward until the upper thread trimmer assembly w is at the position shown in the illustration.
2. Loosen the screws e, and then move the upper thread trimmer assembly w back and forward to adjust so that
the front ridge line of upper thread trimmer U r is aligned with the edge of the needle hole.
* If the above adjustment is not carried out, it may result in thread trimming errors or needle breakages.
4 - 14
LH4-B800E
4. Adjustment
4-13-5. Adjusting the cutting depth of the upper thread scissors
q
q
e
Cam
w
u
t
e
y
Clearance 0--0.5 mm
r
1. Turn off the power (with the feed mechanism at the home position), and then slowly move the trimmer driving arm
q forward until the driving arm roller e is at its highest position on the cam of the upper thread trimmer lever w.
2. Loosen the screw r, and then adjust the driving arm roller e so that the clearance between the stopper y of the
upper thread trimmer assembly t and the opening cam bracket u is 0—0.5 mm.
* If the stopper y is adjusted so that it presses too firmly, it may cause the presser foot lifter pulse motor to go out
of step.
LH4-B800E
4 - 15
4. Adjustment
4-13-6. Adjusting the installation height of the upper thread scissors
q
q
Cam
w
e
w
u
r
t
1 mm
y
u
1 mm
1. Turn off the power (with the feed mechanism at the home position), and then slowly move the trimmer driving arm
q forward until the driving arm roller w is at its highest position on the cam of the upper thread trimmer lever e.
2. Loosen the screw r, and then move the upper thread scissors t up or down to adjust so hat the clearance
between the upper thread scissors t and the work clamp y is approximately 1 mm.
NOTE:
The work clamp y will tilt when sewing material joints, so adjust so that the upper thread scissors t do not touch the
work clamp y. If the upper thread scissors t are touching the work clamp y, it may cause the presser foot lifter pulse
motor to go out of step.
* If the tilting of the work clamp y causes skipped stitches to occur when sewing material joints, use the accessory
auxiliary sheet u as shown in the illustration.
4 - 16
LH4-B800E
4. Adjustment
4-13-7. Adjusting the upper thread scissors gradual opening timing
Starts touching at 1.5—2.5 mm
(B)
w (C)
(a)
0.5 mm
(A)
q
0.5 mm
e
(b)
r
q
0.5 mm
(a)
r
w
(A)
0.5 mm
(b)
(B)
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the screws q, and then adjust so that the distance (a) between ridge line (A) on the opening cam w and
the upper thread scissors e is 0.5 mm, and so that ridge line (A) on the opening cam w is parallel to the feed
direction.
2. Loosen the screw r, and then adjust so that the distance (b) between the rising section (B) of the upper thread
scissors e and the tip of the opening cam w is approximately 0.5 mm when the upper thread scissors e are
closed. If you would like the scissors to start opening earlier, make the distance smaller. However, if the distance
is too small, check that the work clamp does not touch the rising section (B) of the upper thread scissors e or the
opening cam w when it is lowered and prevent the upper thread scissors e from opening.
* Check that the upper thread scissors e gradually start opening after the material has been fed by 1.5—2.5 mm.
* Apply grease to edge surface (C).
LH4-B800E
4 - 17
4. Adjustment
4-13-8. Adjusting the upper thread scissors opening timing
Approx. 2 mm
q
t
r
e
o
w
Approx. 1—1.5 mm
i
w
e
Approx. 1—1.5 mm
Approx. 1—1.5 mm
e
Approx. 2 mm
w
t
y
r
q
(A) 5.5 - 6 mm
u
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the screw q, and then adjust the support plate r so that the back plate w and the cam e overlap by
approximately 1—1.5 mm.
If the amount of overlap is too small, the upper thread scissors will not open properly and the upper thread
scissors and the cutter may touch each other.
2. Loosen the screw t to adjust so that the clearance between the back plate w and the cam e is approximately 2
mm. Reduce this clearance if you would like the upper thread scissors to open more quickly.
3. Check that the distance (A) between the upper thread scissors y and the center of the needle u is 5.5—6 mm.
* If the distance (A) is less than about 4.5 mm, the upper thread scissors y may touch the needle when they
open, which may result in needle breakages.
If the distance (A) is outside the range of 5.5--6 mm, loosen the screw i and move the dog o in the direction
of the arrow slightly. Then tighten the screw i, turn the power back on, set the sewing machine to the home
position nd then press the RESET key to check the adjustment.
4. Check the operation in test feed mode.
* Refer to the operating procedure given in “1-10. Upper thread trimmer mechanism”.
4 - 18
LH4-B800E
4. Adjustment
4-14. Adjusting the lower thread trimming
4-14-1. Adjusting the lower thread trimmer fixed knife engagement amount
y
1 mm
y
q
(B)
e
(A)
e
w
r
t
Lower thread trimming complete
1. With the power turned off, move the lower thread trimmer cam lever q in the direction of the arrow so that the knife
driving lever w is in the position shown in the illustration. Check that the cam (A) of the movable knife e is sitting
securely on top of the cam (B) of the base plate r.
2. Loosen the screw t, and then adjust so that the fixed knife y and the movable knife e are engaged by approximately 1 mm.
* If the engagement amount is too small, the lower thread may not be fully cut, and the material may get caught
when it is removed after sewing.
4-14-2. Adjusting the lower thread retaining amount
w
(A)
w
Smaller
q
(B)
1 - 2 mm
(A)
(B)
Larger
e
e
1. Turn on the power and set the sewing machine to the home position.
2. Loosen the screw q, and then adjust the lower thread retainer w to a distance of 1—2 mm as shown in the
illustration.
* If the lower thread retaining amount has been reduced, check that the roller (B) of the lower thread clamp plate e
is sitting securely on top of the lower thread retainer cam (A).
* If the lower thread is pulling up at the first stitch at the sewing start, check if the lower thread is being pulled out of
the lower thread clamp plate e, and that it is not too loose when it is coming out from the bobbin case.
<If the lower thread retaining amount is too small>
The lower thread will pull out of the lower thread clamp plate e at the first stitch at the sewing start, which can
cause problems such as lower thread cast-off, lower thread loops or poor lower thread winding.
<If the lower thread retaining amount is too great>
This can cause problems such as poor sealing at the sewing start, or wound lower thread sticking out of the rear
tack.
LH4-B800E
4 - 19
4. Adjustment
4-14-3. Adjusting the lower thread clamp opening timing
r
q
e
w
t
Reference line A
r
q
6 - 7 mm
w
e
t
Sewing start
Lower thread winds around seam
Lower thread releases from lower thread clamp
t
Carry out the adjustment in "4-2. Adjusting the feed home position sensor position" before carrying out this adjustment.
1. Loosen the set screw w of the feed arm support q, and then align reference line A of feed guide shaft B e with
the edge of the feed arm support q. When the feed mechanism moves by 6—7 mm, the opening plate r moves
and the lower thread lamp t opens. To change the opening timing, loosen the set screw w and move feed guide
shaft B e to the left or right.
* The end of the thread which is being held by the lower thread clamp t is wound around inside the seam. If the
opening timing is too early, it can cause problems such as poor winding or pulling-up of the lower thread. If the
opening timing is too late, it can cause problems such as stretching, uneven seams or bird’s nests at the sewing
start, depending on the type of material.
4 - 20
LH4-B800E
4. Adjustment
*
After moving the lower thread trimmer cam lever y back in the direction of the arrow, move the feed mechanism.
y
If the feed mechanism is moved when the lower thread trimming has been carried out, the mechanisms will press
against each other, which may result in damage to the lower thread clamp t and the opening plate r.
r
t
LH4-B800E
4 - 21
4. Adjustment
4-14-4. Adjusting the lower thread clamp opening amount
y
Approx. 5 mm
w
t
r
e
q
1. Loosen the screws q, and then adjust so that the distance between the lower thread clamp t and the lower
thread presser y is approximately 5 mm when the feed guide shaft w is projecting out at the front and is firmly
touching the roller r of opening plate B e.
4 - 22
LH4-B800E
4. Adjustment
4-15. Adjusting the bobbin presser
w
r
A
t
e
r
q
t
u
y
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the set screw q, and then adjust the bobbin presser w so that it goes into the hole in the bobbin case e.
2. Loosen the nut r, and then turn the screw t to adjust so that the clearance A between the bobbin presser w and
the edge of the bed is approximately 12.5 mm.
* Turn off the power, move the lower thread trimmer cam lever y by hand in the direction of the arrow so that the
bobbin presser w is firmly pressing the bobbin, and then check that the lower thread retainer u is starting to hold
the lower thread.
If this timing is reversed, it will cause problems such as an excess trailing length of upper thread.
LH4-B800E
4 - 23
4. Adjustment
4-16. Adjusting the thread breakage detector
t
w
e
Touching
y
e
r
r
q
(A)
(B)
Section (B)
Section (A)
1 mm
2 mm
0.1 - 0.5 mm
e
e
1 mm
o
u
!0
w
i
1. Tighten the lever stopper q inside the slotted hole. Loosen the screw w, and then adjust so that the distance (A)
at the thread guide r is 2 mm when the thread breakage detector lever e and the lever stopper t are touching.
After adjusting, tighten the screw w.
2. Loosen the screw y of the lever stopper t, set so that distance (B) at the thread guide r is 1 mm, and then touch
the thread breakage detection lever e against the stopper t.
3. Loosen the screw u, and then change the position of the balancer i to adjust the balance between the thread
breakage detection lever e and the thread guide r.
4. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the
presser foot.
5. Loosen the screw o, and then adjust so that the thread breakage detector sensor !0 turns on (LED illuminates)
when the distance between the thread breakage detection lever e and the lever stopper q is 1 mm.
* When the thread guide r is moved to position (B) and then released, check that it moves smoothly back to
position (A).
If it does not move smoothly, check that the clearance between the thread breakage detection lever e and the
arm is 0.1—0.5 mm.
4 - 24
LH4-B800E
4. Adjustment
4-17. Adjusting the thread tension at the tack tension control
q
w
w
0.3 - 0.5 mm
0.1 - 0.3 mm
e
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the screw q, and then adjust the clearances between the tension release cam w and the tension release
pin e as shown in the illustration.
2. Press the RESET key, and check that the tension disc opening amount is 0.5—1.0 mm when the presser foot is
raised. In addition, press the RESET key once more and check that the tension discs are fully closed when the
presser foot is lowered.
4-18. Adjusting the thread tension at the zigzag tension control
w
q
Position the tension release solenoid as described in "3-5. Tension release mechanism" before carrying out this
adjustment.
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the screw q, and then move the tension stud bracket assembly w in and out to adjust so that the tension
disc opening amount is 0.5—1.0 mm.
* Check that the tension discs are fully closed when the power is turned off.
LH4-B800E
4 - 25
4. Adjustment
4-19. Adjusting the upper thread feeding amount
w
q
1. Loosen the screw q, and then turn the tension take-up lever w to adjust the upper thread feeding amount.
* Move the trimmer driving arm by hand and check that upper thread feeding is completed before the upper thread
is cut. If the above adjustment is not made, it may result in the upper thread pulling out or in upper thread clamping
errors.
4-20. Adjusting the feed timing belt
t
q
w
e
w
r
F = 98 N (10 kgf)
w
w
1. Remove the adjustment bolt q.
2. Loosen the three screws w so that the feed pulse motor e moves easily.
3. While using a spring gauge to push the notch in the motor mounting bracket r with a force of 98 N, tighten the
screws w.
4. Check that the timing belt t moves smoothly.
5. Gently tighten the adjustment bolt q.
If you do not have a spring gauge, loosen the three screws w and adjust using the adjustment bolt q. Adjust the
tension so that the amount of belt deflection is approximately 3.5 mm when a force of 5 N is applied in the middle of the
belt span.
4 - 26
LH4-B800E
4. Adjustment
4-21. Adjusting the upper shaft timing belt
e
w
A
F = 98 N (10 kgf)
q
r
1. Loosen the screws q, and then use a spring gauge to push the notch in the tension pulley plate w with a force of
98 N.
2. Tighten the screws q.
If you do not have a spring gauge, adjust the tension so that the amount of belt deflection is approximately 5 mm when
a force of 5 N is applied in the middle of the belt span between timing pulley U e and the idle pulley r in the place
indicated by arrow A.
4-22. Adjusting the rotary hook lubrication
q
w
To oil tank
More
Less
More
Less
e
1. Remove the rubber stopper q.
2. Turn the adjusting screw w to adjust the lubrication amount.
* Adjust so that approximately 10 drops of oil are released when the sewing machine is run at a speed of 4000 rpm
for three cycles to sew about 114 stitches. Use Kraft paper e or similar to catch the oil drops. As a guide, the
optimum position can be obtained if the adjusting screw is tightened as much as possible and then loosened about
two turns.
* If the lubrication amount has been reduced, run the machine for 200—300 sewing cycles and then check it again.
If lubrication stops, it will cause problems such as rotary hook seizure and thread breakages.
LH4-B800E
4 - 27
4. Adjustment
4-23. Adjusting the needle up stop position
y
e
r
q
t
w
1. The needle up stop position is adjusted so that the index mark w on the machine pulley q is inside the mark r
on the belt cover e. If adjustment is necessary, loosen the screw t of the machine pulley q and adjust the
position of the machine pulley q. The machine pulley q stops later if it is turned clockwise, and it stops earlier if
it is turned counterclockwise.
The screw y is a screw for detecting the machine stop position, and should not be loosened.
NOTE:
If the index mark w is not inside the mark r when the sewing machine is started, error code “E-02” will be displayed.
Turn the machine pulley q to move the index mark w to the correct position and then start the sewing machine.
4-24. Adjusting the V-belt tension
q
10 - 14 mm
w
1. Remove the screw, and then remove the belt cover.
2. Turn the two nuts w to adjust so that there is 10—14 mm of deflection in the V-belt q when it is pressed at the
midway point with a force of 5 N.
NOTE:
If the V-belt is too loose, or if the V-belt is stretched, the following problems could occur.
a. The stopping position may shift;
b. The needle bar may drift when the sewing machine stops;
c. An extra stitch may be sewn when the sewing machine stops;
d. An abnormal noise may be heard due to the V-belt slipping; or
e. The V-belt may become too loose and contact the cover.
If any such problems occur, adjust by following the procedure described above.
4 - 28
LH4-B800E
5. Troubleshooting guide
5. TROUBLESHOOTING GUIDE
5-1. Needle thread breakage
Cause
Needle
Threading
Check
Needle facing
Solution
Reattach needle
properly
page
As viewed from the direction of the
face plate, attach needle so that the
notched part of needle faces
frontward
(Instruction)
Needle installation
height
Install the needle at the Insert the end of the needle shank
correct height.
so that it touches the top edge of
the needle hole of the needle bar.
-
Bent needle
Replace needle
-
Blunt needle tip or burr
Replace needle
-
Needle and thread
Replace needle that fits
the thread
-
Needle thread
threading
Rethread properly
(Instruction)
Cutton, spun yarn Man-made fiber filament
yarn
(Instruction)
Bobbin thread
threading
Rethread properly
(Instruction)
Purl stitch (Seal stitch)
Whip stitch (Plain stitch)
Thread path
Flaw or abrasion on
the thread path
Polish with buff
Replace the part
Especially, pay attention to finishing
around needle plate hole
Needle plate hole
Thread
tension
Rotary hook point
Rotary hook edge
Polish with buff
Replace the part
Flaw on the rotary
hook holder
Polish with buff
Replace the part
Sub thread tension
(Zigzag chain stitch)
Adjust the needle
thread tension
1 - 2.2N tension for spun yarn #50 #60
Bobbin thread tension
Whip stitch 0.15 - 0.25N
Purl stitch 0.05 - 0.15N
(Holding the thread steady, the
bobbin case should gently descend
under the force of its own weight)
Main thread tension
Adjust the needle
thread tension
Adjust it while checking stitches
LH4-B800E
Check flaw here
Adjust the rotary hook
overlap amount.
4-8
(Instruction)
(Instruction)
5-1
5. Troubleshooting guide
Cause
Thread takeup spring
Check
Thread take-up spring
tension and stroke
Solution
Adjust thread take-up
spring tension and
stroke
tension
page
4 - 6 mm
stroke
(Instruction)
W(0.1 - 0.2 N)
Loosen the tension or shorten the
stroke to such a degree that does
not cause double hooking
Adjust it while checking bar tacking
stitches
Rotary hook
Needle height when
rotary hook point
aligned with needle
center
(Needle bar height and
needle bar rise)
Adjust its timing
Three kinds of gauges
are available
For -2, for -3 and for -5
Adjust the needle bar height to "1"
on the gauge
4-6
Gauge
Adjust needle bar height to "2" on
the gauge
2.5 mm(-2, -5)
3.5 mm(-3)
Needle
thread take
up
Gap between needle
and rotary hook
Adjust the gap
Widen the gap (0.01 - 0.08 mm) to
such a degree that rotary hook point
does not strike needle in zigzag
motion 0.01 - 0.08 mm
4-6
Rotary hook lubrication
Adjust the quantity of
lubrication oil
Too small quantity of lubrication oil
will cause thread breakage
* Check the quantity of lubrication
as follows; When the number of
stitches is about 114, sew 20
stitches and using craft paper,
check that the number of splashed
oil spots is about 10
4-27
Thread twisted around
rotary hook
Remove any twisted
thread from the inner
and outer rotary hook.
Arm thread guide
position
Adjust arm thread
guide position
-
Adjust the center of screw to the
carved mark
Carved mark
-
Gap 0.5 mm
Bobbin case
5-2
Damaged outside of
bobbin case
Bent bobbin holder
spring, etc.
Polish with buff
Replace the part
LH4-B800E
Use the B800E bobbin case.
-
5. Troubleshooting guide
5-2. Skipped stitches
Cause
Needle
Check
Needle facing
Solution
page
Refer to "5-1. Needle thread breakage"
Needle installation
height
Bent needle
Blunt needle tip or burr
Thin needle
Replace needle
Use a needle with a count that
matches the thread and material.
Thread takeup spring
Thread take-up spring
tension and stroke
Refer to "5-1. Needle thread breakage"
Upper
clamping foot
Upper clamping foot
pressure
Increase upper
clamping foot pressure
Presser adjustment screw height is
approximately 30 mm, so tighten it.
-
4-8
Approx. 30 mm
(Approx. 30 N)
Rotary hook
Relation between
upper clamping foot
and sewing length
Replace upper
clamping foot that fits
for sewing length
Blunt rotary hook point
Polish with buff
Replace rotary hook
Needle height when
rotary hook point
aligned with needle
center
(Needle bar height and
needle bar rise)
Refer to "5-1. Needle thread breakage"
When using knits or woven
materials, replace the parts with the
-3 specification parts;
Length feed plate (for subclass -3)
Upper clamping foot (for knits)
Needle plate 1.2 (for subclass -3)
-
-
Gap between needle
and rotary hook
Tension
Strength of sub thread
tension (zigzag
portion)
Adjust the upper thread
tension to the
appropriate tension.
Needle bar
play
Vertical and
longitudinal needle bar
play
Reduce the needle bar
play, or replace the
parts.
Lower thread
clamp
Lower thread retainer
cam should be sitting
firmly on lower thread
clamp plate roller.
Refer to "4-14. Adjusting the lower thread trimming"
Thread scraps and
dust blocking area
around lower thread
clamp and lower
thread presser
Clean around the lower
thread presser.
Needle plate
Material and needle
plate
When using knit
material, replace with
the -3 needle plate.
Replace with a needle
plate with a smaller
needle hole.
Using the thin -5 needle plate and
flat work clamp can be effective.
-
Joint sewing
Angle of work clamp
means that material is
not being clamped.
Replace with short
work clamp that
matches the sewing
length.
Use the accessory
auxiliary sheet.
Process the work clamp assembly
to match the joint section.
(Attach or remove rubber.)
4-16
LH4-B800E
(Instruction)
-
-
5-3
5. Troubleshooting guide
5-3. Uneven seams 1)......Beginning of sewing (1)
Cause
Upper thread
scissors
Upper thread
feeding
Check
Installation height
Solution
Install the upper thread
scissors at the correct
height.
Upper thread scissors
opening timing
Adjust to an
appropriate opening
timing.
Thread take-up
Decrease thread takeup
page
4-16
1 mm
4-17
4-18
Loosen the screw to decrease
thread take-up so that upper thread
does not pull out of scissors
assembly at the sewing start.
4-26
Screw
Less
Bobbin
thread
(bobbin slip)
Bobbin thread tension
Spring
Increase bobbin thread
tension
Apply spring
More
Bobbin thread tension
Whip stitch 0.15 - 0.25N
Purl stitch 0.05 - 0.15N
(Holding the thread steady the
bobbin case should gently descend
under the force if its own weight)
Apply spring so that the end of
the rotary hook is even with
the inside edge of the bobbin
case rim
(Instruction)
-
Make a gap
Lower thread retainer
position
Adjust lower thread
retainer position
Adjust lower thread retainer so that
a 35 - 40 mm thread leader is left
after trimming
4-19
35 - 40 mm
Bobbin presser
position
Adjust the bobbin
presser.
Bobbin insertion
Insert the bobbin
correctly.
(Instruction)
Reduce the setting for
memory switch No. 02.
(Instruction)
Presser foot lifting
speed
5-4
LH4-B800E
4-23
-
-
5. Troubleshooting guide
Beginning of sewing (2) Lower thread lifted up
*
The end of the lower thread protrudes above the seam at the sewing start
Cause
Lower thread
retainer
Check
Solution
Lower thread retaining
amount
page
Adjust the lower thread
retaining amount.
4-19
1 - 2 mm
Lower thread
clamp
Lower thread clamp
timing
4-20
Adjust so that the lower
thread clamp plate
opens when the feed
mechanism moves 6 -7 mm.
Adjust the lower thread
clamp opening timing.
Beginning of sewing (3) Seam lifts up
*
Seam lifts up and does not tighten at the sewing start
Cause
Upper thread
scissors
Check
Solution
Upper thread scissors
gradual opening timing
Adjust the gradual
opening timing of the
upper thread scissors.
page
4-17
Upper thread scissors gradually
start opening when the feed
mechanism moves about 1.5 -- 2.5
mm.
Upper thread
feeding
Refer to "5-3. Uneven seams 1)......Beginning of sewing (1)"
Beginning of sewing (4) Uneven sewing pitch
*
Bird's nests form at the sewing start, and after 5 -- 6 mm the sewing pitch suddenly increases.
Cause
Lower thread
clamp
Check
Lower thread clamp
timing
Solution
Adjust the opening
timing of the lower
thread clamp.
LH4-B800E
Advance the timing at which the
lower thread clamp starts to open.
page
4-20
5-5
5. Troubleshooting guide
5-4. Uneven seams 2)......Around rear tack or front tack
Cause
Check
Solution
Thread
release
Tension release timing
Use the parameter
switches to change the
on and off timing.
Threading
Refer to "5-1. Needle thread breakage"
Zigzag
tension
Zigzag tension disc
opening
page
(Instruction)
63
64
65
66
Adjust the opening of
the tension discs.
4-25
5-5. Uneven seams 3)......Loose thread end at end backtack (1)
Cause
Backtack
shape
Check
Solution
Check the backtack
shape
Set the value for
parameter No. 68 to
1.0.
page
When the value for parameter No.
68 is set to 1.0, the end backtack
shape changes.
(Instruction)
1.0
Thread sticking out at end backtack (2)
Cause
Check
Solution
page
Backtack
shape
Refer to "5-5. Uneven seams 3)......Loose thread end at end backtack (1)"
Uneven
material
feeding
Presser foot pressure
Increase presser foot
pressure
Upper clamping foot
When using knit
material, replace with
the -3 thread clamp
and needle plate.
Upper thread scissors
opening timing
Adjust to an
appropriate opening
timing.
4-17
4-18
Lower thread clamp
opening timing
Adjust to an
appropriate opening
timing.
4-20
4-8
Using the thin -5 needle plate and
flat work clamp can be effective.
-
5-6. Uneven seams 4)......Sticking in needle plate
*
Front and rear tack sections of material gets stuck in needle hole
Cause
Check
Start
backtack
Start backtack
Rear tack
Rear tack vector shape
Needle plate
5-6
Needle plate
Solution
Reduce the number of
front tack stitches
(parameter No. 40).
If the material is soft, setting to 0
stitches may help.
Change the rear tack
vector shape to
rectangle (parameter
No. 37).
When the rear tack vector shape is
set to rectangle, it can help to set
the tack width to a narrower width.
When using knit
material, replace with
the -3 needle plate.
Replace with a needle
plate with a 1.2 needle
hole.
Using the thin -5 needle plate and
flat work clamp can be effective.
LH4-B800E
page
(Instruction)
(Instruction)
-
5. Troubleshooting guide
5-7. Uneven seams 5)......All stitches
Cause
Threading
Check
Needle thread
threading
Solution
page
Refer to "5-1. Needle thread breakage"
Bobbin thread
threading
Needle
Needle attachment
Reattach needle
properly
Insert needle fully into needle bar
(Instruction)
Needle number count
Replace needle with
thicker one
-
Thread chips
or dust
Rotary hook rim
Rotary hook edge
Around needle plate
hole
Remove thread chips
or dust
-
Needle
thread
Needle thread tension
Increase needle thread
tension
Thread and needle
Replace needle with
one that fits for the
thread
Flaws on rotary hook
holder
Refer to "5-1. Needle thread breakage"
Rotary hook stopper
and inner rotary hook
overlap amount
Adjust the rotary hook
stopper and inner
rotary hook overlap
amount
Lubrication
Decrease the quantity
of lubrication oil
Adjust it with oil adjusting shaft
Check the quantity of lubrication as
follows; When the number of
stitches is about 114, sew 20 - 30
stitches and using the craft paper
check that the number of splashed
oil spots is about 10
Too small quantity of lubrication oil
will cause thread breakage
Adjust the tension on
the bobbin winder
guide
Decrease the tension to such a
degree that it does not cause
bobbin thread winding turbulence
Move bobbin winder
guide up and down to
adjust its position
Move it up in case (A)
Move it down in case (B)
Rotary hook
holder
Rotary hook
Bobbin
Bobbin thread tension
winder thread
guide
Uneven bobbin
winding
Adjust tension while checking
stitches
-
Stopper should not
protrude from inner
rotary hook.
(A)
Bobbin
thread
Bobbin thread tension
Adjust the bobbin
thread tension
Bobbin case
Refer to "5-1. Needle thread breakage"
Stitch
patterns
Purl stitch, Whip stitch
Parameter No. 11
setting
LH4-B800E
-
4-8
4-27
-
(Instruction)
(B)
(Instruction)
(Instruction)
5-7
5. Troubleshooting guide
5-8. Needle thread runout
Cause
Upper thread
trimmer
assembly
Check
Solution
page
Upper thread trimmer
assembly position
Move the setting plate
assembly to adjust the
scissors assembly
setting position.
(Upper thread scissors
longitudinal position
adjustment)
Upper thread scissors
cutting depth
adjustment
4-14
4-15
Operating pressure of
upper thread trimmer
assembly
Correct operating
pressure by upper
thread upper trimmer
Upper thread trimmer
driving spring
Change if transformed
End of tension release
at the beginning of
sewing
Retard the tension
release timing
Change using parameter No. 63
Opening amount of
zigzag tension discs
and bar tack tension
discs
Adjust the release
dimension
Adjust the zigzag tension discs by
moving the tension stud bracket in
and out.
Adjust the bar tack tension disc
opening amount to 0.5 -- 1 mm by
removing the top cover and moving
the tension release cam.
Adjust the operating pressure as
follows; After thread trimming, pick
the pinched thread and shake lightly
Check that the thread does not take
off upper thread trimmer assembly
-
Cotton yarn #60
Tension
release
timing
Holding force approx. 2 N
Zigzag tension
Upper thread
feeding
Needle thread take-up
Increase needle thread
take-up
Screw
LH4-B800E
More
4-25
Tack tension
Increase thread take up to a degree
that needle thread does not take off
upper thread trimmer assembly
Less
5-8
(Instruction)
4-26
5. Troubleshooting guide
Cause
Rotary hook
Check
Solution
page
Needle height when
rotary hook point
aligned with needle
center
(Needle bar height and
needle bar rise)
Refer to "5-1. Needle thread breakage"
Thread chips on rotary
hook edge
Remove thread chips
Especially, check it in case needle
thread is man-made fiber filament
yarn
Machine
stopping
position
Upper shaft pulley
stopping position
Adjust the needle up
sensor position.
Refer to instruction manual
Bobbin
thread
Lower thread retaining
amount
Refer to "5-3. Uneven seams 1)......Beginning of sewing (2) Lower
thread lifted up"
Lower thread snapping
Reduce the lower
thread retaining speed
(presser foot rise
speed).
Sewing start
speed
-
Change using the memory switch.
(Instruction)
Lower thread snapping
Lower thread retainer,
Finish so that lower thread does not
lower thread clamp and snap.
lower thread presser
plate finish
Lower thread clamp
timing
Refer to "5-3. Uneven seams 1)......Beginning of sewing (2) Lower
thread lifted up"
Slow speed
Reduce the slow start
speed.
(Instruction)
Reduce the number of
slow start stitches.
(Instruction)
Slow start stitches
Bar tack
thread
tension
Bar tack thread tension Adjust so that whip
is too strong.
stitches are formed at
the sewing start.
Upper thread
breakage
Upper thread breaks.
-
(Instruction)
Refer to "5-1. Needle thread breakage"
LH4-B800E
5-9
5. Troubleshooting guide
5-9. Unraveling of thread trimmed by upper thread trimmer assembly
Cause
Upper thread
trimmer
assembly
Check
Solution
Upper thread trimmer
assembly position
Refer to "5-8. Needle thread runout"
Burr on tips of upper
thread trimmer and
upper thread upper
trimmer
Polish with buff
Replace the part
Tension
release
timing
Opening amount for
zigzag tension discs
and bar tack tension
discs (particularly
zigzag tension discs)
Refer to "5-8. Needle thread runout"
Upper
clamping foot
Presser foot rise speed Reduce the presser
foot rise speed.
page
Check burr on upper
side here
Check burr here
Change using memory switch No.
02..
(Instruction)
5-10. Needle thread mis-trimming
Cause
Upper thread
trimmer
assembly
Check
Upper thread trimmer
assembly position
Solution
page
Refer to "5-8. Needle thread runout"
Operating pressure of
upper thread trimmer
assembly
Upper thread trimmer
driving spring
Trimmer
driving arm
5 - 10
Upper thread scissors
cutting depth
(clearance between
scissors assembly and
presser roller bracket)
Adjust the position of
the trimmer driving arm
roller.
LH4-B800E
Adjust the upper thread scissors
cutting depth.
4-15
5. Troubleshooting guide
5-11. Needle strikes upper thread trimmer
Cause
Upper thread
trimmer
assembly
Longitudinal
feed arm
Check
Solution
Upper thread trimmer
assembly position
Refer to "5-8. Needle thread runout"
Upper thread scissors
operating force
Adjust so that scissors
M open when the
projection is pressed
with a force of 4 N or
less, and remove any
scratches and burrs.
Longitudinal feed arm
position
Adjust properly
page
-
4N
Move the upper thread trimmer
driving link so that it stops at the
face plate.
In this position, tighten the eye bolt
so that the small slot in the upper
thread trimmer lever and the edge
of the washer are aligned.
4-13
Aligned
Upper thread
trimmer lever
Washer
Thread takeup position in
stopped
condition
Upper shaft pulley
stopping position
Refer to "5-8. Needle thread runout Machine stopping position"
Cam
Upper thread scissors
opening timing
adjustment
The cam should open
the stop plate properly.
Opening cam
Upper thread scissors
gradual opening timing
Refer to "4-13-7. Adjusting the upper thread scissors gradual opening
timing"
Presser foot
home
position
sensor
Presser foot home
position sensor
position
After setting to the
home position, press
the RESET key to
lower the presser foot,
and adjust so that the
distance from the
upper thread trimming
scissors to the center
of the needle is 5.5 -- 6
mm at this time.
Upper thread
trimmer lever
Upper thread trimmer
lever operating force
The upper thread
trimmer lever should
gently open when the
stop plate is separated
from the stopper.
LH4-B800E
Refer to "4-13-8. Adjusting the upper thread
scissors opening timing"
4-5
5.5 - 6 mm
-
5 - 11
5. Troubleshooting guide
5-12. Needle breakage
Cause
Needle
Rotary hook
Check
Needle facing
Needle height when
rotary hook point
aligned with needle
center
(Needle bar height and
needle bar rise)
Solution
Reattach needle
properly
page
As viewed from the direction of the
face plate, attach needle so that the
notched part of needle faces
frontward
(Instruction)
Refer to "5-1. Needle thread breakage"
Gap between needle
and rotary hook
Needle plate
Needle plate position
Adjust needle plate
front and rear position
Locate the needle at the center of
needle hole
-
Bisect
Burr on the screw hole
edge (in event of
uneven material
feeding)
Polish with buff
Check the chamfered side
finishing
(Needle plate cross section)
Upper thread
trimmer
assembly
Needle strikes upper
thread trimmer
Adjust so that the
scissors do not touch
the needle.
Cutter
Clearance between
needle bar and cutter
Install the cutter so that
the clearance between
the needle bar and the
cutter is 0.3 mm.
The cutter release
section of the needle
bar should be at a right
angle to the cutter.
Refer to "5-11. Needle strikes upper thread
trimmer"
0.3 mm
O.K.
NG
5 - 12
LH4-B800E
4-6
5. Troubleshooting guide
5-13. (1)Imperfect cutter function (imperfect material cutting)
Cause
Cutter
Check
Cutter position
Solution
Adjust cutter vertical
height
page
Install the cutter so that its edge is
aligned with the top of the needle
plate.
4-11
Aligned
Cutter blade
If the blade is worn or
chipped, sharpen it or
replace it.
Replace with the special needle
plate.
Cutter
solenoid
Check for a
disconnected cord.
Connect the cords.
Cutter power
Memory switches
Increase the setting for
memory switch No. 00.
(cutter cutting force).
Increase the setting value for
materials that are heavy or difficult
to cut.
Nut
Check for a loose nut.
Tighten securely.
Cutter sensor position
Adjust the cutter
sensor position.
Check for a loose
mounting screw.
Solenoid
stopper
(Instruction)
(Instruction)
4-9
(2) Cutter does not return
Cause
Cutter
Check
Cutter blade
Sticks in
material
Needle plate
Solution
page
If the blade is worn or
chipped, sharpen it or
replace it.
Replace with the
special needle plate.
(Instruction)
This needle plate uses the elasticity
of rubber to prevent the knife from
getting stuck and not returning. It
also helps to keep the knife blade
sharp.
4-11
(3) Cutter and upper thread scissors touch.
Cause
Upper thread
scissors
Check
Is the cam opening the
stop plate?
Solution
If the feed mechanism
operates when the cam
has not opened the
stop plate, the cutter
will bump against the
upper thread scissors.
Adjust the cam
position.
LH4-B800E
page
4-18
NG
O.K.
5 - 13
5. Troubleshooting guide
5-14. Needle thread mis-winding
Cause
Upper thread
scissors
Stitch quality
Check
Solution
Scissors installation
height
Refer to "5-3. Uneven seams 1)"
Scissors gradual
opening timing
Adjust the gradual
opening timing to an
appropriate setting.
Refer to "4-13-7. Adjusting the upper thread
scissors gradual opening timing"
Upper thread scissors
opening timing
Adjust the opening
timing to an
appropriate setting.
Refer to "4-13-8. Adjusting the upper thread
scissors opening timing"
Upper thread trimmer
movement
Polish blade of upper
thread middle trimmer
and upper thread guide
with buffer
Check for burrs on the
top surface of upper
thread middle trimmer
Change the parts
In case of dull upper thread trimmer
Refer to "5-9. Unraveling of thread
trimmed by upper thread trimmer
assembly"
Refer to "5-11. Needle strikes upper
thread trimmer"
Lateral position of
upper thread scissors
Adjust the lateral
position of the upper
thread scissors.
Needle thread tension
Decrease tension to
such a degree that it
does not influence
stitch quality
Zigzag width in the
zigzag stitch portion
Widen zigzag width to
such a degree that it
does not influence
stitch quality
Upper
clamping foot
Uneven material
feeding
Increase presser foot
pressure
(Press material so that
the material is properly
stretched)
Underlay
Underlay sewing
Reduce the setting for
the sewing start pitch
for underlay sewing
(parameter No. 52) to
around 0.5.
Reduce the underlay
sewing speed
(parameter No. 48).
5 - 14
page
LH4-B800E
Approx. 1 mm
-
4-14
(Instruction)
(Instruction)
When using knitted or woven
material, change upper clamping
foot for subclass -3 parts
Parts to change
Length feed plate (subclass -3)
Upper clamping foot assembly (for
knits)
Needle plate 1.2 (subclass -3)
4-8
(Instruction)
5. Troubleshooting guide
5-15. Folding clamp is not raised (1) Pulse motor stepping sound cannot be heard
Cause
Check
Solution
Presser foot
height setting
Check the presser foot
height setting.
Change the settings of
memory switch Nos.
04., 05. and 06..
Presser foot
lifter pulse
motor
Cord connection
Check the cord
connections and
contacts.
-
Presser lifter pulse
motor gear
Check for loose gear
set screw.
-
LH4-B800E
page
(Instruction)
5 - 15
5. Troubleshooting guide
Folding clamp is not raised (2) Pulse motor stepping sound can be heard
Cause
Check
Solution
page
Machine
stopping
position
Rotary hook touches
lower thread retainer at
the stop position
Adjust the needle up
stop position.
Presser foot
rise speed is
too fast
Memory switch No. 02.
(presser foot rise
speed)
Reduce the presser
foot rise speed.
Change using memory switch No.
02..
Upper thread
scissors
Interference between
upper thread scissors
and cloth presser
Check the standard
adjustments,
particularly for joint
sewing.
Refer to "4-13-6. Adjusting the installation
height of the upper thread scissors"
(Remove the upper thread scissors to check.)
Upper thread scissors
operation
Carry out upper thread
scissors standard
adjustments.
Interference between
fixed knife set, lower
thread clamp, lower
thread presser and
lower thread retainer.
Repair or replace the
parts.
Lower thread
trimmer
-
Retainer
Inner rotary
hook presser
(Instruction)
4-12
Lower thread
trimmer link A
-
Lower thread
trimmer
connecting rod
Remove the shoulder
screw to check.
Rubbish, dust or
thread scraps present
Remove all rubbish,
dust and thread scraps
from the lower thread
trimmer.
-
Loose screws
Check for loose screws Securely tighten all
in the upper thread
screws.
trimmer, lower thread
trimmer and presser
lifter mechanisms.
Presser foot
lifter height
Memory switch Nos.
04., 05. and 06.
Adjust so that the
memory switch setting
value matches the
presser foot rise height.
If the presser foot rise height is too
high, the lower thread trimming and
presser foot rising will become
harder and the pulse motor may go
out of step.
threading
Bobbin thread
threading
Insert the bobbin
correctly and pass the
lower thread through
the bobbin case
correctly.
If the bobbin is inserted back-tofront, it will spin loosely and the
presser lifter may go out of step.
Lower thread tension
(if the lower thread
tension is too strong,
step errors may occur)
Reduce the lower
thread tension.
Reduce the setting for
the presser foot lifting
speed (memory switch
No. 02.) to reduce the
lifting speed.
Buff this section to reduce the
thread retaining resistance.
Presser foot lifter home
position sensor
position
Adjust the presser foot
lifter home position
sensor position.
Presser foot
lifter home
position
sensor
5 - 16
LH4-B800E
-
(Instruction)
(Instruction)
-
4-5
5. Troubleshooting guide
5-16. Lower thread is not trimmed (pulls when material is removed)
Cause
Check
Solution
page
Machine
stopping
position
Rotary hook and lower Refer to "5-15. Folding clamp is not raised"
thread retainer touch at
the stop position.
Fixed knife
set
Fixed knife and
movable knife do not
mesh.
Adjust the fixed knife
Refer to "4-14-1. Adjusting the lower thread
set installation position. trimmer fixed knife engagement amount"
Knife tip is bent or
chipped.
Repair or replace the
knife.
-
5-17. Feed mechanism does not operate or motor is out of step
Cause
Check
Solution
Feed pulse
motor
Cord connection
Check the cord
connections and
contacts.
Upper thread
scissors
Upper thread scissors
position
Remove and re-install
the upper thread
scissors.
page
-
4-14
Projection on scissors M is inserted.
* Always make sure that the upper
thread scissors are in the correct
position before us.
Feed home
position
sensor
4-17
4-18
Is the cam opening the
stop plate?
If the feed mechanism
operates when the cam
has not opened the
stop plate, the feed
mechanism will go out
of step and the cutter
will bump against the
upper thread scissors.
Adjust the cam
position.
Feed home position
sensor position
Adjust the feed home
position sensor
position.
4-3
Adjust the feed timing
belt.
4-26
Feed timming Feed timing belt
belt
tension
LH4-B800E
NG
O.K.
5 - 17
5. Troubleshooting guide
5-18. Needle does not zigzag or noise occurs when needle zigzags
Cause
Check
Solution
page
Zigzag home
position
sensor
Zigzag home position
sensor position
Adjust the zigzag home
position sensor
position.
4-2
Stopper
Stopper position
Adjust the stopper
position.
4-2
5-19. Sewing machine stops during sewing
Cause
Check
Solution
Thread
breakage
detector
Thread breakage
detector position
Adjust the thread
breakage detector.
If the detector is not adjusted,
sewing may stop even when the
thread is not broken.
Emergency
stop
Panel DIP switch A-3
When panel DIP switch
A-3 is set to ON, an
emergency stop occurs
when the treadle is
depressed.
If the treadle is pressed firmly and
then released, the treadle may be
judged to have been depressed
backwards and an emergency stop
may occur.
5 - 18
LH4-B800E
page
4-24
(Instruction)
6. ELECTRIC MECHANISM
6. ELECTRIC MECHANISM
6-1. Precautions at the time of adjustment
Pay attention to the following when opening the control box for maintenance.
■ Electric shock
Some large capacitors may have a high voltage remaining in them for up to 5 minutes after the power is turned off.
To prevent electric shock, wait at least 5 minutes after the power is turned off before doing the following:
• Opening and closing the control box
• Replacing fuses
• Separating and joining connectors
• Measuring resistance
• Doing anything with a possibility of touching something inside the control box
Some adjustments require measuring the voltage while the power is turned on with the control box kept open.
In such a case, be careful not to touch any place other than that for the measurement. In addition, always keep in
mind that a high voltage remains for 5 minutes after the power is turned off.
■ Injury
While the power is turned on, the cooling fan of the control box operates; be careful not to get caught in it.
When separating or rejoining connectors, and measuring something, be careful not to cut your fingers on metal
parts such as heatsinks and covers.
LH4-B800E
6-1
6. ELECTRIC MECHANISM
6-2. Components inside the control box and the operation panel
The following are brief explanations of components inside the control box. For details on connections, refer to "6-9.
Control circuit block diagram".
- Main circuit board
This circuit board is secured to the front cover (main PCB setting plate), and it control the pulse motors and
solenoids.
- Sub circuit board
This circuit board is secured to the rear cover (auxiliary PCB setting plate), and it drives the presser foot, feed
pulse motor and cutter solenoid.
- 1-step power supply circuit board, 2-step power supply circuit board
These are secured to the bases of the first and second levels of the control box, and they generate the voltages
which are necessary for the various control operations.
- Panel PCB
The panel PCB is fixed to the front panel of the operation panel. This PCB controls indications of the machine
status and the input operation.
- DC fan motor
The DC fan motor serves as a fan to cool the inside of the control box. Clean the inlet filter monthly.
- Transformer
This is secured to the base of the second level of the control box, and it generate the voltages which are necessary for the various control operations.
Auxiliary circuit board (rear)
Panel PCB
Fan 1 (circulation)
Fan 2 (ventilation)
2-step power supply
circuit board
Transformer
1-step power supply
circuit board
Air inlet
Main circuit board
Operation panel
6-2
Control box
LH4-B800E
6. ELECTRIC MECHANISM
6-3. Fuse explanation
If a component on a PCB is damaged, a fuse may blow again immediately even when it has been replaced.
When replacing a fuse, be sure to use the specified ones listed below.
Circuit board
No.
Part code
When a fuse has blown
Voltage
F1
GFUSE8A
(glass tube fuse,
8A/250V)
S47680-000
The tension release solenoid does
not operate.
+40V
F2
GFUSEAFB
(glass tube fuse,
8A/250V(FB))
S47717-000
The zigzag motor does not operate.
DC300V
F1, F2
Fuse
15A#2
(glass tube fuse,
15A/250V)
The zigzag motor does not operate.
The tension release solenoid does
not operate.
The panel does not operate.
The control box fan does not
operate.
AC200V
F3, F4
Fuse
2A250V
(glass tube fuse,
2A/250V)
The feed motor and presser foot
motor do not operate.
The cutter solenoid does not
operate.
The panel does not operate.
DC300V
F1
G fuse 5AFB
(quick melting
type, 5A/250V)
S08030-000
The feed motor and presser foot
motor do not operate.
The cutter solenoid does not
operate.
+55V
F2
Fuse 6A
(glass tube fuse,
6A/250V)
153242-000
The feed motor and presser foot
motor do not operate.
The cutter solenoid does not
operate.
AC200V
F3
Fuse 6A
(glass tube fuse,
6A/250V)
153242-000
The feed motor and presser foot
motor do not operate.
The cutter solenoid does not
operate.
AC200V
Main circuit
board
1-step power
supply circuit
board
2-step power
supply circuit
board
Part name
218469-001
J02727-001
* F2 may also blow as a result of a malfunction of the peripheral electronic component FET.
Open the cover. The fuses are mounted to the circuit boards as shown.
1-step power supply
circuit board
Main circuit board
F2
F1
F3
F4
2-step power supply
circuit board
F1
F1
F2
F2
F3
LH4-B800E
6-3
6. ELECTRIC MECHANISM
6-4. Connectors
Most of the machine trouble is due to connector problems including improper connection or insufficient contact.
Therefore, be sure to check if each connector is correctly inserted and that there is no contact failure between pins
and wires before starting troubleshooting procedures.
■ Connector positions
Main circuit board
P16
NPM
P19
OPSOL
P15
DC300V
P20
AC17/AC30V
P1
FAN2
P3
SYNC
P22
EXPAND1
P14
AC18V
P4
PANEL
P23
EXPAND2
P13
FAN12
P10
HEAD
P11
ORG
P7
PEDAL
P9
HPEDAL
P6
POWER
Sub circuit board
P10
FAN1
P12
FAN2
P9
OPSEN1
P7
OPSEN2
P4
P3
VALV PER
P1
EXP1
P13
EXP2
P11
OPSEN1
6-4
P8
CUTTER
P6
POWER
LH4-B800E
P5
FTPM
P2
FDPM
6. ELECTRIC MECHANISM
1-step power supply circuit board
CN6
CN4 CN3 CN2
CN5
CN1
2-step power supply circuit board
P1
POWER
P4
ACIN
P3
PER
Panel PCB
P1
PANEL
LH4-B800E
6-5
6. ELECTRIC MECHANISM
Circuit board connectors
<Main circuit board>
P1 [FAN2]
Pin No.
Signal name
1
+24V
2
FAN2 signal
3
0V
Symptoms resulting mainly from poor contact
The inside air circulation fan does not operate.
Error E-41 is displayed.
P3 [SYNC]
Pin No.
Signal name
1
+5V
2
Encoder signal
3
Needle up stop position signal
4
Needle down stop position signal
5
0V
Symptoms resulting mainly from poor contact
The machine motor does not turn.
A machine stopping error occurs.
One of error E-02, E-62, E-63 and E-64 is displayed.
P4 [PANEL]
Pin No.
6-6
Signal name
1
+5V
2
0V
3
KEY0
4
KEY1
5
KEY2
6
OC
7
A
8
B
9
C
10
D
11
E
12
F
13
G
14
STB
15
P8V
16
SENSOR
17
BUZZER
18
0V
19
0V
20
0V
Symptoms resulting mainly from poor contact
The panel does not operate.
LH4-B800E
6. ELECTRIC MECHANISM
P6 [POWER]
Pin No.
Signal name
1
P8V (+8V)
2
0V
3
N8V (-8V)
4
OV. det
5
RY. out
6
OV. FAULT
7
+5V
8
PHOTO
9
U
10
V
11
W
12
U
13
V
14
W
15
IPM. FAULT
Symptoms resulting mainly from poor contact
The panel power lamp does not light.
The machine motor does not turn.
P7 [PEDAL]
Pin No.
Signal name
1
P8V (+8V)
2
PEDAL signal
3
0V
4
N8V (-8V)
Symptoms resulting mainly from poor contact
The home position can not be found.
The presser foot does not operate.
The machine does not operate.
One of error E-30, E-31 and E-32 is displayed.
P9 [HPEDAL] Standing operation pedal (option)
Pin No.
Signal name
1
P8V (+8V)
2
FORSW signal
3
BAKSW signal
4
0V
5
INCHSW signal
6
PRSW signal
7
HPEDAL signal
Symptoms resulting mainly from poor contact
The home position can not be found.
The presser foot does not operate.
The machine does not operate.
One of error E-30, E-31 and E-32 is displayed.
LH4-B800E
6-7
6. ELECTRIC MECHANISM
P10 [HEAD]
Pin No.
Signal name
1
Emergency stop NC signal
2
0V
3
Emergency stop NO signal
4
+24V
5
-
6
0V
7
+5V
8
Thread breakage detection signal
9
-
10
P8V (+8V)
11
0V
Symptoms resulting mainly from poor contact
The emergency stop switch does not operate.
The thread breakage detection does not operate normally.
P11 [ORG]
Pin No.
Signal name
1
+24V
2
Zigzag home position signal
3
0V
4
+5V
5
+24V
6
Feed home position signal
7
0V
8
+5V
9
+24V
10
Presser foot home position signal
11
0V
12
+5V
Symptoms resulting mainly from poor contact
The home position can not be found.
One of error E-05, E-06 and E-07 is displayed.
P13 [FAN12]
Pin No.
6-8
Signal name
1
+24V
2
FAN1 signal
3
0V
Symptoms resulting mainly from poor contact
The exhaust fan does not operate.
Error E-42 is displayed.
LH4-B800E
6. ELECTRIC MECHANISM
P14 [AC18V]
Pin No.
Signal name
1
AC18V (+D10V)
2
AC18V (+D10V)
3
-
4
-
5
AC18V (N)
6
AC18V (N)
7
-
8
-
9
AC18V (A)
10
AC18V (A)
11
-
12
-
13
AC18V (B)
14
AC18V (B)
15
-
16
-
17
AC18V (C)
18
AC18V (C)
19
-
20
-
21
AC18V (D)
22
AC18V (D)
23
-
24
-
25
AC18V (E)
26
AC18V (E)
27
-
28
-
29
AC18V (F)
30
AC18V (F)
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
P15 [DC300V]
Pin No.
Signal name
1
DC300V
2
DC0V
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
LH4-B800E
6-9
6. ELECTRIC MECHANISM
P16 [NPM]
Pin No.
Signal name
1
Zigzag PM driving current A
2
Zigzag PM driving current B
3
Zigzag PM driving current C
4
Zigzag PM driving current D
5
Zigzag PM driving current F
6
-
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
P19 [OPSOL]
Pin No.
Signal name
1
Spare solenoid
2
-
3
Tension release solenoid
4
-
5
+40V
6
+40V
Symptoms resulting mainly from poor contact
The tension release solenoid does not operate.
P20 [AC17/AC30V]
Pin No.
6 - 10
Signal name
1
AC30V
2
AC30V
3
-
4
AC17V
5
AC17V
Symptoms resulting mainly from poor contact
The tension release solenoid does not operate.
The control box fan does not operate.
One of error E-41 and E-42 is displayed.
LH4-B800E
6. ELECTRIC MECHANISM
P22 [EXPAND1]
Pin No.
Signal name
1
+5V
2
+5V
3
+5V
4
+5V
5
+24V
6
+24V
7
+24V
8
+24V
9
Feed PM clock
10
Presser foot PM clock
11
-
12
-
13
Presser foot PM direction signal
14
Feed PM direction signal
15
Presser foot PM current control
signal
16
Feed PM current control signal
17
PM current OFF signal
18
-
19
-
20
-
21
VALV1
22
VALV2
23
VALV3
24
VALV4
25
VALV5
26
VALV6
27
+55V OFF signal
28
+55V relay output signal
29
0V
30
0V
31
0V
32
0V
Symptoms resulting mainly from poor contact
The zigzag home position, feed home position and presser
foot home position can not be found.
The zigzag mechanism, feed mechanism and presser foot
mechanism do not operate.
One of error E-05, E-06 and E-07 is displayed.
+55 V (power supply for driving the feed mechanism and
work clamp PM) control is not possible
Error E-44 is displayed.
The valve does not operate.
LH4-B800E
6 - 11
6. ELECTRIC MECHANISM
P23 [EXPAND2]
Pin No.
Signal name
1
Input signal spare 1
2
Input signal spare 2
3
Input signal spare 3
4
Input signal spare 4
5
Input signal spare 5
6
Cutter home position sensor signal
7
Feed PM overcurrent signal
8
Presser foot PM overcurrent signal
9
+55V relay input signal
10
+55V voltage watch signal
11
-
12
-
13
0V
14
0V
15
0V
16
0V
17
-
18
-
19
-
20
-
21
Cutter return signal
22
Cutter signal
23
Cutter signal
24
Spare solenoid 1
25
Spare solenoid 2
26
Spare solenoid 3
6 - 12
Symptoms resulting mainly from poor contact
The zigzag home position, feed home position and presser
foot home position can not be found.
The zigzag mechanism, feed mechanism and presser foot
mechanism do not operate.
One of error E-05, E-06 and E-07 is displayed.
The cutter does not operate.
Error E-08 is displayed.
LH4-B800E
6. ELECTRIC MECHANISM
<Sub circuit board>
P1 [EXP1]
Pin No.
Signal name
1
+5V
2
+5V
3
+5V
4
+5V
5
+24V
6
+24V
7
+24V
8
+24V
9
Feed PM clock
10
Presser foot PM clock
11
-
12
-
13
Presser foot PM direction signal
14
Feed PM direction signal
15
Presser foot PM current control
signal
16
Feed PM current control signal
17
PM current OFF signal
18
-
19
-
20
-
21
VALV1
22
VALV2
23
VALV3
24
VALV4
25
VALV5
26
VALV6
27
+55V OFF signal
28
+55V relay output signal
29
0V
30
0V
31
0V
32
0V
Symptoms resulting mainly from poor contact
The zigzag home position, feed home position and presser
foot home position can not be found.
The zigzag mechanism, feed mechanism and presser foot
mechanism do not operate.
One of error E-05, E-06 and E-07 is displayed.
+55 V (power supply for driving the feed mechanism and
work clamp PM) control is not possible
Error E-44 is displayed.
The valve does not operate.
LH4-B800E
6 - 13
6. ELECTRIC MECHANISM
P2 [FDPM]
Pin No.
Signal name
1
Feed PM driving current A
2
Feed PM driving current B
3
Feed PM driving current C
4
Feed PM driving current D
5
Feed PM driving current F
Symptoms resulting mainly from poor contact
The feed home position can not be found.
The feed mechanism does not operate.
Error E-06 is displayed.
P3 [PER]
Pin No.
Signal name
1
Relay input signal
2
0V
3
+55V relay output signal
4
+55V OFF signal
5
0V
Symptoms resulting mainly from poor contact
The feed home position and presser foot home position can
not be found.
The feed mechanism and presser foot mechanism do not
operate.
One of error E-06 and E-07 is displayed.
+55 V (power supply for driving the feed mechanism and
work clamp PM) control is not possible
Error E-44 is displayed.
P4 [VALV]
Pin No.
Signal name
1
VALV1
2
VALV2
3
VALV3
4
VALV4
5
VALV5
6
VALV6
7
-
8
-
9
+24V
10
+24V
Symptoms resulting mainly from poor contact
(Special edition)
P5 [FTPM]
Pin No.
6 - 14
Signal name
1
Presser foot PM driving current A
2
Presser foot PM driving current B
3
Presser foot PM driving current C
4
Presser foot PM driving current D
5
Presser foot PM driving current F
Symptoms resulting mainly from poor contact
The presser foot home position can not be found.
The presser foot mechanism does not operate.
Error E-07 is displayed.
LH4-B800E
6. ELECTRIC MECHANISM
P6 [POWER]
Pin No.
Signal name
1
+55V (PM)
2
+55V (PM)
3
P0V
4
P0V
5
+24V
6
0V
7
M55V (Cutter)
8
M55V (Cutter)
9
MP0V
10
MP0V
Symptoms resulting mainly from poor contact
The feed home position and presser foot home position can
not be found.
The feed mechanism and presser foot mechanism do not
operate.
One of error E-06 and E-07 is displayed.
The cutter does not operate.
Error E-08 is displayed.
P7 [OPSEN2]
Pin No.
Signal name
1
+24V
2
+5V
3
Input signal spare 4
4
0V
5
+24V
6
+5V
7
Input signal spare 5
8
0V
9
+24V
10
+5V
11
Cutter home position sensor signal
12
0V
Symptoms resulting mainly from poor contact
The cutter does not operate.
Error E-08 is displayed.
P8 [CUTTER]
Pin No.
Signal name
1
Cutter driving current
2
-
3
Cutter return driving current
4
Cutter driving current
5
-
6
Cutter return driving current
Symptoms resulting mainly from poor contact
The cutter does not operate.
Error E-08 is displayed.
LH4-B800E
6 - 15
6. ELECTRIC MECHANISM
P9 [OPSEN1]
Pin No.
Signal name
1
+24V
2
+5V
3
Input signal spare 1
4
0V
5
+24V
6
+5V
7
Input signal spare 2
8
0V
9
+24V
10
+5V
11
Input signal spare 3
12
0V
13
0V
14
0V
Symptoms resulting mainly from poor contact
Special edition
P10 [FAN1]
Pin No.
Signal name
1
+24V
2
FAN1 signal
3
0V
Symptoms resulting mainly from poor contact
The feed pulse motor cooling fan does not spin.
P11 [OPSEN1]
Pin No.
Signal name
1
+55V
2
+55V
3
+55V
4
Spare solenoid driving current 7
5
Spare solenoid driving current 8
6
Spare solenoid driving current 9
Symptoms resulting mainly from poor contact
Special edition
P12 [FAN2]
Pin No.
6 - 16
Signal name
1
+24V
2
Spare input
3
0V
Symptoms resulting mainly from poor contact
Special edition
LH4-B800E
6. ELECTRIC MECHANISM
P13 [EXP2]
Pin No.
Signal name
1
Input signal spare 1
2
nput signal spare 2
3
nput signal spare 3
4
nput signal spare 4
5
nput signal spare 5
6
Cutter home position sensor signal
7
Feed PM overcurrent signal
8
Presser foot PM overcurrent signal
9
+55V relay input signal
10
+55V voltage watch signal
11
-
12
-
13
0V
14
0V
15
0V
16
0V
17
-
18
-
19
-
20
-
21
Cutter return signal
22
Cutter signal
23
Cutter signal
24
Spare solenoid 1
25
Spare solenoid 2
26
Spare solenoid 3
Symptoms resulting mainly from poor contact
The zigzag home position, feed home position and presser
foot home position can not be found.
The zigzag mechanism, feed mechanism and presser foot
mechanism do not operate.
One of error E-05, E-06 and E-07 is displayed.
The cutter does not operate.
Error E-08 is displayed.
LH4-B800E
6 - 17
6. ELECTRIC MECHANISM
<1-step power supply circuit board>
CN1
Pin No.
Signal name
1
P8V (+8V)
2
0V
3
N8V (-8V)
4
OV. det
5
RY. out
6
OV. FAULT
7
+5V
8
PHOTO
9
U
10
V
11
W
12
U
13
V
14
W
15
IPM. FAULT
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
The machine motor does not turn.
CN2
Pin No.
Signal name
1
AC200-R
2
AC200-T
3
-
4
-
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
The tension release solenoid does not operate.
CN3
Pin No.
Signal name
1
AC220-R
2
-
3
AC220-T
4
-
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
The tension release solenoid does not operate.
CN4
Pin No.
6 - 18
Signal name
1
AC230/240-R
2
-
3
-
4
AC230/240-T
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
The tension release solenoid does not operate.
LH4-B800E
6. ELECTRIC MECHANISM
CN5
Pin No.
Signal name
1
DC300V
2
DC0V
Symptoms resulting mainly from poor contact
The zigzag home position can not be found.
The zigzag mechanism does not operate.
Error E-05 is displayed.
CN6
Pin No.
Signal name
1
Resistance
2
Resistance
Symptoms resulting mainly from poor contact
Voltage error occurs.
Error E-95 is displayed.
LH4-B800E
6 - 19
6. ELECTRIC MECHANISM
<2-step power supply circuit board>
P1 [POWER]
Pin No.
Signal name
1
+55V (PM)
2
+55V (PM)
3
P0V
4
P0V
5
+24V
6
0V
7
M55V (Cutter)
8
M55V (Cutter)
9
MP0V
10
MP0V
Symptoms resulting mainly from poor contact
The feed home position and presser foot home position can
not be found.
The feed mechanism and presser foot mechanism do not
operate.
One of error E-06 and E-07 is displayed.
The cutter does not operate.
Error E-08 is displayed.
P3 [PER]
Pin No.
Signal name
1
Relay input signal
2
0V
3
+55V relay output signal
4
+55V OFF signal
5
0V
Symptoms resulting mainly from poor contact
The zigzag home position, feed home position and presser
foot home position can not be found.
The zigzag mechanism, feed mechanism and presser foot
mechanism do not operate.
One of error E-05, E-06 and E-07 is displayed.
+55 V (power supply for driving the feed mechanism and
work clamp PM) control is not possible
Error E-44 is displayed.
P4 [ACIN]
Pin No.
6 - 20
Signal name
1
ACIN
2
ACIN
3
-
4
EARTH
Symptoms resulting mainly from poor contact
The feed home position and presser foot home position can
not be found.
The feed mechanism and presser foot mechanism do not
operate.
One of error E-06 and E-07 is displayed.
LH4-B800E
6. ELECTRIC MECHANISM
<Panel PCB>
P1 [PANEL]
Pin No.
Signal name
1
+5V
2
0V
3
KEY0
4
KEY1
5
KEY2
6
OC
7
A
8
B
9
C
10
D
11
E
12
F
13
G
14
STB
15
P8V
16
SENSOR
17
BUZZER
18
0V
19
0V
20
0V
Symptoms resulting mainly from poor contact
The panel does not operate.
LH4-B800E
6 - 21
6. ELECTRIC MECHANISM
6-5. Description of DIP switches
6-5-1. Panel DIP switches
A
1. Slide the panel side cover to open it.
2. Change the DIP switch setting.
• Refer to the DIP switch table for an explanation of the functions of each DIP switch.
3. Slide the panel side cover downward to close it.
NOTE:
Turn the power off before changing the DIP switch settings.
If the settings are changed while the power is still on,
they will not take effect.
B
DIPSWA
1
2
3
4
No.
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
5
6
7
8
6 - 22
OFF
ON
OFF
ON
OFF
ON
OFF
Setting item
Presser foot remains lowered after sewing is complete (lifts when pedal is depressed)
Presser foot lifts after sewing is complete
Default
OFF
OFF
Emergency stop using presser foot lifter switch enabled during automatic sewing
Emergency stop using presser foot lifter switch disabled during automatic sewing
Display setting during automatic mode = lower thread counter (Default: 100)
Display setting during automatic mode = production counter (Default: 0)
2-cycle sewing ON
(All programs will be set to 2-cycle sewing regardless of the setting for parameter
No. 55.)
2-cycle sewing OFF
OFF
OFF
OFF
OFF
Upper thread breakage detection disabled
Upper thread breakage detection enabled
Programs disabled
Programs enabled
LH4-B800E
OFF
OFF
6. ELECTRIC MECHANISM
DIPSWB
No.
ON
1
OFF
ON
2
OFF
ON, ON, ON
ON, ON, OFF
ON, OFF, ON
3, 4, 5
ON, OFF, OFF
OFF, ON, ON
OFF, ON, OFF
OFF, OFF, ON
OFF, OFF, OFF
ON
6
OFF
ON, ON
ON, OFF
7, 8
OFF, ON
OFF, OFF
Setting item
Default
OFF
OFF
Work clamp size: 7.3 × 75 mm (6.0 × 70 mm)
Work clamp size: 7.3 × 36 mm (6.0 × 32 mm)
Work clamp size: 7.3 × 24.5 mm (6.0 × 20 mm)
Work clamp size: 6.8 × 36 mm (5.4 × 32 mm)
Work clamp size: 6.8 × 24.5 mm (5.4 × 20 mm)
Panel DIP switches B-7 and B-8 are enabled.
Work clamp size: 5.4 × 19 mm (4.0 × 15 mm)
Panel DIP switches B-7 and B-8 are enabled.
Needle plate size: 5.4 mm (Max. needle zigzag feed width = 4.0 mm)
Needle plate size: 7.3 mm (Max. needle zigzag feed width = 6.0 mm)
Work clamp size: 7.3 × 47 mm (6.0 × 40 mm)
Work clamp size: 6.8 × 47 mm (5.4 × 40 mm)
Work clamp size: 5.4 × 24.5 mm (4.0 × 20 mm)
Work clamp size: 5.4 × 36 mm (4.0 × 32 mm)
OFF, OFF, OFF
OFF
OFF, OFF
* If the programs are initialized when Nos. 3, 4 and 5 are set to OFF, OFF and ON (work clamp size 5.4 x
19 mm [4.0 x 15 mm]) respectively, the initial value for parameter No. 02 - Cutter size will be set to 6.0.
LH4-B800E
6 - 23
6. ELECTRIC MECHANISM
6-5-2. Control circuit board DIP switches
DANGER
Wait at least 5 minutes after turning off the power switch and disconnecting the power cord
from the wall outlet before opening the face plate of the control box. Touching areas where high
voltages are present can result in severe injury.
NOTE:
Turn the power off before changing the DIP
switch settings.
If the settings are changed while the power is
still on, they will not take effect.
e
w
q
1. Remove the six screws q, and then open the
operator's side cover w of the control box.
NOTE:
When opening the cover w, hold it securely so
that it does not fall down.
2. Change the setting of the DIP switch e.
• Refer to the DIP switch table for an explanation of the functions of each DIP switch.
3. Close the cover w of the control box, and tighten
the six screws q.
DIPSW1
1
2
3
4
5
6
7
8
6 - 24
No.
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
Setting item
Default
OFF
OFF
OFF
OFF
OFF
OFF
Three warning beeps
Continuous warning beep
Needle feed motor excitation turned off during emergency stop
and thread breakage
Needle feed motor excitation not turned off during emergency
stop and thread breakage
LH4-B800E
OFF
OFF
6. ELECTRIC MECHANISM
DIPSW2
1
2
3
4, 5
6
7
8
No.
ON
OFF
ON
OFF
ON
OFF
ON, ON
ON, OFF
OFF, ON
OFF, OFF
ON
OFF
ON
OFF
ON
OFF
Setting item
Pedal: for standing operation
Pedal: for seated operation
Starting possible only when presser foot is lowered
Starting possible regardless of presser foot position
Default
OFF
OFF
OFF
OFF, OFF
100V, 110V specifications
200V, 400V specifications
OFF/ON
OFF
OFF
LH4-B800E
6 - 25
6. ELECTRIC MECHANISM
6-6. Description of machine motor parameters
*
*
To change the machine motor parameters, press and hold the ENTER key and then turn on the power. Machine
motor parameter setting mode will then start.
Do not change the default values for the machine motor parameters unless it is absolutely necessary to do so.
No.
*
Setting items
Setting range
Unit
Default
00
Machine motor stopping position
5 - 70 (Forward for
larger values)
1
47
01
Machine motor braking force
5 - 15 (stronger for
larger values))
1
11
02
Machine motor braking time
50 - 500 ms
10
70
03
Machine motor acceleration time
5 - 70 (faster for
larger values)
1
46 (13)
04
Machine motor deceleration time
5 - 70 (faster for
larger values)
1
46
05
Machine motor stopping speed
150 - 200 rpm
10
190
06
Spare
07
Spare
08
Spare
09
Spare
If the machine motor parameters are initialized for 100 V and 110 V specifications, the machine motor acceleration time will become 13.
- The program number LED shows the machine motor parameter number.
- When a program No. key is pressed, the machine motor parameter number changes as follows.
- The value shown in the parameter display LED can be changed by pressing the parameter keys.
- The display flashes while it is being changed.
- When the ENTER key is pressed, the value appearing in the parameter display LED is accepted (the display stops
flashing).
- When the motor select key is pressed, machine motor parameter setting mode will then end and the sewing machine
will start up normally.
6 - 26
LH4-B800E
6. ELECTRIC MECHANISM
6-7. ERROR CODE TABLE
DANGER
Wait at least 5 minutes after turning off the power switch and disconnecting the power cord
from the wall outlet before opening the face plate of the control box. Touching areas where high
voltages are present can result in severe injury.
If a malfunction should occur with the sewing machine, a buzzer will sound and an error code will appear
in the display window.
Follow the remedy procedure to eliminate the cause of the problem.
For errors which do not require the power to be turned off (i.e. errors which can be reset), two short beeps
will sound. For error E-02, three short beeps will sound.
For errors which require the power to be turned off (i.e. errors which cannot be reset), a single long beep
will sound.
Code
E-00
Remedy
Cause
To restart sewing: Press the parameter down key and
EMERGENCY STOP switch was pressed.
then depress the treadle to step 2.
To cancel sewing : Press the RESET key.
E-01
To restart sewing: Press the parameter down key and
Upper thread breakage
then depress the treadle to step 2.
To cancel sewing : Press the RESET key.
E-02
Needle up sensor is OFF.
Turn the machine pully by hand to raise the needle.
E-05
Zigzag positioning is not carried out.
Turn off the power.
E-06
Feed positioning is not carried out.
Turn off the power.
E-07
Presser foot positioning is not carried out.
Turn off the power.
E-08
Cutter home position sensor is off.
Turn off the power.
E-20
Feed and presser foot motor overcurrent
Turn off the power.
E-21
Zigzag motor overcurrent
Turn off the power.
E-30
Threadle is depressed to step 2.
Return the treadle to the neutral position.
E-31
Threadle is depressed to step 1.
Return the treadle to the neutral position.
E-32
Threadle is depressed backward.
Return the treadle to the neutral position.
E-40
Control board heat sink is overheating.
Turn off the power.
E-41
Inside air circulation fan problem
Turn off the power.
E-42
Exhaust fan problem
Turn off the power.
E-44
2-step power supply circuit board +55V relay error
Turn off the power.
E-51
X pitch error
Turn off the power.
E-52
Y pitch error
Turn off the power.
E-54
Overall cycle program stitch no. error
Exceeds 3,000 stitches.
Clear the cycle program and reset automatically.
E-55
Stitch no. error
Exceeds 700 stitches. Turn off the power.
LH4-B800E
6 - 27
6. ELECTRIC MECHANISM
E-59
Sewing data error
Turn off the power.
Re-initialize the programs.
E-62
Needle up error during operation
Turn off the power.
E-63
Needle down error during operation
Turn off the power.
E-64
Timing signal error during operation
Turn off the power.
E-74
EEPROM error
Turn off the power.
E-75
RAM error
Turn off the power.
E-80
Communication ready error
Turn off the power.
E-81
Communication error
Turn off the power.
E-90
Machine motor overload
Excessive load during sewing. Turn off the power.
E-92
Machine motor operation error
Turn off the power.
E-93
Blown solenoid fuse
Turn off the power. Replace the fuse.
E-94
Machine motor IC error
Turn off the power.
E-95
Power supply voltage error (high)
Power supply voltage is too high. Turn off the power.
E-96
Power supply voltage error (low)
Power supply voltage is too low. Turn off the power.
E-97
Machine motor locked
Excessive load during sewing. Turn off the power.
ArEA
Sewing data values exceed the needle plate size or
work clamp size which have been set using the panel
DIP switches.
Three resetting methods are available depending on the application.
A. By selecting a different program number (If you would
like to keep the program which exceeds the area.)
Press the SELECT key.
Select a different program number.
Press the ENTER key.
If the data for the selected program number does not
exceed the sewing area, the error will be cleared.
B. By initializing the program
While pressing the ENTER key, press the RESET key.
* All parameters (00 to 69) for the program will then be
initialized and the machine will switch to program
mode.
C. By initializing all programs
Refer to "13. PROGRAM INITIALIZATION".
C-Er
When using the multi-working knife, the knife operation distance cannot be reduced.
Three resetting methods are available depending on the application.
A. Replace the knife with a longer knife.
Press the SELECT key to change to automatic mode.
Press the SELECT key to change to program mode.
Enter the length of the new knife as the setting for parameter 02 (Length of knife).
Press the SELECT key to change to automatic mode.
* If "C-Er" is displayed again, replace with an even
longer knife.
B. By initializing the program
Initialize only the programs which cause "C-Er" to be displayed.
While pressing the ENTER key, press the RESET key.
* All parameters (00 to 69) for the program will be initialized.
C. Change the zigzag pitch and zigzag stitch length (multiworking knife).
1. Press the SELECT key to change to automatic
mode.Press the SELECT key to change to program
mode.
2. Reduce the setting value for parameter 04 (Zigzag
pitch). Increase the setting for parameter 03 (Zigzag
stitch [multi-working knife]).
3. Press the SELECT key to change to automatic mode.
* If "C-Er" is still displayed, repeat steps 1. to 3.
6 - 28
LH4-B800E
6. ELECTRIC MECHANISM
6-8. Troubleshooting
Code
Countermeasure
E-00
1. Turn off emergency stop switch.
2. Check if connector P10 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
3. With the power turned off, separate connectors P10, and check if continuity between the
following pairs of pins 1 to 3 in the connector on the harness is as follows:
- When emergency stop switch is activated, between pins 1 and 2 is opened, and between
pins 2 and 3 is short-circuited.
- When emergency stop switch is not activated, between pins 1 and 2 is short-circuited, and
between pins 2 and 3 is opened.
* If the result of continuity test is not acceptable in either case, replace the emergency stop switch.
4. If there is still an error even after replacing the emergency stop switch, replace the main circuit
board.
E-01
1. Check if connector P10 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
2. Check the operation of the thread breakage sensor monitor lamp.
- When the dog is nearby, the monitor lamp lights.
- When the dog moves away, the monitor lamp switches off.
* If the result of continuity test is not acceptable in either case, replace the thread breakage
detection sensor.
3. If there is still an error even after replacing the thread breakage detection sensor, replace the
main circuit board.
E-02
1. Turn the pulley manually to set the needle to its highest position.
2. Check if connector P3 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
3. Replace the synchronizer.
4. If there is still an error even after replacing the synchronizer, replace the main circuit board.
E-05
1. Check if connector P11 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
2. Check the operation of the zigzag home position sensor monitor lamp.
- When the dog is nearby, the monitor lamp lights.
- When the dog moves away, the monitor lamp switches off.
* If the result of continuity test is not acceptable in either case, replace the zigzag home position
sensor.
3. If there is still an error even after replacing the zigzag home position sensor, replace the main
circuit board.
E-06
1. Check if connector P11 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
2. Check the operation of the feed home position sensor monitor lamp.
- When the dog is nearby, the monitor lamp lights.
- When the dog moves away, the monitor lamp switches off.
* If the result of continuity test is not acceptable in either case, replace the feed home position
sensor.
3. If there is still an error even after replacing the feed home position sensor, replace the main
circuit board.
LH4-B800E
6 - 29
6. ELECTRIC MECHANISM
Code
Countermeasure
E-07
<If E-07 occurs other than when machine is moving to the home position or starting>
1. Check if connector P11 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
2. Check the operation of the presser foot home position sensor monitor lamp.
- When the dog is nearby, the monitor lamp lights.
- When the dog moves away, the monitor lamp switches off.
* If the result of continuity test is not acceptable in either case, replace the presser foot home
position sensor.
3. If there is still an error even after replacing the presser foot home position sensor, replace the
main circuit board.
4. Check the sewing machine operation, particularly the operation of the upper thread trimming
mechanism, and eliminate the cause of the problem.
<If E-07 occurs when machine is starting>
1. Presser lifter pulse motor goes out of step during sewing machine operation.
Check the upper thread trimming mechanism, particularly for wear in the opening cam.
(Refer to "4-13-7. Adjusting the upper thread scissors gradual opening timing" and apply grease
to part C.)
E-08
1. Check if connector P7 on the sub circuit board is securely inserted and if any harness is
broken or short-circuited.
2. Check if connectors P23 on the main circuit board and P13 on the sub circuit board are securely
inserted and if any harness is broken or short-circuited.
3. Check the operation of the cutter home position sensor monitor lamp.
- When the dog is nearby, the monitor lamp lights.
- When the dog moves away, the monitor lamp switches off.
* If the result of continuity test is not acceptable in either case, replace the cutter home position
sensor.
4. If there is still an error even after replacing the cutter home position sensor, replace the sub
circuit board.
5. If there is still an error even after replacing the sub circuit board, replace the main circuit board.
E-20
1. With the power turned off, check for problems with feeding and check that the presser foot
moves smoothly.
2. Check if connectors P2 (feed) and P5 (presser foot) on the sub circuit board are securely
inserted and if any harness is broken or short-circuited.
* And also check if connectors P23 on the main circuit board and P13 on the sub circuit board
are securely inserted and if any harness is broken or short-circuited.
3. Replace the pulse motor that is malfunctioning.
4. Replace the sub circuit board.
E-21
1. With the power turned off, check if the zigzag mechanism moves smoothly.
2. Check if connector P16 (zigzag) on the main circuit board is securely inserted and if any harness
is broken or short-circuited.
3. Replace the zigzag pulse motor.
4. Replace the main circuit board.
E-30
E-31
E-32
1. Turn off treadle unit.
2. Check if connector P7 on the main circuit board is securely inserted and if any harness is broken
or short-circuited.
3. Replace the treadle unit.
4. If there is still an error even after replacing the treadle unit, replace the main circuit board.
E-40
1. Make sure that the control box is normally ventilated.
2. Clean the filter of the air intake. (Remove dust.)
3. Clean the cooling fan. (Remove dust.)
4. Make sure that the cooling fan is attached correctly.
E-41
1. Clean the inside air circulation cooling fan. (Remove dust.)
2. Check if connectors P13 and P20 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
3. Turn power off, check if connectors CN2, CN3 and CN4 on the 1-step power supply circuit board
are securely inserted and if any harness is broken or short-circuited.
* OK if 17 V AC is present between pins 4 and 5 of connector P20 on the main circuit board.
If not OK, replace the transformer.
4. Replace the cooling fan.
5. Replace the main circuit board.
6 - 30
LH4-B800E
6. ELECTRIC MECHANISM
Code
Countermeasure
E-42
1. Clean the exhaust cooling fan. (Remove dust.)
2. Check if connectors P1 and P20 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
3. Turn power off, check if connectors CN2, CN3 and CN4 on the 1-step power supply circuit board
are securely inserted and if any harness is broken or short-circuited.
* OK if 17 V AC is present between pins 4 and 5 of connector P20 on the main circuit board.
If not OK, replace the transformer.
4. Replace the cooling fan.
5. Replace the main circuit board.
E-44
1. Check if connector P3 on the sub circuit board is securely inserted and if any harness is broken
or short-circuited.
2. Check if connector P3 on the 2-step power supply circuit board is securely inserted and if any
harness is broken or short-circuited.
3. Check if connectors P10 and P13 on the sub circuit board are securely inserted and if any
harness is broken or short-circuited.
4. Check if connectors P22 and P23 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
5. Replace the 2-step power supply circuit board.
6. Replace the sub circuit board.
7. Replace the main circuit board.
E-51
E-52
1. Turn off the power and initialize the settings.
E-54
1. Automatically resets after 2 minutes. (Sewing data of 3,000 stitches or less will be valid, and any
sewing data past the 3000th stitch will be invalid.)
E-55
1. Turn off the power and then back on again. (Zigzagging and bar tacking will automatically be
halved, so the error display will disappear.)
2. If error E-55 appears again after the above operation is carried out, turn off the power and
initialize the settings.
E-59
1. Turn off the power and initialize the settings.
2. If error E-59 appears again after the above operation is carried out, replace the man circuit
board.
LH4-B800E
6 - 31
6. ELECTRIC MECHANISM
Code
Countermeasure
E-62
<Software>
1. If the sewing machine stops before the needle up position, reduce the setting value for machine
motor parameter No. 00 (machine motor stopping position).
2. If the sewing machine stops after the needle up position, increase the setting value for machine
motor parameter No. 00 (machine motor stopping position).
<Hardware>
1. Turn the machine pulley by hand and check if the upper shaft locks or not.
(If it locks, remove the cause of the problem.)
2. Check if connector P3 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
3. Check if the machine motor harnesses are securely inserted and if any harness is broken or
short-circuited.
4. Replace the synchronizer.
5. If there is still an error even after replacing the synchronizer, replace the main circuit board.
E-63
E-64
1. Turn the machine pulley by hand and check if the upper shaft locks or not.
2. Check if connector P3 on the main circuit board is securely inserted and if any harness is
broken or short-circuited.
3. Replace the synchronizer.
4. If there is still an error even after replacing the synchronizer, replace the main circuit board.
E-74
1. Replace the main circuit board.
E-75
1. Replace the main circuit board.
E-80
E-81
1. Make sure that ROM chips of the main circuit board are correctly inserted. (Check position,
orientation, lead clinching.)
2. Replace the main circuit board.
E-90
E-92
E-94
1. Turn the machine pulley by hand and check if the upper shaft locks or not.
2. Check if connectors P3 and P6 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
3. Check if machine motor harness connector CN7 and power supply harness connector CN8 on
the 1-step power supply circuit board are securely inserted and if any harness is broken or
short-circuited.
4. Replace the 1-step power supply circuit board.
5. Replace the main circuit board.
E-93
1. Check fuse F1 on the main circuit board.
2. If fuse F1 on the main circuit board is blown, replace it.
6 - 32
LH4-B800E
6. ELECTRIC MECHANISM
Code
Countermeasure
E-95
E-96
1. Check the power supply voltage in the workplace and the power supply voltage specifications for
the control box.
2. Check the connection positions of connectors CN1 and CN2 on the 1-step power supply circuit
board.
* 200V specification --- CN2
* 220V specification --- CN3
* 230V specification --- CN4
* 100, 110, 240, 380, 400, 415V specification --- CN3
E-97
1. Check if the timing belt is attached.
2. Turn the machine pulley by hand and check that the upper shaft does not lock and the pulley is
not loose.
3. Check if connectors P3 and P6 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
4. Check if machine motor harness connector CN7 and power supply harness connector CN8 on
the 1-step power supply circuit board are securely inserted and if any harness is broken or
short-circuited.
5. Replace the 1-step power supply circuit board.
6. Replace the main circuit board.
ArEA
Refer to "6-7. Error code table".
C-Er
Refer to "6-7. Error code table".
LH4-B800E
6 - 33
6. ELECTRIC MECHANISM
6-9. Control circuit block diagram
Control box
Synchronizer
LED0(E)
LED1(F)
LED2(G)
(STB)PLED
P8V
Sensor input
BUZZ
S0V
S0V
S0V
Thread breakage
detection sensor
Solenoid
P11
OPSOL
P14
OPPM
P6
POWER
Red
Black
White
1
2
3
4
B3B-PH-K-S
PHR-3
EARTH
U
V
W
3191-04R1
3191-04P
Green/Yellow
Red
Black
White
+24V
+5V
OPSEN1
0V
+24V
+5V
OPSEN2
0V
+24V
+5V
OPSEN3
0V
0V
0V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
3
4
5
6
7
8
9
10
VHR-10N
B10P-VH
PHR-5
B5B-PHKS
B14B-PHDSS
RLYIN
S0V
RLYOFF
SWDOFF
S0V
+55V
+55V
P0V
P0V
E24V
SOV
M55V
M55V
MP0V
MP0V
EARTH
ACIN(R)
ACIN(S)
ACIN(T)
CN8
ACIN
EARTH
ACIN
ACIN
ACIN
E2
EARTH
Earth
inductor
P1
POWER
Green/Yellow
Red
Black
White
P3
PER
POWER PCB
S50425
Green/Yellow
3191-04P
3191-04R1
CN7
1
2
3
4
5
1
2
3
4
5
6
7
8
9
10
E1
R
S
T
CN1
White
B5B-PHKS
PHR-5
P4
ACIN
P2
Red
White
Green/Yellow
PE
1
2
3
4
1 M55V
2 MP0V
5273-02A
P1
FAN2
P15
DC300V
1 DC300V
2 DC0V
CN2:AC200
CN3:AC220
CN4:AC230/240V
1 R(CN2,3,4)
Power
2 T(CN2)
transformer
3 T(CN3)
4 T(CN4)
CN5
Red
PNV
Black
P0V
Red
Red
1
2
3
4
LP-04-2V
LB-04TV
AC18F
AC18F
POWER PCB
S47722
Blue
Blue
3191-04P
3191-04R1
AC18E
AC18E
P20
AC17V/AC30V
1 AC30V
2 AC30V
3
4 AC17V
5 AC17V
U U
V V
W W
AC18D
AC18D
Orange
Orange
Yellow
Yellow
Violet
Violet
White
White
Black
Black
Brown
Brown
Gray
Gray
Green
Green
B10P-VH
VHR-10N
VAL1
VAL2
VAL3
VAL5
VAL4
VAL6
NC
NC
+24V
+24V
P4
VALV
P7
OPSEN2
P9
OPSEN1
P3
PER
+55V
+55V
P0V
P0V
E24V
SOV
M55V
M55V
MP0V
MP0V
SUB PCB
S50431
+24V
+5V
OPSEN4
0V
+24V
+5V
OPSEN5
0V
+24V
+5V
OPSEN6
0V
P12
FAN2
B12B-PHDSS
1
2
3
4
5
6
7
8
9
10
11
12
PMOUT1
PMOUT2
PMOUT3
PMOUT4
PMCOM1
PMCOM2
1
2
3
4
5
6
P10
FAN1
P6
POWER
S0V
S0V
S0V
(+24V)
(+24V)
(+24V)
(+24V)
PD2
PD3
PD4
PD5
PD6
PD7
B6P-VH
RLYIN
S0V
RLYOFF
SWDOFF
S0V
P8
CUTTER
B6P-VH
+55V
+55V
+55V
OPSOL7
OPSOL8
OPSOL9
P2
FDPM
B3B-PH-K-S
1
2
3
4
5
6
CUTTER
NC
CUT-RET
M55V-CNT
NC
+55V
1
2
3
4
5
6
P5
FTPM
PHR-3
B3B-PH-K-S
1 +24V
2 LOCK
3 S0V
Black
Red
Orange
Yellow
Blue
A
B
C
D
E
1
2
3
4
5
3191-06R
5219-06A
Red
White
Black
Black
Red
Orange
Yellow
Blue
VHR-5N
B5P-VH
A
B
C
D
E
5566-6A
5557-06R
VHR-5N
B5P-VH
DC fan
(Feed pulse motor)
1
2
3
4
5
6
7
8
9
10
P13
EXP2
1 OPSEN1 14
2 OPSEN2 15
3 OPSEN3 16
4 OPSEN4 17
5 OPSEN5 18
6 OPSEN6 19
7 OPSEN7 20
8 OPSEN8 21
9 OPSEN9 22
10 OPSEN10 23
11 OPSEN11 24
12 OPSEN12 25
13 S0V
26
Feed
pulse motor
1
2
3
4
5
PF4
PF5
PF6
PF7
PE0
PE1
PE2
PE3
PE4
PE5
PE6
PE7
S0V
S0V
S0V
S0V
Cutter
Green/Yellow
PHDR-32VS
B32B-PHDSS
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
15P-SCN
1 P8V
2 S0V
3 N8V
4 OV.det
5 RY.out
6 OV.FAULT
7 +5V
8 PHOTO
9 U
10 V
11 W
12 U
13 V
14 W
15 IPMFAULT
AC18C
AC18C
B30B-PHDSS
PHDR-30VS
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1 +24V
2 LOCK
3 S0V
B4B-PH-K-S
PHR-4
P1
EXP1
1 +5V
2 +5V
3 +5V
4 +5V
5 (+24V)
6 (+24V)
7 (+24V)
8 (+24V)
9 TOUT1
10 TOUT2
11 TOUT3
12 TOUT4
13 PF0
14 PF1
15 PF2
16 PF3
Red
White
Black
P8V
PEDAL
S0V
N8V
B4B-XHA
Black
Red
Orange
Yellow
Blue
Presser foot
pulse motor
B10B-PHD
P7
PEDAL
1
2
3
4
B3B-PH-K-S
PHR-3
Red
White
Black
B3B-XHA
P12
OPVR
Red
White
Black
Green
P13
FAN1
1 +24V
2 LOCK
3 S0V
P2
VR
+5V
IN
OUT
S0V
N8V
S0V
+5V
LTH
1 5V
2 VR
3 S0V
P5 SW(OP)
1 NIPPER
2 DIS
3 Potentio
4 Latch SDLA
5 Latch SDLB
6 W1P
7 ST/STOP
8 SAFE
9 EMG
10 TRIM
11 REV
12 TG
13 S0V
5
6
7
8
1
2
3
4
B4P-VH
P21
L-THREAD
1 FG
2
3 SENS
4 +E1
P14
AC18V
1 AC18D10
2 AC18D10
3
4
5 AC18N
6 AC18N
7
8
9 AC18A
10 AC18A
11
12
13 AC18B
14 AC18B
15
S0V
S0V
S0V
+24V
+24V
+24V
+24V
PD2
PD3
PD4
PD5
PD6
PD7
Zigzag
pulse motor
PHDR-26VS
B26B-PHDSS
P23
EXPAND2
1 OPSEN1 14
2 OPSEN2 15
3 OPSEN3 16
4 OPSEN4 17
5 OPSEN5 18
6 OPSEN6 19
7 OPSEN7 20
8 OPSEN8 21
9 OPSEN9 22
10 OPSEN10 23
11 OPSEN11 24
12 OPSEN12 25
13 S0V
26
P9 HPEDAL
1 P8V
2 FORSW
3 BAKSW
4 S0V
5 INCHSW
6 PRSW
7 HPEDAL
P17 POWER(OP)
1 +5V
2 S0V
3 +40V
4 P0V
B13B-PH-K-S
MAIN PCB
S50479
B5P-VH
VHR-5N
+24V
+24V
+5V
+5V
S0V
S0V
P8V
N8V
5219-02A
3191-02R1
9
10
11
12
13
14
15
16
PF4
PF5
PF6
PF7
PE0
PE1
PE2
PE3
PE4
PE5
PE6
PE7
S0V
S0V
S0V
S0V
1 P8V
2 S0V
3 N8V
4 OV.det
5 RY.out
6 OV.FAULT
7 +5V
8 PHOTO
9 U
10 V
11 W
12 U
13 V
14 W
15 IPMFAULT
B15B-XHA
XHP-15
P8
RS232C
1 TXD1
2 DTR1
3 RXD1
4 DSR1
5 (TXD1)
6 (DTR1)
7 (RXD1)
8 (DAR1)
B8B-XHA
B7B-XHA
B16B-PHDSS
B16B-XHA
P22
EXPAND1
1 +5V
17
18
2 +5V
19
3 +5V
20
4 +5V
5 +24V
21
22
6 +24V
7 +24V
23
8 +24V
24
9 TOUT1 25
10 TOUT2 26
11 TOUT3 27
12 TOUT4 28
13 PF0
29
14 PF1
30
15 PF2
31
16 PF3
32
Solenoid
White
B32B-PHDSS
PHDR-32VS
P11
ORG
Presser foot
home position
sensor
Tension release
Black
B26B-PHDSS
PHDR-26VS
+24V
NORG
0V
+5V
+24V
YORG
0V
+5V
+24V
HORG
0V
+5V
1
2
3
4
5
6
7
8
9
10
11
12
P3
SYNCHRO
P19 OPSOL
1 OPSOL1
2 +E1
3 OPSOL2
4 +E1
5 +40V
6 +40V
P16
NPM
1 A
2 B
3 C
4 D
5 E
6
B6B-XHA
XHP-6
Brown
Black
Blue
Brown
Black
Blue
Brown
Black
Blue
Red
White
Black
Green
Yellow
+5V
ENC
NLUP
NLDW
S0V
XHP-12
B12B-XHA
1
2
3
4
5
EMNC
S0V
EMND
+24V
Actuator
0V
+5V
Spare
GKTH
P8V
S0V
XHP-5
B5B-XHA
P10
HEAD
P4
PANEL
P18
SOL
1 P0V(BT)
2 P0V(PR)
3 BTSW
4 PRSW
5 +40V
6 Thread trimming
7 Thread wiper
8
9 Presser foot lifter
10 Thread holding
11 +40V(Presser foot lifter)
12 +40V(Thread trimming)
13 +40V
14 +40V(Thread wiper)
15 +40V(Thread holding)
16 +40V
Blue
XHP-11
B11B-XHA
XG4M-2030-T
XG4A-2031
+5V
11 LED0(E)
S0V
12 LED1(F)
13 LED2(G)
KEY0
KEY1
14 (STB)PLED
KEY2
15 P8V
16 Sensor input
OC
17 BUZZ
A
B
18 S0V
C
19 S0V
D
20 S0V
1
2
3
4
5
6
7
8
9
10
11
1
2
3
4
5
6
7
8
9
10
Black
Red
White
Black
Brown
Feed
home position
sensor
1 +24V
2 LOCK
3 S0V
XG4A-2031
XG4M-2030-T
1
2
3
4
5
Zigzag
home position
sensor
Cutter return
11
12
13
14
15
16
17
18
19
20
Green
Green/Yellow
+5V
S0V
KEY0
KEY1
KEY2
OC
A
B Operation panel
C
D
Emergency stop
Black
White
1
2
3
4
5
6
7
8
9
10
Machine head
Red
White
Black
P1
PANEL
Red
PANEL PCB
S50453
ACIN(R)
ACIN(T)
EARTH
DC fan
Leg
Power switch
Red
DC fan
White
Black
Treadle unit
Machine motor
Power supply plug
Green/Yellow
OUT220V
Red
White
Conversion
transformer
Black
Green/Yellow
IN240,380,400,415V
LH4-B800E
6 - 34
SERVICE MANUAL
BROTHER INDUSTRIES, LTD.
15-1, Naeshiro-cho, Mizuho-ku, Nagoya 467-8561, Japan. Phone: 81-52-824-2177
Printed in Japan
118-H80
I1050811H
2001.07. H (1)