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MICROWAVE OVEN
SERVICE MANUAL
MODEL: MV1526W
MV1526B
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.
CAUTION
SAFETY PRECAUTIONS
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE EXPOSURE
TO EXCESSIVE MICROWAVE ENERGY
a. Do not operate or allow the oven to be operated with the door open.
b. Make the following safety checks on all ovens to be serviced before activating the
magnetron or other microwave source, and make repairs as necessary; (1) Interlock
operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and
other damage), (4) damage to or loosening of hinges and latches, (5) evidence of
dropping or abuse.
c. Before turning on microwave power for any service test or inspection within the
microwave generating compartments, check the magnetron, wave guide or
transmission line, and cavity for proper alignment, integrity, and connections.
d. Any defective or misadjusted components in the interlock, monitor, door seal, and
microwave generation and transmission systems shall be repaired, replaced, or
adjusted by procedures described in this manual before the oven is released to the
owner.
e. A Microwave leakage check to verify compliance with the CSA Standard should be
performed on each oven prior to release to the owner.
• Proper
operation of the microwave ovens requires that the magnetron be assembled to the
wave guide and cavity. Never operate the magnetron unless it is properly installed.
• Be
sure that the magnetron gasket is properly installed around the dome of the tube whenever
installing the magnetron.
• Routine
service safety procedures should be exercised at all times.
• Untrained
personnel should not attempt service without a thorough review of the test
procedures and safety information contained in this manual.
FOREWORD
Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing
yourself to the Microwave Energy normally contained within the oven cavity.
TABLE OF CONTENTS
(Page)
SAFETY PRECAUTIONS .........................................................................................................
Inside front page
SPECIFICATIONS..........................................................................................................................................
1-1
CAUTIONS .....................................................................................................................................................
2-1
INSTALLATION ..............................................................................................................................................
3-1
OPERATING INSTRUCTIONS.......................................................................................................................
4-1
CONTROL PANEL .................................................................................................................................
4-1
CONTROL PANEL INSTRUCTIONS .....................................................................................................
4-2
OVERALL CIRCUIT DIAGRAM......................................................................................................................
5-1
SCHEMATIC DIAGRAM.........................................................................................................................
5-1
MATRIX CIRCUIT FOR TOUCH KEY BOARD ......................................................................................
5-2
GENERAL INFORMATION FOR SERVICE ...................................................................................................
6-1
GENERAL PRECAUTIONS IN USE ......................................................................................................
6-1
TRIAL OPERATION ...............................................................................................................................
6-1
FEATURES AND SPECIFICATIONS FEATURES.................................................................................
6-1
SERVICE INFORMATION .............................................................................................................................
7-1
PRECAUTIONS AND REPAIR SERVICE TIPS .....................................................................................
7-1
MICROWAVE LEAKAGE TEST .............................................................................................................
7-2
POWER OUTPUT MEASUREMENT .....................................................................................................
7-3
DISASSEMBLY INSTRUCTIONS ..........................................................................................................
7-4
INTERLOCK SYSTEM .......................................................................................................................... 7-12
INTERLOCK CONTINUITY TEST .......................................................................................................... 7-14
TEST AND CHECKOUT PROCEDURES AND TROUBLE SHOOTING................................................ 7-15
A. TEST PROCEDURES................................................................................................................ 7-15
B. CHECKOUT PROCEDURES..................................................................................................... 7-18
C. TROUBLE SHOOTING .............................................................................................................. 7-21
EXPLODED VIEW ..........................................................................................................................................
8-1
REPLACEMENT PARTS LIST ...............................................................................................................
8-8
SCHEMATIC DIAGRAM OF PCB .......................................................................................................... 8-12
PRINTED CIRCUIT BOARD .................................................................................................................. 8-13
PCB PARTS LIST................................................................................................................................... 8-14
SPECIFICATIONS
Rated Power Consumption..................................................1,500W maximum (Microwave oven+Cook top lamps+Ventilation fan)
Microwave Output.................................................................1,000W (IEC 60705)
Adjustable 100W through 1000W, 10 steps
Frequency .............................................................................2,450 MHz ± 50 MHz
Power Supply........................................................................120 VAC, 60 Hz
Rated Current .......................................................................13 Amp. (Microwave oven+Cook top lamps+Ventilation fan)
Magnetron Cooling ...............................................................Forced Air Cooling
Rectification...........................................................................Rectification Voltage Double Half-Wave
Door Sealing .........................................................................Choke System
Safety Devices......................................................................Oven Cavity Thermostat:
Open at 90°C ± 5°C
Fuse(20A)
Primary Interlock Switch
Secondary Interlock Switch
Interlock Monitor
Magnetron.............................................................................2M214-39F
High Voltage Capacitor ........................................................Capacitor: 1.0µF, 2.1 KV AC
High Voltage Diode...............................................................Diode; 350mA, 9.0 KV
Cook top Lamp .....................................................................125 V, 30 W
Cavity Lamp..........................................................................125 V, 30 W
Timer .....................................................................................Digital, up to 99 mim. 99 sec. (in each cooking stage)
Tray .......................................................................................Tempered Safety Glass
Overall Dimensions ..............................................................2915/16”(W)x167/16”(D)x153/8”(H)
Oven Cavity Size .................................................................197/8”(W)x143/16”(D)x815/16”(H)
Effective Capacity of Oven Cavity .......................................1.5 Cu.ft.
Accessories...........................................................................Owner’s Manual & Cooking Guide, Installation Manual,
Exhaust Adapter, Exhaust Damper, Mounting Kit and Two Filters,
Rotating Ring Assembly.
1-1
CAUTIONS
Unlike other appliances, the microwave oven is
high-voltage and high-current equipment.
Though it is free from danger in ordinary use,
extreme care should be taken during repair.
MICROWAVE RADIATION
Personnel should not be exposed to the
microwave energy which may radiate from the
magnetron or other microwave generating
device if it is improperly used or connection.
All input and output microwave connections,
waveguide, flange, and gasket must be secure.
Never operate the device without a microwave
energy absorbing load attached.
Never look into an open waveguide or antenna
while the device is energized.
• DO NOT operate on a 2-wire extension cord during
repair and use.
• NEVER TOUCH any oven components or wiring during
operation.
• BEFORE TOUCHING any parts of the oven, always
remove the power plug from the outlet.
• For about 30 seconds after the oven stops, an electric
charge remains in the high voltage capacitor. When
replacing or checking, you must discharge the high
voltage capacitor by shorting across the two terminals
with an insulated screwdriver.
• Proper operation of the microwave oven requires that
the magnetron be assembled to the waveguide and
cavity. Never operate the magnetron unless it is
properly installed.
• Be sure that the magnetron gasket is properly
installed around the dome of the tube whenever
installing the magnetron.
ANTENNA
Gasket
COOLING FIN
FILAMENT
TERMINALS
MAGNETRON
CHASSIS GROUND
• Remove your watch whenever working close to or
replacing the Magnetron.
• DO NOT touch any parts of the control panel circuit. A
resulting static electric discharge may damage this
P.C.B.
• NEVER operate the oven with no load.
• NEVER injure the door seal and front plate of the oven
cavity.
• NEVER put iron tools on the magnetron.
• NEVER put anything into the latch hole and the interlock
switches area.
MAGNETRON
THE OVEN IS TO BE SERVICED ONLY
BY PROPERLY QUALIFIED SERVICE
PERSONNEL.
2-1
INSTALLATION
BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.
PRECAUTIONS ON INSTALLATION
A. Plug the power supply cord into a 120V AC, 60Hz,
single-phase power source with a capacity of 15A
or 20A.
B. Avoid placing the unit in a location where there is
direct heat or splashing water.
C. Install the unit on the mounting plate firmly.
D. Place the unit as far away as possible from TV,
radio, etc. to prevent interference.
GROUNDING INSTRUCTIONS
For personal safety, this appliance must be fully
grounded at all times.
In the event of an electrical short circuit, grounding
reduces the risk of electrical shock.
The plug must be plugged into an outlet that is
properly installed and grounded.
CAUTION
This unit is equipped with a 3-prong plug for your
safety. If the wall outlet is a grounded 3-hole type,
the unit will be grounded automatically.
Plug with Ground
Prong
Properly Polarized
and Grounded
Outlet
WARNING
Improper use of the grounding plug can result in a
risk of electric shock.
Do not, under any circumstances, cut or remove the
third ground prong from the power cord plug.
3-1
OPERATING INSTRUCTIONS
CONTROL PANEL
1
2
4
3
7
5
6
10
8
9
11
12
13
14
16
15
18
17
21
19
20
4-1
CONTROL PANEL INSTRUCTIONS
12. TIME COOK: Touch this pad to set a cooking time.
1. DISPLAY: The Display includes a clock and indicators to
tell you time of day, cooking time settings and cooking
functions selected.
13. POWER LEVEL: Touch this pad to select a cooking
power level.
2. POPCORN: Touch this pad when popping popcorn in
your microwave oven.
3. POTATO: Touch this pad to cook potatoes from 1 to 4.
14. CUSTOM SET: Touch this pad to change the oven’s
default settings for sound, clock, display speed, defrost
weight, and demo mode operations.
4. BEVERAGE: Touch this pad to reheat one cup or two
cups a beverage.
15. KITCHEN TIMER: Touch this pad to set the kitchen
timer.
5. PIZZA: Touch this pad to reheat 1 to 3 slices.
16. CLOCK: Touch this pad to enter the time of day.
6. TIME DEFROST: Touch this pad to defrost most other
frozen foods.
17. FAN HI/LO/OFF: Touch this pad to turn the fan on or off.
18. LIGHT HI/LO/OFF: Touch this pad to turn on the
cooktop/countertop light.
7. FROZEN ENTREE: Touch this pad to cook frozen entrees
by choosing a preset weight.
19. STOP/CLEAR: Touch this pad to stop the oven or clear
all entries.
8. AUTO COOK: Touch this pad to cook vegetables, rice, or
casseroles.
20. EZ ON: Touch this pad to set and start quickly at 100%
power level.
9. AUTO REHEAT: Touch this pad to reheat dinner plate,
soup/sauce, casserole, roll/muffin.
21. START: Touch this pad to start a function. If you open
the door after oven begins to cook, retouch START.
10. AUTO DEFROST: Meat, poultry, fish. Touch on pad to
select food type and defrost food by weight.
11. NUMBER: Touch number pads to enter cooking time,
power level, quantities or weights.
4-2
OVERALL CIRCUIT DIAGRAM
SCHEMATIC DIAGRAM
5-1
MATRIX CIRCUIT FOR TOUCH KEY BOARD
AUTO
COOK
TIME
COOK
CUSTOM
SET
AUTO
REHEAT
AUTO
DEFROST
CLOCK
Ez On
KITCHEN
TIMER
N.C
TIME
DEFROST
POWER
LEVEL
STOP/
CLEAR
N.C
5-2
GENERAL INFORMATION FOR SERVICE
FEATURES AND SPECIFICATIONS
FEATURES
GENERAL PRECAUTIONS IN USE
A. Never operate the unit when it is empty.
Operating the oven with no load may shorten the
life of the magnetron. Whenever cooking dry foods
(dried fish, bread, etc.) or a small amount of food,
be sure to put a glass of water into the cooking
compartment. The glass turntable may become hot
after operating, be careful when touching it.
B. Aluminum foil should be avoided because it will
disrupt cooking and may cause arcing. However,
small pieces may be used to cover some parts of
food to slow the cooking. Any aluminum foil used
should never be closer than 2.5 cm to any side wall
of the oven.
A. The safety systems incorporated in this model are:
(1) Primary interlock switch
(2) Secondary interlock switch
(3) Interlock monitor switch
(4) Choke system
(5) Magnetron thermal fuse
(6) Oven cavity thermostat
(Note: This thermostat located on the oven
cavity will open and stop the unit from operation
only if a high temperature is reached, such as,
a fire created by overcooking food.)
B. Any one of 10 power output levels ranging 100W to
1000W can be selected by the touch control and
electronic computer system.
TRIAL OPERATION
After installation, the following sequences and results
should be checked carefully.
A. Put a container filled with water (about 1 liter) into
the oven, and close the door tightly.
B. Set cooking time for 10 minutes by touching “1”
and then “0” three times. “1, 0, 0, 0” appears in
the display window.
C. Touch the START key.
Make sure the cavity light comes on. The unit will
begin cooking and the display window will show the
time counting down by seconds.
D. After about 5 minutes, make sure the primary
interlock switch, the secondary interlock switch and
the interlock monitor switch operate properly by
opening and closing the door several times. Touch
the START key each time the door is closed.
E. Continue operating the unit. Four long beep sound
signal is heard when the time is up. The unit will
shut off automatically.
F. Confirm the water is hot.
G. Finally, measure the output power according to
“POWER OUTPUT MEASUREMENT” on
page 7-3.
6-1
SERVICE INFORMATION
PRECAUTIONS AND REPAIR SERVICE TIPS
PRELIMINARY
(3) Do not operate the unit until it is completely
repaired, if any of the following conditions exist.
The unit must not be operated.
(a) The door does not close firmly.
(b) The hinge is broken.
(c) The door seal is damaged.
(d) The door is bent or warped, or there is any
other visible damage on the unit that may
cause microwave energy leakage.
NOTE: Always keep the seal clean.
(e) Make sure that there are no defective parts
in the interlock mechanism.
(f) Make sure that there are no detective parts
in the microwave generating and transmission
assembly (especially waveguide).
A. SINCE NEARLY 2,100 VOLTS EXISTS IN SOME
CIRCUITS OF THIS UNIT REPAIRS SHOULD BE
CARRIED OUT WITH GREAT CARE.
The filament leads of magnetron carry High
Voltage with respect to ground. Extreme caution
must be exercised. Never plug the unit into a
power source to determine which component is
defective in high voltage section.
B. TO AVOID POSSIBLE EXPOSURE TO
MICROWAVE ENERGY LEAKAGE, THE
FOLLOWING PRECAUTIONS MUST BE TAKEN
BEFORE SERVICING.
(1) Before the power is applied:
(a) Make sure the primary interlock switch, the
secondary interlock switch and the interlock
monitor switch operate properly by opening
and closing the door several by opening and
closing the door several times.
(b) Make sure the perforated screen and the
dielectric choke of the door are correctly and
firmly mounted.
(4) The following items should be checked after the
unit is repaired:
(a) The interlock monitor switch is connected
correctly and firmly.
(b) The magnetron gasket is properly positioned
and mounted.
(c) The waveguide and the oven cavity are intact.
(no microwave energy leakage)
(d) The door can be properly closed and the
safety switches work properly.
(e) The unit must stop when the door is opened or
the time is up.
(2) After power is applied:
(a) Make sure the interlock switch mechanism
is operating properly by opening and closing
the door.
(b) Check microwave energy leakage must bebelow
the limit of 5 mW/cm2.
The unit must not be operated with any of the above
components removed or by-passed.
(All service adjustments should be made for
minimum microwave energy leakage
readings).
7-1
MICROWAVE LEAKAGE TEST
MEASURING MICROWAVE ENERGY
LEAKAGE
CAUTIONS
• Be sure to check microwave leakage prior to
servicing the oven if the oven is operative prior to
servicing.
• The service personnel should inform the
manufacture importer, or assembler of any certified
oven unit found to have a microwave emission level
in excess of 5 mW/cm2 and should repair any unit
found to have excessive emission levels, at no cost to
the owner, and should ascertain the cause of the
excessive leakage. The service personnel should
instruct the owner not to use the unit until the oven has
been brought into compliance.
• If the oven operates with the door open, the service
personnel should:
- Tell the user not to operate the oven.
• The service personnel should check all surface and
vent openings for microwave leakage.
• Check for microwave leakage after every servicing. The
power density of the microwave radiation leakage
emitted by the microwave oven should not exceed
4 mW/cm2. Always start measuring of an unknown field
to assure safety for operating personnel from radiation
leakage.
• Pour 275±15cc of 20±5°C(68±9°F) water in a beaker
which is graduated to 600 cc, and place the beaker
on the center of the turntable.
• Set the energy leakage monitor to 2,450 MHz and
use it following the manufacturer's recommended
test procedure to assure correct result.
• When measuring the leakage, always use the 2-inch
(5cm) spacer supplied with the probe.
• Operate the oven at its maximum output.
• Measure the microwave radiation using an
electromagnetic radiation monitor by holding the
probe perpendicular to the surface being measured.
Move probe along shaded area.
Probe scanning speed
Less than 2.5 cm/sec. ( 1 in/sec)
EQUIPMENT
• TESTER (VOLTS-DC, AC, Ohmmeter)
• Microwave survey meter
- Holaday HI-1500
HI-1501
- Narda 8100
8200
• 600 cc non conductive material beaker (glass or
plastic), inside diameter: approx. 8.5 cm (31/2 in.)
• Glass thermometer: 100°C or 212°F (1 deg scale)
7-2
MEASUREMENT WITH THE OUTER CASE
REMOVED
NOTE WHEN MEASURING
(1) Do not exceed meter full scale deflection.
(2) The test probe must be moved no faster than
1 inch/sec (2.5cm/sec) along the shaded area,
otherwise a false reading may result.
(3) The test probe must be held by the grip portion of
the handle. A false reading may result if the
operator’s hand is between the handle and the
probe.
(4) When testing near a corner of the door, keep
the probe perpendicular to the surface being
tested. (Hold vertically when testing the top and
bottom, and horizontally along the side.)
(1) When you replace the magnetron, measure for
microwave energy leakage before the outer case
is installed and after all necessary components
are replaced or adjusted. Special care should be
taken in measuring the following parts.
- Around the magnetron
- The waveguide
WARNING: AVOID CONTACTING ANY HIGH
VOLTAGE PARTS.
MEASUREMENT WITH A FULLY
ASSEMBLED OVEN
RECORD KEEPING AND NOTIFICATION
AFTER MEASUREMENT
(1) After all components, including the outer
panels, are fully assembled, measure for
microwave energy leakage around the door
viewing window, the exhaust opening and air
inlet openings.
(2) Microwave energy leakage must not exceed the
values prescribed below.
NOTES:
Leakage with the outer panels removed less than
5 mW/cm2. Leakage for a fully assembled oven
(“Before the latch switch (primary) is interrupted”)
with the door in a slightly opened position - less
than 2 mW/cm2.
(1) After adjustment and repair of any microwave
energy interruption or microwave energy blocking
device, record the measured values for future
reference. Also enter the information on the
service invoice.
(2) Should the microwave energy leakage not be
more than 2 mW/cm2 after determining that all
parts are in good condition, functioning properly
and genuine replacement parts which are listed in
this manual have been used.
(3) At least once a year, have the electromagnetic
energy leakage monitor checked for calibration
by its manufacturer.
POWER OUTPUT MEASUREMENT
(1) Microwave power output measurement is made with
the microwave oven supplied at its rated voltage and
operated at its maximum microwave power setting
with a load of (1000±5) g of potable water.
(2) The water is contained in a cylindrical borosilicate
glass vessel having a maximum material thickness of
1/8” (3 mm) and an outside diameter of
approximately 7.6” (190mm).
(3) The oven and the empty vessel are at ambient
temperature prior to the start of the test.
(4) The initial temperature (T1) of the water is (10±2)°C
(50°F) It is measured immediately before the water is
added to the vessel. After addition of the water to the
vessel, the load is immediately placed on the center
of the turntable which is in the lowest position and the
microwave power switched on.
(5) The time T for the temperature of the water to rise by
a value ∆ T of (10±2)°K is measured, where T is the
time in seconds and ∆T is the temperature rise. The
initial and final water temperatures are selected so
that the maximum difference between the final water
temperature and the ambient temperature is 5°K.
(6) The microwave power output P in watts is
calculated from the following formula :
P=
4187 x (∆T)
T
is measured while the microwave generator is
operating at full power. Magnetron filament heat-up
time is not included. (about 3 sec)
(7) The water is stirred to equalize temperature
throughout the vessel, prior to measuring the final
water temperature.
(8) Stirring devices and measuring instruments are
selected in order to minimize addition or removal of
heat.
WATER LOAD
TURNTABLE
7-3
DISASSEMBLY INSTRUCTIONS
(4) Remove 3 screws securing the circuit board.
IMPORTANT NOTES:
UNIT MUST BE DISCONNECTED FROM ELECTRICAL OUTLET WHEN MAKING REPAIRS, REPLACEMENTS, ADJUSTMENTS AND CONTINUITY CHECKS. WAIT AT LEAST ONE MINUTE,
UNTIL THE HIGH VOLTAGE CAPACITOR IN THE
HIGH VOLTAGE POWER SUPPLY HAS FULLY
DISCHARGED.
THE CAPACITOR SHOULD BE DISCHARGED BY
USING INSULATED WIRE - I.E. TEST PROBE
CONNECTED TO 10K-OHM RESISTOR IN SERIES
TO GROUND.
WHEN RECONNECTING THE WIRE LEADS TO
ANY PART, MAKE SURE THE WIRING CONNECTIONS AND LEAD COLORS ARE CORRECTLY
MATCHED ACCORDING TO THE OVERALL CIRCUIT DIAGRAM. (ESPECIALLY SWITCHES AND
HIGH VOLTAGE CIRCUIT.)
Circuit Board
A. REMOVING POWER AND CONTROL
CIRCUIT BOARD (Figures 1, 2 and 3)
Figure 2
(1) Remove a screw securing the control panel
assembly to the oven cavity.
(2) Remove the control panel with pushing it upward.
(3) Remove the connector (CN1) and wire leads
(Relay6) from the circuit board.
(5) Remove the FPC connector from the terminal
socket following “HOW TO REMOVE THE FPC
CONNECTOR” on the next page.
(6) Remove the circuit board from the control bracket
carefully.
Control Panel
Screw
Control Bracket
FPC Connector(S1)
Power Transformer
Relay 7
Circuit Board
(Relay 7)
(CN1)
Figure 1
Figure 3
7-4
HOW TO REMOVE THE F.P.C. CONNECTOR
HOW TO INSERT THE F.P.C. CONNECTOR
Follow the steps below as illustrated in Figures 4
and 5 to remove the F.P.C. connector.
Follow the steps below as illustrated in Figures 6
and 7 to insert the F.P.C. connector.
(1) Insert the F.P.C. connector into the terminal
socket securely with the fingers.
(2) Hold the plastic fastener with thumb and
forefinger of the other hand, and push it
slowly into the terminal socket. (Figure 6)
NOTE: When reconnecting the F.P.C
connector make sure that the holes
on the F.P.C. connector are properly
engaged with the hooks on the plastic
fastener
(3) Lock the level of the plastic fastener into the
hook of the terminal socket securely by
releasing the fingers.
(Figure 7)
(1) Hold the edges of the plastic fastener with
thumb and forefinger.
(Figure 4)
(2) Lift up the lever of the plastic fastener from
the terminal socket by lightly pressing the
lever end with forefinger.
(Figure 5)
(3) Remove the F.P.C. connector from the
terminal socket.
Plastic fastener
Plastic fastener
Hook
Holes
F.P.C.
Connector
Terminal
socket
F.P.C.
Connector
Figure 4
Terminal
socket
Figure 6
Plastic fastener
Hook
Plastic
fastener
Holes
F.P.C.
Connector
F.P.C.
Connector
Terminal
socket
Figure 5
Terminal
socket
Figure 7
7-5
B. REMOVING THE OUT CASE(Figure 8)
(6) Remove the power cord cover from outcase by
removing a screw.
(7) Remove the power cord to the inner of the out c
ase with turning power cord and remove the out
case with pushing it back.
(1) Remove the vent grille by removing two screws
securing it to the out case.
(2) Remove two screws securing it to the front bracket.
(3) Remove two screws securing it to the air duct.
(4) Remove the mounting plate by turning the two
screws securing it to the out case.
(5) Remove the base plate by removing six screws
securing it to the out case. Remove the Mount, All
from the out case by removing two screws securing
it to the out case and one screw securing it to the
ventilation motor ASS'Y and cavity.
Mount, All
Power code
Door
Mounting
Plate
Out Case
Vent Grille
Controller
Figure 8
7-6
C REMOVING THE DOOR INTERLOCK
SWITCHES (Figures 9,10)
(1) Disconnect the wire leads from the interlock
switches.
(2) Remove two screws securing the Latch Board.
(3) Make necessary replacements and check
microwave energy leakage according to
“ADJUSTMENT PROCEDURE” on page 7-12.
Latch Board
Secondary
Interlock Switch
Latch Board
Secondary Interlock Switch
WH(from H.V.Transformer)
WH(from Monitor S/W)
WH(from Oven Thermostat)
WH(from Cooktop lamp
Interlock
Monitor Switch
Primary
Interlock Switch
Monitor Interlock Switch
WH(from Secondary switch)
Figure 10
RD(from Ry 7)
Primary Interlock Switch
WIRE COLOR
SYMBOL
WH
BK
BR
RD
BL
PK
GY
GN(from P.C.B)
YL(from P.C.B)
Figure 9
7-7
COLOR
WHITE
BLACK
BROWN
RED
BLUE
PINK
GREY
GN
GREEN
N.P.
Not Provided
NOTES:
• When removing the magnetron, make sure that its
dome does not hit any adjacent parts, or it may be
damaged.
D. REMOVING MAGNETRON
(Figures 11 Through 13)
(1) Remove vertgrille.
(2) Remove mount all.
(3) Remove outcase.
(4) Discinnect the wireleads.
(5) Remove the 3 screws and Magnetron very
carefully.
• When replacing the magnetron, be sure to install the
magnetron gasket in the correct position and be sure
that the gasket is in good condition.
• After replacing the magnetron, check for microwave
energy leakage with a survey meter Check
microwave energy leakage must be below the limit of
5 mW/cm2. (All service adjustments should be made
for minimum microwave energy leakage readings.)
mount all
outcase
vertgrille
Figure 11
Magnetron
Figure 13
7-8
Figure 12
E. REMOVING DOOR (Figure 14)
(1) Remove the vent grille by two screws securing it to
the outcase loosening.
(2) Lift up and draw the door.
NOTES:
• After replacing the door, be sure to check that the
primary interlock switch, the secondary interlock
switch and the interlock monitor switch is in good
operating normally.
• After replacing the door, check for microwave energy
leakage with a survey meter. Microwave energy
leakage must be below the limit of 5mW/cm2. (With a
275 ml water load)
Figure 14
F. DISASSEMBLING DOOR (Figure 15)
(1) Remove the dielectric choke by using knife
blade or small screw driver, etc.
(2) Remove two screws securing it to the door handle.
CAUTION: Be careful not to damage door seal
plate with the screwdriver.
Door Screen
Figure 15
7-9
G. ASSEMBLING DOOR
(3) Carefully pull the ventilation motor ASS'Y out of the
microwave oven. (See Figure18)
(1) When mounting the door assembly to the oven
assembly, be sure to adjust the door assembly
parallel to the chassis. Also adjust so the door has no
play between the inner door surface and oven frame
assembly. If the door assembly is not mounted
properly, microwaves may leak from the clearance
between the door and the oven.
Space
Figure 18
H. REMOVING THE VENTILATION FAN
ASS’Y
(1) Remove the mounting plate by removing two
screws securing it to the back plate.
(See Figure 16)
(2) Remove the two screws securing the MOUNT, ALL
and one screw securing the ventilation fan ASS'Y.
(See Figure 17)
Figure 16
MOUNT, ALL
Figure 17
7-10
I. REMOVING THE TURNTABLE MOTOR
(1) Remove the turntable.
(2) Remove the turntable shaft VERY CAREFULLY
with a slotted screwdriver. (Figure 19)
(3) Remove the base plate by removing 6 screws
securing it to the oven cavity. (Figure 20)
(4) Disconnect the leadwire from the turntable motor
terminals.
(5) Remove the 2 screws securing the turntable motor
to the oven cavity ASS'Y. (Figure 21)
NOTES:
• Remove the leadwire from the turntable motor VERY
CAREFULLY.
• Be sure to grasp the connector not the wires when
removing.
Figure 19
Figure 20
Wire Leads
Turntable Motor
Figure 21
7-11
INTERLOCK SYSTEM
INTERLOCK MECHANISM
The door lock mechanism is a device which has been specially designed to eliminate completely microwave
activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave
leakage.
ADJUSTMENT PROCEDURES
To avoid possible exposure to microwave energy
leakage, adjust the door latches and interlock
switches, using the following procedure.
CHECK THE DOOR LATCH AND SWITCH
CLOSING.
NOTE:
The outer cover of the microwave oven is
removed.
The Interlock Monitor and Primary Interlock Switch act
as the final safety switch protecting the user from
microwave energy. The terminals between “COM” and
“NC” of the Interlock Monitor must close when the door
is opened. After adjusting the Interlock Monitor Switch,
make sure that it is correctly connected.
Mounting of the primary/monitor/secondary switches to
the latch board.
(1) Set the microwave oven on its side so that you can
see the latch board and the switches, as shown in
Figure 22.
(2) Close the door tightly and check gaps A and B to
be sure they are no more than 1/64” (0.5 mm).
See Figure 23 for close-up view of gaps A and B
(door latches). If all gaps are less than 1/64”
(0.5 mm), adjustment of the latch board may not
be necessary. Go to Steps 5 and 6 to check the
sequence of the switches.
Latch Board
NOTE:
To correct sequence of the Primary Interlock
Switch, Secondary Interlock Switch and the
Interlock Monitor Switch is very important.
If any gap is larger than 1/64” (0.5 mm), you will
need to adjust the latch board”. Go to step 3
and follow all steps in order.
Secondary
Interlock Switch
ADJUST THE LATCH AND SWITCH CLOSING
Interlock
Monitor Switch
(3) Loosen the two screws holding the plastic latch
board as shown.
Primary
Interlock Switch
(4) With the oven door closed tightly, move the latch
board upward toward the top of the oven and/or
away from the door latch until the gaps are less
than 1/64” (0.5 mm).
Hold the latch board tightly in this position until you
check the sequence of the switches in steps 5
and 6.
Figure 22
LATCH
0-1/64"
Figure 23
LATCH BOARD
0-1/64"
7-12
TEST THE LATCH AND SWITCH SEQUENCE
(5) Open the oven door slowly. Watch the door latch,
the Secondary Switch. Release Rod and Lever
on the switches to make sure they are zero to the
body of the switches in the following sequence:
(7) When you achieve the proper sequence of
switches in Steps 5 and 6, tighten the latch board
screws at that point.
TEST THE MICROWAVE ENERGY LEAKAGE
- Primary Interlock Switch
- Secondary Interlock Switch
- Interlock Monitor Switch
Make sure the microwave energy leakage is below the
limit of 1mW/cm2 (with a 275 ml water load) and
5mW/cm2 (with a 275 ml water load without the
cabinet) when measured with a survey meter.
Adjust the latch board until the switches operate in
this sequence. See Steps 3 and 4.
(6) Close the oven door slowly and be sure it is tightly
closed. Watch the three switches to make sure
they are zero to the body of the switches in the
following sequence:
- Interlock Monitor Switch
- Primary Interlock Switch
- Secondary Interlock Switch
NOTE: The Interlock Monitor Switch is an added
safety check on the Primary and
Secondary Interlock Switches. If the
Primary and Secondary Interlock Switches
allow the oven to operate with the door
open, the Monitor Switch will blow the
fuse.
7-13
INTERLOCK CONTINUITY TEST
A. PRIMARY INTERLOCK SWITCH TEST
B. SECONDARY INTERLOCK SWITCH TEST
Disconnect the wire lead from the secondary
switch.
Connect the ohmmeter leads to the common
(COM) and normally open (NO) terminals of the
switch. The meter should indicate an open circuit
in the door open condition. When the door is
closed, the meter should indicate a closed circuit.
When the secondary switch operation is abnormal,
make the necessary adjustment or replace the
switch only with the same type of switch.
When the door is opened slowly, an audible click
should be heard at the same time or successively
at intervals and the latches should activate the
switches with an audible click.
If the latches do not activate the switches when the
door is closed, the switches should be adjusted in
accordance with the adjustment procedure.
Disconnect the wire lead from the primary switch.
Connect the ohmmeter leads to the common
(COM) and normally open (NO) terminal of the
switch. The meter should indicate an open circuit
in the door open condition.
When the door is closed, the meter should indicate
a closed circuit.
When the primary switch operation is abnormal,
make the necessary adjustment or replace the
switch with the same type of switch.
COMPONENTS
SWITCHES
(Wire leads removed)
C. MONITOR SWITCH TEST
Disconnect the wire lead from the monitor switch.
Connect the ohmmeter leads to the common
(COM) and normally closed (NC) terminals of the
switch. The meter should indicate a closed circuit
in the door open condition. When the door is
closed, the meter should indicate an open circuit.
When the monitor switch operation is abnormal,
replace with the same type of switch.
NOTE: After repairing the door or the interlock
system, it is necessary to do this continuity
test before operating the oven.
TEST PROCEDURE
Check for continuity of the
switch with an Ohm-meter
Primary
Switch
Monitor
Switch
Secondary
Switch
RESULTS
Door
open
Door
closed
NO
COM
NC
COM
NO
COM
NOTE : After checking for the continuity of switches, make sure that they are
connected correctly.
WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION
EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.
TYPE NO. SZM-V16-FA-63 OR VP-533A-OF OR V-5230Q FOR PRIMARY SWITCH
TYPE NO. SZM-V16-FA-62 OR VP-532A-OF OR V-5220Q FOR MONITOR SWITCH
TYPE NO. SZM-V16-FA-63 OR VP-533A-OF OR V-5230Q FOR SECONDARY SWITCH
7-14
TEST AND CHECKOUT PROCEDURES, AND TROUBLE SHOOTING
- CAUTIONS - DISCONNECT THE POWER SUPPLY CORD
FROM THE WALL OUTLET WHENEVER
REMOVINGING THE CABINET FROM THE UNIT.
PROCEED WITH THE TESTS ONLY AFTER
DISCHARGING THE HIGH VOLTAGE CAPACITOR
AND REMOVING THE WIRE LEADS FROM THE
PRIMARY WINDING OF THE HIGH VOLTAGE
TRANSFORMER. (SEE FIGURE 24)
Filament
Winding
Secondary
Winding
- ALL OPERATIONAL CHECKS WITH MICROWAVE
ENERGY MUST BE DONE WITH A LOAD (1 LITER
OF WATER IN CONTAINER) IN THE OVEN.
Primary
Winding
Figure 24
A. TEST PROCEDURES
COMPONENTS
TEST PROCEDURES
1) Measure the resistance: Across the
filament terminals of the magnetron
with an ohm-meter on Rx1 scale.
MAGNETRON
(Wire leads are
removed)
HIGH-VOLTAGE
TRANSFORMER
(Wire leads are
removed)
2) Measure the resistance: Between
each filament terminal of the
magnetron and the chassis ground
with an ohm-mater on high test scale.
RESULTS
Normal reading:
Less than 1 ohm.
Normal reading:
Infinite ohms.
NOTE: Replace the magnetron, if the
magnetron checks and all of the
high voltage component tests are
good, but the unit still does not heat
a load.
1) Measure the resistance:
With an ohm-meter on Rx1 scale.
a. Primary winding;
b. Filament winding;
c. Secondary winding;
Normal readings:
Approx. 0.3 to 0.5 ohm.
Less than 0.1 ohm.
Approx. 65 to 120 ohms.
2) Measure the resistance:
With an ohm-meter on highest scale.
a. Primary winding to ground;
b. Filament winding to ground;
Normal readings:
Infinite ohms.
Infinite ohms.
NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.
7-15
COMPONENTS
TEST PROCEDURES
Measure the resistance:
(1) Terminal to terminal
Normal reading:
Momentarily indicates several ohms,
and then gradually returns to infinite
ohms.
Abnormal reading:
Indicates continuity or infinite ohms
from the beginning.
Ohmmeter
HIGH-VOLTAGE
CAPACITOR
RESULTS
Figure 25-a
Normal readings:
Infinite.
(2) Terminal to case
Abnormal reading:
Indicates continuity.
Ohmmeter
Figure 25-b
Normal readings:
continuity.
Measure the continuity:
(1) Forward
Abnormal reading:
Infinite.
Ohmmeter
HIGH-VOLTAGE
DIODE
Figure 26-a
Normal readings:
Infinite.
(1) Reverse
Abnormal reading:
continuity.
Ohmmeter
Figure 26-b
7-16
COMPONENTS
TEST PROCEDURES
Measure the resistance between terminal
pins of connector KEY CONNECTOR.
NOTE:
When reconnecting the FPC connector,
make sure that the holes on the FPC
connector are properly engaged with hooks
on the plastic fastener.
MATRIX CIRCUIT FOR
TOUCH KEY BOARD
TOUCH KEY
BOARD
RESULTS
Resistance
value
When
touched
Less than More than
400 ohms 1 mega ohm
FPC CONNECTOR
Top
1
2
3
4
5
6
7
8
9
10
11
12
13
CONNECTOR(KEY CON)
(For detail matrix circuit of each model,
refer to page 5-2.)
AUTO
COOK
TIME
COOK
CUSTOM
SET
AUTO
REHEAT
AUTO
DEFROST
CLOCK
Ez On
KITCHEN
TIMER
N.C
TIME
DEFROST
POWER
LEVEL
STOP/
CLEAR
N.C
Figure 27
7-17
When not
touched
Figure 28
COMPONENTS
TEST PROCEDURES
Check for continuity of relay 2 with an
ohm-meter.
(Remove wire leads from relay 2 and
operate the unit.)
Relay 2
RELAY2
Figure 29
CAUTION : The relay connector
2(White) and 5(Red) must be correctly
connected Relay 6.
These two connectors are not Interchangeable.
RESULTS
POWER
LEVEL
1
4 sec
18 sec
2
6 sec
16 sec
3
8 sec
14 sec
4
10 sec
12 sec
5
12 sec
10 sec
6
14 sec
8 sec
7
16 sec
6 sec
8
18 sec
4 sec
9
20 sec
2 sec
10
22 sec
0
NOTES:
• A MICROWAVE ENERGY TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR
ANY REASON.
• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.
• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE CONNECTOR, NOT
THE WIRES.
B. CHECKOUT PROCEDURES
(1) CHECKOUT PROCEDURES FOR FUSE BLOWING
CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.
PROBLEMS
CAUSES
Fuse blows immediately after
the door is closed.
Fuse blows immediately after
the door is opened.
Fuse blows when the door is closed and START
key is touched.
Improper operation of the primary interlock, secondary
interlock switches and/or the interlock monitor switch.
Malfunction of the high voltage transformer; the high
voltage capacitor including the diode, the magnetron,
the blower motor or the circuit board.
NOTES:
• If the fuse is blown by an improper switch operation, replace the all Interlock switches, PCB Ass’y and the fuse at
the same time. After replacing the the all Interlock switches, PCB Ass’y,Fuse with new ones, make sure that they
are correctly connected.
• Check for microwave energy leakage according to INTERLOCK ADJUSTMENT PROCEDURES on page 7-12
when the primary interlock, secondary interlock switches and/or the interlock monitor switches are adjusted or
replaced.
7-18
(2) CHECKOUT PROCEDURES FOR RELAY.
- PROBLEM (A) T.T. motor and oven lamp turn on without touching
START key when the door is closed.
NO
GOOD
YES
Remove the mate connector of I/O
CON from the circuit board.
Does the unit still operate?
NO
Replace the
circuit board
YES
Defective
RELAY3
Replace
RELAY3
- PROBLEM (B) T.T. motor and oven lamp turn on When the door is
closed and START key is touched.
NO
YES
GOOD
Measure the voltage at pin NO.
4 of U01
Voltage reading: 0 Vdc
NO
Replace the
circuit board
YES
Defective
RELAY3 or poor
connection of
RELAY3
Replace
RELAY3 or correct
the connection.
7-19
(3) CHECKOUT PROCEDURES FOR CIRCUIT
BOARD
The following symptoms indicate a defective circuit
board.
1) The start function fails to operate but the high
voltage Systems, the interlock switches, the door
sensing and the relay check good.
2) The unit with a normal relay continuously operates.
3) Proper temperature measurement is not obtained.
4) The buzzer does not sound or continues to sound.
5) Some segments of one or more digits do not light
up, or they continue to light up, or segments light
when they should not.
6)
7)
8)
9)
Wrong figures appear.
The figures of all digits.
Some of the indicators do no flicker light up.
The clock does not keep time properly.
NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.
7-20
7-21
Measure voltage between pin 1
and pin 3 of connector CN1.
WH
RD
1
Measure resistance of touch
key board after removing
connector S1.
(See page 7-4 and 7-17)
120
Resistance
incorrect
Normal
resistance
Voltage
incorrect
0
120
120V
0
Replace touch
key board.
Check contact
of connector S1
Correct
connections
Replace
circuit board
Check: 1. POWER SUPPLY
2. FUSE (See “CHECKOUT PROCEDURES FOR FUSE BLOWING: on page 7-18)
3. OVEN CAVITY THERMOSTAT
PROBLEM - B: Display does not show correct numbers and/or
correct indications when programmed.
1
PROBLEM - A: “PLEASE SET TIME OF DAY” does not appear in display window when power supply cord is
plugged into wall outlet.
C. TROUBLE SHOOTING
Before following this troubleshooting read “TRIAL OPERATION” on page 6-1.
• “DISPLAY” Problems, “A” thru “C”
• “HELP UP” Problems, “D” thru “E”
• “BUZZER Problems, “F”
Normal touch
key board
Poor
contact
Contact
ok
Normal
resistance
Normal
circuit board
Correct
seating
Replace
circuit board
Normal
contact
Normal
circuit board
Runs
Runs
Runs
Runs
Runs
7-22
Measure resistance of
H.V.Transformer
(see page 7-15)
2
Normal
resistance
Resistance
incorrect
Contact
OK
NO
continuity
Replace H.V.T.
Normal H.V.T.
Normal
circuit board
Check the continuity of
H.V.C. (see page 7-16)
Check contact of
connector S1
Replace
circuit board
Check: 1. PRIMARY AND SECONDARY INTERLOCK SWITCHES
2 . THERMOSTAT
Check the contact of
relay 6(see page 7-18)
1
PROBLEM - C: Unit does not heat up even if display counts down when
START key is touched for "HIGH POWER" cooking.
Normal
resistance
Resistance
incorrect
Contact OK
Poor contact
Check the
continuity of H.V.D.
(see page 7-16)
Replace
circuit board
Correct
seating
Normal
H.V.D.
Normal
Magnetron
Replace H.V.D.
Replace
Magnetron
Normal
Normal H.V.C.
Abnormal
Replace H.V.C.
Normal
circuit board
Normal
contact
Runs
Runs
Runs
7-23
1
Check normal
operation
circuit board
PROBLEM - D : No buzzing when touching the key, between
stages or at end of cooking
Replace
circuit board
Normal
circuit board
Runs
7-24
1
Check the contact of
oven thermostat
Check: 1. POWER SUPPLY
2. FUSE
Contact
OK
NO
contact
Check contact
of connector S1
(see page 7-4)
Replace
oven thermostat
PROBLEM - E : Ventilation fan does not operate when “FAN HIGH/LOW” key is touched.
Contact OK
Poor contact
Replace
circuit board
Correct
seating
Normal
circuit board
Normal
contact
NO runs
Replace
ventilation
motor ASS’Y
Normal
ventilation
motor ASS’Y
Runs
Runs
Runs
Runs
EXPLODED VIEW
DOOR
13581A
13552A
13536A
13213A
13720D
WTT028
14890A
14026A
14970A
13650A
8-1
CONTROL PANEL
268711
24781M
24810P
WTP018
23572A
WTT029
*07
23506A
8-2
OVEN CAVITY
WTT021
34960A
WTT028
WTT029
WTT029
33530A
34810Q
33112U
*01
*02
*05
*04
368771
535501
63302A
36912C
34890C
34810T
WTT022
35230A
8-3
WTT022
63303A
LATCH BOARD
43500A
466001
WSZ084
43501A
466003
466001
44510A
8-4
INTERIOR (I)
WSZ002
33390G
56324A
34370T
53300A
35889A
WTT021
WTT021
WSZ098
56170D
33740A
33052A
WTT021
WTT021
36549S
WTP013
WSZ002
53300B
56851D
WSZ002
54810C
50CZZH
8-5
INTERIOR (II)
56912B
55231C
53550L
36549V
56804A
WTT028
56411A
55262A
50FZZA
56930V
55006F
568771
WSZ002
8-6
INSTALLATION
44360A
WSZ098
WSZ133
WBZZ02
WWZ068
WWZ068
63300M
WBZZ01
65862D
WSZ136
65862B
63861A
8-7
SCHEMATIC DIAGRAM OF P.C.B
CLOCK
CUSTOM
SET
EZOn
N.C
N.C
N.C
KITCHEN
N.C
LEVEL
8-12
PRINTED CIRCUIT BOARD
8-13
P/NO : 3828W5S2380
July, 2002
Printed in Korea