Electrolux EW30MO55HSA Service manual

Technical Service Manual
Microwave Oven
Models
EW27MO55HSA
EW30MO55HSA
Publication #5995532487
P/N 316439272
April 2009
Basic Information
Safe Servicing Practices
Avoid personal injury and/or property damage by observing important Safe Servicing Practices.
Following are some limited examples of safe practices:
1. DO NOT attempt a product repair if you have any doubts as to your ability to complete the repair in a safe and
satisfactory manner.
2. Always Use The Correct Replacement Parts as indicated in the parts documentation. Substitutions may defeat
compliance with Safety Standards Set For Home Appliances. Do not exceed maximum recommended wattage on
light bulb replacements. Doing so could blow fuses and/or damage transformers.
3. Before servicing or moving an appliance:
• Remove power cord from the electrical outlet, trip circuit breaker to the OFF position, or remove fuse.
4. Never interfere with the proper operation of any safety device.
5. Use ONLY REPLACEMENT PARTS CATALOGED FOR THIS APPLIANCE. Substitutions may defeat compliance
with Safety Standards Set For Home Appliances.
6. GROUNDING: The standard color coding for safety ground wires is GREEN, or GREEN with YELLOW STRIPES.
Ground leads are not to be used as current carrying conductors. It is EXTREMELY important that the service
technician reestablish all safety grounds prior to completion of service. Failure to do so will create a hazard.
7. Prior to returning the product to service, ensure that:
• All electrical connections are correct and secure.
• All electrical leads are properly dressed and secured away from sharp edges, high-temperature components,
and moving parts.
• All non-insulated electrical terminals, connectors, heaters, etc. are adequately spaced away from all metal
parts and panels.
• All safety grounds (both internal and external) are correctly and securely connected.
• All panels are properly and securely reassembled.
© 2008 Electrolux Home Products, Inc.
1-1
Basic Information
This Manual has been prepared to provide Electrolux Service Personnel with Operation and
Service Information for Electrolux Microwave Ovens EW27MO55HSA and EW30MO55HSA.
Table of Contents
Section 1 Basic Information
Section 4 Component Teardown
Safe Servicing Practices.......................................... 1-1
Table of Contents .................................................... 1-2
Warnings and Safety Information ............................ 1-3
Precautions To Be Observed Before And During
Servicing To Avoid Possible Exposure To
Excessive Microwave Energy .................................. 1-4
Before Servicing ...................................................... 1-4
Danger High Voltage ............................................... 1-4
Before Servicing ...................................................... 1-5
Microwave Measurement Procedure USA .............. 1-6
Microwave Measurement Procedure Canada ......... 1-7
Product Specification ............................................... 1-8
Grounding Instructions ............................................ 1-9
Oven Diagram ......................................................... 1-10
Warnings and Cautions ...........................................
Outer Case Removal ...............................................
Magnetron Removal ................................................
Power Transformer Removal...................................
High Voltage Rectifier Removal...............................
High Voltage Capacitor Removal ............................
Turntable Motor/Coupling Removal .........................
Oven Lamp and Lamp Socket Removal ..................
Fan Motor Removal .................................................
Power Supply Cord Replacement ...........................
Door Sensing Switch, Primary/Third Interlock
Switch and Monitor Switch Replacement ................
Door Replacement...................................................
Door Adjustment ......................................................
Door Disassembly ...................................................
Control Assembly And CPU Unit Removal ..............
Section 2 Operation
Operating Sequence Description.............................
Oven Schematic-Off Condition ................................
Oven Schematic-Cooking Condition........................
Variable Cooking .....................................................
Sensor Cooking Condition .......................................
Cooking Sequence ..................................................
Auto Defrost Cooking ..............................................
Component Descriptions .........................................
Door Sensing and Primary Interlock Switch ............
Monitor Switch .........................................................
Third Door Switch ....................................................
Magnetron Thermal Switch Cut-Out ........................
Oven Thermal Cut-Out ............................................
Humidity Sensor Circuit ...........................................
2-1
2-2
2-2
2-3
2-3
2-3
2-4
2-4
2-4
2-4
2-4
2-5
2-5
2-5
4-5
4-7
4-8
4-8
4-9
Section 5 Wire Diagrams
Wiring Schematic Oven Off Condition .....................
Pictorial Diagram .....................................................
5-1
5-2
Section 6 Parts List
Parts Listing .............................................................
Oven And Cabinet Parts Exploded View .................
Cabinet And Frame Parts Exploded View ...............
Control And Door Parts Exploded View...................
Packing and Accessories Exploded View................
Section 3 Troubleshooting and Testing
Warnings and Cautions ...........................................
Troubleshooting Guide Chart ..................................
Test Procedures ......................................................
4-1
4-2
4-2
4-2
4-3
4-3
4-3
4-3
4-4
4-5
3-1
3-2
3-3
1-2
6-1
6-3
6-4
6-5
6-6
Basic Information
CERTAIN INITIAL PARTS ARE INTENTIONALLY NOT GROUNDED AND PRESENT A RISK OF ELECTRICAL
SHOCK ONLY DURING SERVICING. SERVICE PERSONNEL - DO NOT CONTACT THE FOLLOWING PARTS
WHILE THE APPLIANCE IS ENERGIZED:
INVERTER UNIT, THAT INCLUDES HIGH VOLTAGE CAPACITOR, HIGH VOLTAGE POWER TRANSFORMER,
HIGH VOLTAGE RECTIFIER, HEAT SINK, ETC., AND MAGNETRON, HIGH VOLTAGE HARNESS ETC.;
IF PROVIDED, FAN ASSEMBLY, COOLING FAN MOTOR.
ALL THE PARTS MARKED “*” ON PARTS LIST ARE USED AT VOLTAGES MORE THAN 250V.
REMOVAL OF THE OUTER WRAPPER GIVES ACCESS TO VOLTAGE ABOVE 250V.
ALL THE PARTS MARKED “Ä” ON PARTS LIST MAY CAUSE UNDUE MICROWAVE EXPOSURE, BY
THEMSELVES, OR WHEN THEY ARE DAMAGED, LOOSENED OR REMOVED.
THIS SERVICE MANUAL IS INTENDED FOR USE BY PERSONS HAVING ELECTRICAL AND MECHANICAL
TRAINING AND A LEVEL OF KNOWLEDGE OF THESE SUBJECTS GENERALLY CONSIDERED
ACCEPTABLE IN THE APPLIANCE REPAIR TRADE. ELECTROLUX HOME PRODUCTS CANNOT BE
RESPONSIBLE, NOR ASSUME ANY LIABILITY, FOR INJURY OR DAMAGE OF ANY KIND ARISING FROM
THE USE OF THIS MANUAL.
NEVER OPERATE THE OVEN UNTIL THE FOLLOWING POINTS ARE ENSURED.
(A) THE DOOR IS TIGHTLY CLOSED.
(B) THE DOOR BRACKETS AND HINGES ARE NOT DEFECTIVE.
(C) THE DOOR PACKING IS NOT DAMAGED.
(D) THE DOOR IS NOT DEFORMED OR WARPED.
(E) THERE IS NO OTHER VISIBLE DAMAGE WITH THE OVEN.
SERVICING AND REPAIR WORK MUST BE CARRIED OUT ONLY BY TRAINED SERVICE PERSONNEL.
1-3
Basic Information
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 Federal Performance Standard should be performed on
each oven prior to release to the owner.
Before Servicing
Before servicing an operative unit, perform a microwave emission check as per the Microwave Measurement
Procedure outlined in this service manual.
If microwave emissions level is in excess of the specified limit, contact ELECTROLUX HOME PRODUCTS, INC.
immediately.
If the unit operates with the door open, service person should:
1) Tell the user not to operate the oven.
2) Contact Electrolux HOME PRODUCTS, INC. and Food and Drug Administration’s Center for Devices and
Radiological Health immediately.
Service personnel should inform ELECTROLUX HOME PRODUCTS, INC. of any certified unit found with emissions
in excess of 4mW/cm2. The owner of the unit should be instructed not to use the unit until the oven has been brought
into compliance.
DANGER HIGH VOLTAGE
Do not energize a microwave oven with the outer case cabinet removed, because a microwave oven generates high
voltage in the circuit.
If you intend to operate the oven employing the high frequency switching power converter circuit, you should take
special precautions to avoid an electrical shock hazard.
The high voltage transformer, high voltage capacitor and high voltage diode have energized high voltage potential
of approximately 8KV.
The aluminium heat sink is connected to the switching power transistor collector pole, and has an energized high
voltage potential of approximately 650V peak.
DO NOT ACCESS THE HIGH VOLTAGE TRANSFORMER, HIGH VOLTAGE CAPACITOR, HIGH VOLTAGE
DIODE AND HEAT SINK WHEN THE POWER SUPPLY IS CONNECTED TO AN ELECTRICAL OUTLET.
1-4
Basic Information
MICROWAVE OVENS CONTAIN CIRCUITRY CAPABLE OF PRODUCING
VERY HIGH VOLTAGE AND CURRENT. CONTACT WITH THE
FOLLOWING PARTS MAY RESULT IN A SEVERE, POSSIBLY FATAL,
ELECTRICAL SHOCK.
INVERTER UNIT, THAT INCLUDES HIGH VOLTAGE CAPACITOR,
HIGH VOLTAGE POWER TRANSFORMER, HIGH VOLTAGE RECTIFIER,
HEAT SINK ETC., AND MAGNETRON, HIGH VOLTAGE HARNESS ETC..
READ THE SERVICE MANUAL CAREFULLY AND FOLLOW ALL
INSTRUCTIONS.
Don't Touch !
Danger High Voltage
Before Servicing
When Testing Is Completed
1. Disconnect the power supply cord, and then remove
outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
1.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of the
high-voltage capacitor (that is the connecting lead of the
high-voltage rectifier) against the chassis with the use
of an insulated screwdriver.
Whenever troubleshooting is performed, the power
supply must be disconnected. It may, in some cases, be
necessary to connect the power supply after the outer
case has been removed, in this event:
1. Disconnect the oven power supply cord and then
remove the outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect leads to the primary of the inverter unit.
5. Ensure that these leads remain isolated from other
components and oven chassis by using insulation
tape.
6. After that procedure, reconnect the power supply
cord.
2.
3.
Disconnect the power supply cord, and then remove
outer case.
Open the door and block it open.
Discharge high voltage capacitor.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of the
high-voltage capacitor (that is the connecting lead of the
high-voltage rectifier) against the chassis with the use
of an insulated screwdriver.
4.
5.
6.
7.
Reconnect leads to the primary of the inverter unit.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer
case is installed.
Run the oven and check all functions.
After repairing
1. Reconnect all leads removed from components
during testing.
2. Reinstall the outer case (cabinet).
3. Reconnect the power supply cord after the outer
case is installed.
4. Run the oven and check all functions.
Microwave ovens should not be run empty. To test
for the presence of microwave energy within a cavity,
place a cup of cold water on the oven turntable, close
the door and set the power to HIGH and then set the
microwave timer for two (2) minutes. When the two
minutes has elapsed (timer at zero) carefully check
that the water is now hot. If the water remains cold
carry out Before Servicing procedure and re-examine
the connections to the component being tested.
1-5
Basic Information
Microwave Measurement Procedure (USA)
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a
microwave oven should not exceed 1 mW/cm2 at any point 5 cm or more from the external surface of the
oven, measured prior to acquisition by a purchaser, and thereafter (through the useful life of the oven),
5 mW/cm2 at any point 5 cm or more from the external surface of the oven.
2) Safety interlock switches: Primary interlock switch shall prevent microwave radiation emission in excess of the
requirement as above mentioned, secondary interlock switch shall prevent microwave radiation emission in
excess of 5 mW/cm2 at any point 5 cm or more from the external surface of the oven.
B. Preparation for testing:
Before beginning the actual measurement of leakage, proceed as follows:
1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.
Important:
Survey instruments that comply with the requirement for instrumentation as prescribed by the performance
standard for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.
2) Place the oven tray in the oven cavity.
3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20°±5C (68°F) in the center of the oven cavity.
The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm
(3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic. The placing of this
standard load in the oven is important not only to protect the oven, but also to insure that any leakage is
measured accurately.
4) Set the cooking control on Full Power Cooking Mode.
5) Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is
completed, replace it with 275 ml of cool water.
C. Leakage test:
Closed-door leakage test (microwave measurement)
1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and
the body of the oven.
2) Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the maximum
indication on the meter.
3) Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity
of the metal has been breached (eg., around the switches, indicator, and vents). While testing for leakage
around the door pull the door away from the front of the oven as far as is permitted by the closed latch
assembly.
4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than
4 mW/cm2, and that the primary interlock switch and secondary interlock switch do turn the oven OFF before
any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
1-6
Basic Information
Microwave Measurement Procedure (Canada)
After adjustment of the door switches are completed individually or collectively, switch test and microwave leakage
test must be performed with survey instrument and test result must be confirmed to meet the requirement of the
performance standard for microwave ovens as under mentioned.
A. Requirements:
Every microwave oven shall function in such a manner that when the oven is fully assembled and operating with
its service controls and user controls adjusted to yield the maximum output, the leakage radiation, at all points at
least 5 cm. from the external surface of the oven, does not exceed:
1) 1.0 mW/cm2 with the test load of 275 ± 15 ml of water at an initial temperature 20 ±5°C.
2) 5.0 mW/cm2 when the outer enclosure is removed with a test load of 275 ± 15 ml of water at an initial
temperature 20±5°C.
3) 5.0 mW/cm2 without a test load.
B. Preparation for testing:
Before beginning the actual measurement of leakage, proceed as follows:
1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.
Survey instruments that comply with the requirement for instrumentation as prescribed by CSA and NHW
performance standard for microwave ovens must be used for testing recommended instruments are, NARDA
8100 and NARDA 8200.
2) Place the oven tray in the oven cavity.
3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20°±5C (68°F) in the center of oven cavity. The
water container shall be a low form of a 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm
(3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic. The placing of this
standard load in the oven is important not only to protect the oven, but also to insure that any leakage
is measured accurately.
4) Set the cooking control on Full Power Cooking Mode
5) Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is
completed, replace it with 275 ml of cool water.
C. Leakage test with enclosure installed:
1) Grasp probe of survey instrument and hold it perpendicular to gap between door and the body of the oven.
2) Move the probe slowly, not faster than 2.5 cm/sec. along the gap, watching for maximum indication on meter.
3) Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity
of the metal has been breached (eg., around the switches, indicator, and vents). While testing for leakage
around door, pull door away from the front of the oven as far as is permitted by the closed latch assembly.
4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater
than 4 mW/cm2, and that the primary interlock switch and secondary interlock switch do turn the oven
OFF before any door movement.
D. Leakage test without enclosure:
1) Remove the enclosure (cabinet).
2) Grasp the probe of the survey instrument and hold it perpendicular to all mechanical and electric parts of the
oven that is accessible to the user of the oven including, but not limited to, the waveguide, cavity seams,
magnetron gap between the door and the body of the oven.
3) Move probe slowly, not faster than 2.5 cm/sec. along the gap, watching for the maximum indication on meter.
4) Measure carefully at the point of highest leakage and make sure that the highest leakage is under 5 mW/cm2.
CAUTION: Special attention should be given to avoid electrical shock because HIGH VOLTAGE is generated
during this test
E. No Load test
1) Operate the oven without a load and measure the leakage by the same method as the above test procedure
“ Leakage test with enclosure installed”
2) Make sure that the highest leakage should not exceed 5 mW/cm2.
NOTE: After servicing, record data on service invoice and microwave leakage report.
1-7
Basic Information
Product Specification
Item
Description
Power Requirements
(USA)120 Volts / 13.7 Amperes (Canada) 117 Volts / 13.0 Amperes
60 Hertz
Single phase, 3 wire grounded
Power Output
900 watts (IEC 705 Test Procedure)
Operating frequency of 2450MHz
Case Dimensions
27” Unit Dimensions (including handle)
30” Unit Dimensions (including handle)
Width 27”
Width 30”
Height 20-7/8”
Height 20-7/8”
Depth 24-7/32”
Depth 24-7/32”
Cooking Cavity Dimensions
(1.5 Cubic Feet )
Width 16-5/32”
Height 9-21/32”
Depth 16-5/32”
Oven Cavity Light
Yes
Hood fan
Approx. High - 300 C.F.M. / Low - 270 C.F.M.
Control Complement
Touch Control System
Clock ( 1:00 - 12:59 )
Timer (0 - 99 min. 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
P-HI Full power throughout the cooking time
P-90 approx. 90% of Full Power
P-80 approx. 80% of Full Power
P-70 approx. 70% of Full Power
P-60 approx. 60% of Full Power
P-50 approx. 50% of Full Power
P-40 approx. 40% of Full Power
P-30 approx. 30% of Full Power
P-20 approx. 20% of Full Power
P-10 approx. 10% of Full Power
P-0 No power throughout the cooking time
Auto Reheat pad, Add 30 sec pad, Popcorn pad
Auto Defrost pad, Sensor Cook pad, Fresh veggies pad, Frozen veggies
pad, Baked potato pad, Sensor reheat pad, User pref pad, Pizza slice pad,
Beverage pad, Melt/Soften pad, Snacks pad, Number selection pads,
Timer pad, Clock pad, Stop/Clear pad, Power Level pad,
Start / On-Off pad
Safety Standard
UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
Canadian Standards Association
Health CANADA, Industry Canada
1-8
Basic Information
Grounding Instructions
3-Pronged Plug
This oven is equipped with a three prong grounding plug.
It must be plugged into a wall receptacle that is properly
installed and grounded in accordance with the National
Electrical Code, local codes and ordinances. In the event
of an electrical short circuit, grounding reduces the risk of
electric shock by providing an escape wire for the electric
current.
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
IMPROPER USE OF THE GROUNDING PLUG CAN
RESULT IN A RISK OF ELECTRIC SHOCK.
Electrical Requirements
The oven is equipped with a 3-prong grounding plug.
DO NOT UNDER ANY CIRCUMSTANCES CUT OR
REMOVE THE GROUNDING PIN FROM THE PLUG.
The power supply cord and plug must be connected to a
separate 120 Volt AC, 60 Hz, 15 Amp. or more dedicated
line, using a grounded receptacle. When installing this
appliance, observe all applicable codes and ordinances.
A short power-supply cord is provided to reduce risks of
becoming entangled in or tripping over a longer cord.
Where a two-pronged wall-receptacle is encountered, it is
the personal responsibility and obligation of the customer
to contact a qualified electrician and have it replaced with
a properly grounded three-pronged wall receptacle or
have a grounding adapter properly grounded and
polarized.
If an extension cord must be used, it should be a 3-wire,
15 amp. or more cord. Do not drape over a countertop or
table where it can be pulled on by children or tripped over
accidentally.
1-9
Basic Information
Oven Diagram
1.
2.
3.
4.
5.
Control panel
Ventilation openings
Model / Serial label
Door seals and sealing surfaces
Safety door latches - The oven will not operate
unless the door is securely closed.
6. Oven door with see-through window
7. Door handle
8. Door hinges
9. Turntable motor shaft
10. Menu label
11. Oven light - It will light when oven is operating or
door is open.
12. Waveguide cover: DO NOT REMOVE.
13. Time display: 99 minutes, 99 seconds
14. Popcorn/Bacon Tray
15. Removable turntable - Place the turntable on the
turntable support securely. The turntable will rotate
clockwise or counterclockwise. Only remove for
cleaning.
16. Removable turntable support - Carefully place the
turntable support in the center of the oven floor.
OVEN DIAGRAM
13
12
14
1
2
3
4
5
11
10
9
15
8
16
7
6
TOUCH CONTROL PANEL
1-10
Operation
Operating Sequence Description
The following is a description of component functions
during oven operation.
OFF CONDITION
Closing the door activates the stop switch, primary
interlock switch and secondary interlock switch.
(In this condition, the monitor switch contacts are
opened.) When oven is plugged in, 117 volts AC is
supplied to the control unit. (Figure 2-1).
1. The display will show “Enjoy your oven, press clear
and press clock”. To set any program or set the
clock, you must first touch the STOP/CLEAR
button. The display will clear, and “ : “ appears.
NOTE: When door is opened, the oven lamp comes on.
COOKING CONDITION
Program desired cooking time touching the NUMBER
pads. When the START button is touched, the following
operations occur:
1. The contacts of relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure 2-2)
RELAY CONNECTED COMPONENTS
RY1
Oven lamp / Turntable motor
RY2
Power Transformer
RY3
Fan motor
6. When the door is opened during a cook cycle, third
door switch, monitor switch, door sensing switch, the
secondary interlock relay and the primary interlock
switch are activated with the following results. The
circuits to the turntable motor, the cooling fan motor,
and the high voltage components are de-energized,
the oven lamp remains on, and the digital read-out
displays the time still remaining in the cook cycle
when the door was opened.
7. The monitor switch is electrically monitoring the
operation of the secondary interlock switch and
primary interlock switch and is mechanically
associated with the door so that it will function in
the following sequence.
(1) When the door opens from a closed position,
the primary interlock switch and secondary interlock
switch open their contacts, and then the monitor
switch contacts close.
(2) When the door is closed from the open position,
the monitor switch contacts open first. Then the
contacts of the secondary interlock switch and
door sensing switch close.
If relay (RY1) and the primary interlock switch fail with
their contacts closed when the door is opened, the
closing of the monitor switch contacts will form a short
circuit through the monitor fuse, the relay (RY1) and
the primary interlock switch, causing the monitor fuse to
blow.
2. 117 volts AC is supplied to the primary winding of
the power transformer and is converted to about
3.0 volts AC output on the filament winding, and
approximately 2360 volts AC on the high voltage
winding.
3. The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a
voltage doubler circuit.
4. The microwave energy produced by the magnetron
is channeled through the waveguide into the cavity
feedbox, and then into the cavity where the food
is placed to be cooked.
5. Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generation of microwave energy is stopped. The
oven will revert to the OFF condition.
2-1
Operation
SCHEMATIC DIAGRAM
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
SCHEMATIC DIAGRAM (DOOR CLOSED,COOK OFF CONDITION)
NOISE FILTER UNIT
RY4
RY5
RY6
ORG
PRIMARY INTERLOCK SWITCH
RY1
POWER
TRANSFORMER
B10
CONTROL
UNIT
A1
SECONDARY
INTERLOCK
RELAY
RY3
RY2
MONITOR SWITCH
(RY2)
DM
(RY2)
(RY3)
E1
E2
E3
DOOR
SENSING
SWITCH
E4
E5
THERMISTOR
E6
DAMPER
SWITCH
F3 F2
F1
CAPACITOR
0.94
H.V.
RECTIFIER
HEATING
ELEMENT
FAN MOTOR
OVEN LAMP
1.
2.
(RY1)
A3
B8
3RD
DOOR
SWITCH
NOTE:
A5
A7
(RY1)
B1
B2
B3
B4
B5
B6
(RY3)
CONVECTION MOTOR
TURNTABLE MOTOR
0.0033 F AC125V
120V
60Hz
FM
OVEN
THERMAL
CUT-OUT
A9
L.V.
TRANSFORMER
CM
*
OL
BRN
PPL
PNK
RED・PNK
TTM
MAGNETRON
THERMAL
CUT-OUT
DAMPER MOTOR
NOISE SUPPRESSION COIL
0.22 F AC250V
0.0033 F AC125V
FUSE
20A
CONV.
THERMAL
CUT-OUT
AH SENSOR
MAGNETRON
CIRCUITS SUBJECT TO CHANGE WITHOUT NOTICE
WIRE COLOR CODES ARE APPLICABLE TO PRIMARY CIRCUIT ONLY AND NOT
APPLICABLE TO LOW VOLTAGE CIRCUIT AND SECONDARY CIRCUIT.
HOT WIRE(S) MUST BE CONNECTED TO THE TERMINAL WITH BLUE MARK
ON THE LAMP SOCKET AND "H" MARK ON THE POWER SUPPLY CORD.
*3.
Figure 2-1. Oven Off Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. COOKING TIME PROGRAMMED.
3. “START” PAD TOUCHED.
NOISE FILTER UNIT
3RD
DOOR
SWITCH
NOTE:
1.
2.
*3.
MAGNETRON
THERMAL
CUT-OUT
OVEN
THERMAL
CUT-OUT
A9
L.V.
TRANSFORMER
A5
A7
(RY1)
A3
(RY1)
B1
B2
B3
B4
B5
B6
RY4
RY5
RY6
PRIMARY INTERLOCK SWITCH
ORG
BRN
RY1
POWER
TRANSFORMER
(RY3)
B8
(RY2)
B10
CONTROL
UNIT
DAMPER MOTOR
A1
SECONDARY
INTERLOCK
RELAY
RY3
RY2
MONITOR SWITCH
DM
(RY2)
(RY3)
E1
E2
DOOR
SENSING
SWITCH
E3
E4
THERMISTOR
E5
E6
DAMPER
SWITCH
F3 F2
F1
AH SENSOR
CIRCUITS SUBJECT TO CHANGE WITHOUT NOTICE
WIRE COLOR CODES ARE APPLICABLE TO PRIMARY CIRCUIT ONLY AND NOT
APPLICABLE TO LOW VOLTAGE CIRCUIT AND SECONDARY CIRCUIT.
HOT WIRE(S) MUST BE CONNECTED TO THE TERMINAL WITH BLUE MARK
ON THE LAMP SOCKET AND "H" MARK ON THE POWER SUPPLY CORD.
Figure 2-2. Oven ON (Cooking) Condition
2-2
HEATING
ELEMENT
PPL
FM
FAN MOTOR
TURNTABLE MOTOR
OL
CONVECTION MOTOR
CM
*
OVEN LAMP
120V
60Hz
PNK
RED・PNK
0.0033 F AC125V
TTM
0.0033 F AC125V
0.22 F AC250V
NOISE SUPPRESSION COIL
FUSE
20A
CONV.
THERMAL
CUT-OUT
CAPACITOR
0.94
H.V.
RECTIFIER
MAGNETRON
Operation
2. Heat Potatoes. Moisture and humidity is emitted
rapidly. You can smell the aroma as it cooks.
Variable Cooking
When Variable Cooking Power is programmed, the
120 volts AC is supplied to the power transformer
intermittently through the contacts of relay (RY2) which is
operated by the control unit within an interval second time
base. Microwave power operation is as follows:
Vari-Mode
ON TIME
OFF TIME
Power 10 (High) (100% Power)
Power9(P-90) (Approx. 90%)
Power8(P-80) (Approx. 80%)
Power7(P-70) (Approx. 70%)
Power6(P-60) (Approx. 60%)
Power5(P-50) (Approx. 50%)
Power4(P-40) (Approx. 40%)
Power3(P-30) (Approx. 30%)
Power2(P-20) (Approx. 20%)
Power1(P-10) (Approx. 10%)
Power0(P-0) (0% power)
32 sec.
30 sec.
26 sec.
24 sec.
22 sec.
18 sec.
16 sec.
12 sec.
8 sec.
6 sec.
0 sec.
0 sec.
2 sec.
6 sec.
8 sec.
10 sec.
14 sec.
16 sec.
20 sec.
24 sec.
26 sec.
32 sec.
MIC
RO
WA
VE
3. Sensor detects moisture and humidity and
calculates cooking time and variable power.
AH SENSOR
MIC
RO
WA
VE
COOKING SEQUENCE
The ON/OFF time ratio does not correspond with the
percentage of microwave power, because approx. 2
seconds are needed for heating of the magnetron
filament.
1. Touch SENSOR COOK pad.
NOTE: The oven should not be operated on SENSOR
immediately after plugging in the unit. Wait two minutes
before cooking on SENSOR.
SENSOR COOKING CONDITION
Using the SENSOR COOK function, the foods are
cooked without figuring time, power level or quantity.
When the oven senses enough steam from the food, it
relays the information to its microprocessor which will
calculate the remaining cooking time and power level
needed for best results.
When food is cooked, water vapor is developed. The
sensor “senses” the vapor and its resistance increases
gradually. When the resistance reaches the value set
according to the menu, supplementary cooking is started.
The time of supplementary cooking is determined by
experiment with each food category and inputted into the
LSI.
An example of how the sensor works:
(BAKED POTATOES)
1. Potatoes at room temperature. Vapor is emitted
very slowly.
2. Select desired Sensor setting. Touch START pad.
The coil of shut-off relay (RY1, RY6) is energized, the
oven lamp and cooling fan motor are turned on, but
the power transformer is not turned on.
3. After about 16 seconds, the cook relay (RY2) is
energized. The power transformer is turned on,
microwave energy is produced and first stage is
started. The 16 seconds is the cooling time required
to remove any vapor from the oven cavity and sensor.
NOTE: During this first stage, do not open the door or
touch STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food, the display switches over to the remaining
cooking time and the timer counts down to zero. At
this time, the door may be opened to stir, turn, or
season food.
5. When the timer reaches zero, an audible signal
sounds. The shut-off relay and cook relay are
de-energized and the power transformer, oven lamp,
etc. are turned off.
6. Opening the door or touching the STOP/CLEAR pad,
the time of day will reappear on the display and the
oven will revert to an OFF condition.
2-3
Operation
AUTO DEFROST COOKING
MONITOR SWITCH
The AUTO DEFROST key is a special function key to
defrost meats and poultry faster and better. AUTO DEFROST automatically defrosts roast beef, chicken etc..
When the AUTO DEFROST is selected and the food
weight is entered by using the AUTO DEFROST pad, the
oven will cook according to the special cooking sequence.
The monitor switch is mounted on the middle position of
latch hook. It is activated (the contacts opened) by the
lower latch head while the door is closed. The switch
is intended to render the oven inoperative by means of
blowing the monitor fuse when the contacts of the relay
RY1 and primary interlock switch fail to open when the
door is opened.
Component Descriptions
DOOR SENSING AND PRIMARY INTERLOCK SWITCH
The door sensing switch, in the third door switch system
is mounted on the right latch hook. The primary and
monitor interlock switch is mounted on the left latch hook.
They are activated by the latch heads on the door. When
the door is opened, the switches interrupt the circuit to
all components. A cook cycle cannot take place until the
door is firmly closed, thereby activating both interlock
switches. The third door switch system consists of the
door sensing switch and secondary interlock relay
located on the control circuit board.
Functions:
1. When the door is opened, the monitor switch
contacts close (to the ON condition) due to their
being normally closed. At this time, the door sensing
and primary interlock and third door switches are in
the OFF condition (contacts open) due to their being
normally open contact switches.
2. As the door goes to a closed position, the monitor
switch contacts are first opened and then the door
sensing switch, third door switch and the primary
interlock switch contacts close. (On opening the door,
each of these switches operate inversely.)
3. If the door is opened, and the relay RY1 and the
primary interlock switch contacts fail to open, the
monitor fuse blows simultaneously with closing of the
monitor switch contacts.
Monitor switch
Latch hook left
Latch
head
Before replacing a blown monitor fuse, test the door
sensing switch, primary interlock switch, Relay (RY1)
and monitor switch for proper operation.
Primary
interlock switch
Latch hook right
3rd door switch
Latch
head
Monitor fuse and switch are replaced as an assembly.
Door
sensing switch
THIRD DOOR SWITCH
Door handle
The switch is activated by the latch heads, while the door
is closed. When the door is opened, the switch interrupts
the circuit to the power transformer. This switch prevents
power transformer engaging and microwave when the
door opened.
Figure 2-3. Door Sensing Switch, Monitor Switch,
Third Door Switch And Primary Interlock Switch
2-4
Operation
MAGNETRON THERMAL CUT-OUT
Humidity Sensor Circuit
The thermal cut-out, located on the waveguide, is
designed to prevent damage to the magnetron if an over
heated condition develops in the magnetron due to
cooling fan failure, obstructed air guide, dirty or blocked
air intake, etc.
Under normal operation, the thermal cut-out remains
closed. However, when abnormally high temperatures
are reached within the magnetron, the thermal cut-out will
open at 257°F (125°C) causing the oven to shut down.
The magnetron thermal cut-out is not reset at room
temperature.
(1) Structure of Absolute Humidity Sensor:
The absolute humidity sensor includes two
thermistors as shown in the illustration. One
thermistor is housed in the closed vessel filled with
dry air while another in the open vessel. Each sensor
is provided with the protective cover made of metal
mesh to be protected from the external airflow.
Ventilation
openings
OVEN THERMAL CUT-OUT
Thermistor
element
Thermistor
element
Sensing part
(Closed vessel)
Sensor
case
View of sensor case removed
Cross section view
(2) Operational Principle of Absolute Humidity Sensor:
The figure below shows the basic structure of an
absolute humidity sensor. A bridge circuit is formed
by two thermistors and two resistors (R1 and R2).
The output of the bridge circuit is to be amplified by
the operational amplifier. Each thermistor is supplied
with a current to keep it heated at about 150°C
(302°F), the resultant heat is dissipated in the air and
if the two thermistors are placed in different humidity
conditions they show different degrees of heat
conductivity leading to a potential difference between
them, causing an output voltage from the bridge
circuit, the intensity of which is increased as the
absolute humidity of the air increases. Since the
output is very minute, it is amplified by the
operational amplifier.
C
R1
S
R2
Operational
amplifier
Output
voltage
+
R3
S : Thermistor
open vessel
C : Thermistor
closed vessel
Absolute humidity vs,
output voltage characterist
Output voltage
The thermal cut-out, located on the side of the steam
duct, is designed to prevent damage to the unit if foods
in the oven catch fire due to over heating produced by
improper setting of cooking time or failure of control unit.
Under normal operation, the thermal cut-out remains
closed. However, when abnormally high temperatures
are reached within the oven cavity, the thermal cut-out
will open at 302°F (150°C) causing the oven to shut
down. When the thermal cut-out has cooled, the thermal
cut-out closes at 266°F (130°C)
Sensing part Sensing part
(Open vessel) (Closed vessel)
Sensing part
(Open vessel)
Absolute humidity (g/m 2 )
2-5
Operation
(3) Detector Circuit of Absolute Humidity Sensor
Circuit:
This detector circuit is used to detect the output
voltage of the absolute humidity circuit to allow the
LSI to control sensor cooking of the unit. When the
unit is set in the sensor cooking mode, 16 seconds
clearing cycle occurs then the detector circuit starts
to function and the LSI observes the initial voltage
available at its AN6 terminal.
With this voltage given, the switches SW1 to SW5 in
the LSI are turned on in such a way as to change the
resistance values in parallel with R50-1. Changing
the resistance values results in that there is the same
potential at both F-3 terminal of the absolute
humidity sensor and AN7 terminal of the LSI. The
voltage of AN6 terminal will indicate about -2.5V.
This initial balancing is set up about 16 seconds after
the unit is put in the Sensor Cooking mode.
As the sensor cooking proceeds, the food is heated
to generate moisture by which the resistance
balance of the bridge circuit is deviated to increase
the voltage available at AN6 terminal of the LSI.
Then the LSI observes that voltage at AN6 terminal
and compares it with its initial value, and when the
comparison rate reaches the preset value (fixed for
each menu to be cooked), the LSI causes the unit to
stop sensor cooking; thereafter, the unit goes in the
next operation automatically.
When the LSI starts to detect the initial voltage at
AN6 terminal 16 seconds after the unit has been put
in the Sensor Cooking mode, if it is not possible to
balance, of the bridge circuit due to disconnection of
the absolute humidity sensor, ERROR will appear on
the display and the cooking is stopped.
1) Humidity sensor circuit:
IC2(IZA495DR)
620k
300k
C. Thermistor in
closed vessel
S. Thermistor in
open vessel
0.1
µF
R51
3.32k 1.8k
10
VA : -15V
5
63
6
62
150k
7
61
75k
8
60
3
5
+
10k
-
SW1
P30
SW2
P31
SW3
P32
SW4
P33
SW5
P34
AN7
0.01µF
0.015µF
0.01µF
11
F-1
C
F-3
3.57k
F-2
64
37.4k
47k
S
4
LSI
(IC1)
2
6
AN6
47k
360k
9
12
VA : -15V
1
VC : -5V
2-6
Troubleshooting and Testing
Troubleshooting Guide
When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the
checks. Many of the possible causes of trouble will require that a specific test be performed. These tests are
given a procedure letter which will be found in the “Test Procedure “section.
If the oven becomes inoperative because of a blown monitor fuse, check the monitor switch, relay (RY1) primary
interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the monitor fuse. If the
monitor fuse is replaced, the monitor switch must also be replaced. Use part FFS-BA037WRKZ as an assembly.
Whenever troubleshooting is performed with the power supply cord disconnected. It may in, some cases, be
necessary to connect the power supply cord after the outer case has been removed, in this event:
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge high voltage capacitor, wait for 60 seconds and then short-circuit the connection of the
high-voltage capacitor (that is the connecting lead of the high-voltage rectifier) against the chassis with the
use of an insulated screwdriver.
4. Disconnect the leads to the primary of the power transformer.
5. Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.
6. After that procedure, reconnect the power supply cord.
When the testing is completed:
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge high voltage capacitor, wait for 60 seconds and then short-circuit the connection of the
high-voltage capacitor (that is the connecting lead of the high-voltage rectifier) against the chassis with the
use of an insulated screwdriver.
4. Reconnect the leads to the primary of the power transformer.
5. Reinstall the outer case (cabinet).
6. Reconnect the power supply cord after the outer case is installed.
7. Run the oven and check all functions.
Microwave ovens should not be run empty. To test for the presence of microwave energy within a cavity, place a cup
of cold water on the oven turntable, close the door and set the power to HIGH and then set the microwave timer for
two (2) minutes. When the two minutes has elapsed (timer at zero) carefully check that the water is now hot. If the
water remains cold carry out Before Servicing procedure and re-examine the connections to the component being
tested.
When all service work is completed and the oven is fully assembled, the microwave power output should be checked
and a microwave leakage test should be carried out.
3-1
TEST PROCEDURE
L
PROBLEM
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
A
MAGNETRON
B
POWER TRANSFORMER
C
H.V. RECTIFIER ASSEMBLY
D
HIGH VOLTAGE CAPACITOR
E
PRIMARY INTERLOCK SWITCH
F
SECONDARY INTERLOCK SYSTEM
G
MONITOR SWITCH
H
MONITOR FUSE
E
THIRD DOOR SWITCH
I
THERMAL CUT-OUT
K
TOUCH CONTROL PANEL
K
KEY UNIT
L
RELAY RY-1
L
RELAY RY-2
N
FOIL PATERN ON PWB.
O
AH SENSOR
Replace
OVEN LAMP OR SOCKET
Replace
FAN MOTOR
Replace
Check
TURNTABLE MOTOR
LOOSE WIRING
Check
SHORTED IN POWER CORD
Check
NO POWER AT OUTLET
Check
LOW VOLTAGE
O
NOISE FILTER
RELAY RY-3 (not used)
RELAY RY-5 (not used)
RELAY RY-6
3-2
Function of AUTO DEFROST does not operate properly.
Function of sensor cooking does not operate properly except HIGH
power.
Extremely uneven heating is produced in oven load (food).
COOKING CONDITION
Low or no power is produced during microwave cooking (The food is
heated incompletely or not heated at all)
Oven does not go into a cook cycle, when START pad is touched.
Turntable motor operates normally but cooling fan motor does not
operate.
Oven lamp lights, but turntable motor does not operate.
Cooking cycle runs 1 minute then shuts down.
OFF CONDITION
Oven lamp does not light in cook cycle. (It lights when door is
opened).
Oven lamp does not light with door opened.
Display does not operate properly when STOP/CLEAR pad is touched.
(The time of day should appear on the display with beep sound.)
"ENJOY" does not appear in display when power cord is first plugged
into wall receptacle.
CONDITION
Monitor fuse blows when power cord is plugged into wall receptacle
Home fuse blows when power cord is plugged into wall receptacle.
Troubleshooting and Testing
(MICROWAVE)
Troubleshooting and Testing
Test Procedures
Procedure
Letter
A
Component Test
MAGNETRON ASSEMBLY TEST
HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION
SHOULD BE OBSERVED.
DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN
COMPONENTS OR WIRING.
To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check
across the magnetron filament leads should indicate less than 1 ohm.
To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads
and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance
the magnetron is grounded and must be replaced.
Power output of the magnetron can be measured by performing a water temperature rise test. This
test should only be used if above tests do not indicate a faulty magnetron and there is no defect in
the following components or wiring: silicon rectifier, high voltage capacitor and power transformer.
This test will require a 16 ounce (453cc) measuring cup and an accurate mercury thermometer or
thermocouple type temperature tester. For accurate results, the following procedure must be
followed carefully:
1. Fill the measuring cup with 16 oz. (453cc) of tap water and measure the temperature of the water
with a thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple
through the water until the temperature stabilizes. Record the temperature of the water.
2. Place the cup of water in the oven. Operate oven at POWER HI(HIGH) selecting more than 60
seconds cook time. Allow the water to heat for 60 seconds, measuring with a stop watch, second
hand of a watch or the digital read-out countdown.
3. Remove the cup from the oven and again measure the temperature, making sure to stir the
thermometer or thermocouple through the water until the maximum temperature is recorded.
4. Subtract the cold water temperature from the hot water temperature. The normal result should
be 22 to 43°F (12.2 to 23.8°C) rise in temperature. If the water temperatures are accurately
measured and tested for the required time period the test results will indicate if the magnetron
tube has low power output (low rise in water temperature) which would extend cooking time or
high power output (high rise in water temperature) which would reduce cooking time. Because
cooking time can be adjusted to compensate for power output, the magnetron tube assembly
should be replaced only if the water temperature rise test indicates a power output well beyond
the normal limits. The test is only accurate if the power supply line voltage is 117 volts and the
oven cavity is clean.
3-3
Troubleshooting and Testing
Procedure
Letter
B
Component Test
POWER TRANSFORMER TEST
DO NOT TOUCH THE COMPONENTS OF THE POWER TRANSFORMER WHILE POWER
TRANSFORMER IS ENERGIZED. IT IS DANGEROUS BECAUSE THIS HAS HIGH VOLTAGE
COMPONENTS. (HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO
DO NOT ATTEMPT TO MEASURE THE FILAMENT AND HIGH VOLTAGE.)
1.
2.
3.
4.
5.
6.
7.
8.
C
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
Disconnect the primary input terminals and measure the resistance of the transformer with an
ohmmeter. Check for continuity of the coils with an ohmmeter. On R x 1 scale, the resistance of
the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be
approximately 84.4 ohms; the resistance of filament coil should be less than 1 ohm.
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
HIGH VOLTAGE RECTIFIER TEST
1.
2.
3.
4.
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the
resistance across the terminals and observe, reverse the leads to the rectifier terminals and
observe meter reading. If a short is indicated in both directions, or if an infinite resistance is
read in both directions, the rectifier is probably defective and should be replaced.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.
3-4
Troubleshooting and Testing
Procedure
Letter
D
Component Test
HIGH VOLTAGE CAPACITOR TEST
1.
2.
3.
4.
5.
6.
7.
8.
E
PRIMARY INTERLOCK SWITCH AND THIRD DOOR SWITCH TEST
1.
2.
3.
4.
5.
6.
7.
8.
F
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input
leads and check for short or open between the terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate
continuity for a short time and should indicate approximately 10 M once the capacitor is
charged. If the above is not the case, check the capacitor with an ohmmeter to see if it is
shorted between either of the terminals and case. If it is shorted, replace the capacitor.
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO)
terminal of the switch. The meter should indicated an open circuit with the door open and a
closed circuit with the door closed. If improper operation is indicated, replace the switch.
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
SECONDARY INTERLOCK SYSTEM TEST
DOOR SENSING SWITCH
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
4. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO)
terminal of the switch. The meter should indicate an open circuit with the door open and a closed
circuit with the door closed. If improper operation is indicated, replace the door sensing switch.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
3-5
Troubleshooting and Testing
Procedure
Letter
F
Component Test
SECONDARY INTERLOCK RELAY
1.
2.
3.
4.
5.
6.
7.
8.
G
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
Disconnect two (2) wire leads from the tab terminal of the secondary interlock relay (RY2).
Check the state of the relay contacts using a ohmmeter. The relay contacts should be open. If
the relay contacts are closed, replace the circuit board entirely or the relay itself.
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
MONITOR SWITCH TEST
1.
2.
3.
4.
5.
6.
7.
8.
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
Before performing this test, make sure that the secondary interlock relay and the primary
interlock switch are operating properly, according to the above Test Procedure. Disconnect the
wire lead from the monitor switch (NC) terminal. Check the monitor switch operation by using
the ohmmeter as follows. When the door is open, the meter should indicate a closed circuit.
When the monitor switch actuator is pushed by a screwdriver through the lower latch hole
on the front plate of the oven cavity with the door opened (in this condition the plunger of the
monitor switch is pushed in), the meter should indicate an open circuit. If improper operation is
indicated, the switch may be defective. After testing the monitor switch, reconnect the wire lead
to the monitor switch (NC) terminal and check the continuity of the monitor circuit.
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
Monitor switch
Ohmmeter
Latch Hook Left
Screwdriver
Primary
Interlock Switch
3-6
Troubleshooting and Testing
Procedure
Letter
H
Component Test
BLOWN MONITOR FUSE TEST
1.
2.
3.
4.
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
If the monitor fuse is blown when the door is opened, check the primary interlock switch, door
sensing relay (RY1), and monitor switch according to the “TEST PROCEDURE” for those
switches before replacing the blown monitor fuse.
If the monitor fuse is blown by improper switch operation, the monitor fuse and switch
must be replaced with “monitor fuse and switch assembly” part number FFS-BA012WRK0,
even if the monitor switch operates normally. The monitor fuse and switch assembly is
packed with 20 ampere fuse and switch.
5.
6.
7.
8.
I
OVEN THERMAL CUT-OUT (on the side of steam duct)
1.
2.
3.
4.
5.
6.
7.
8.
J
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
A continuity check across the thermal cut-out terminals should indicate a closed circuit
unless the temperature of the thermal cut-out reaches approximately 302°F (150°C).
The thermal cut-out reset automatically at approximately 266°F (130°C). If the thermal cut-out
has operated under the normal condition, replace the thermal cut-out. An open thermal cut-out
indicates overheating of the oven cavity.
Reconnect all leads removed from components during testing.
Reinstall the outer case (cabinet).
Reconnect the power supply cord after the outer case is installed.
Run the oven and check all functions.
NOISE FILTER TEST
1. Disconnect power supply cord, and remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor. (See Warnings and
Instructions on page 3-1)
4. Disconnect the leads to the primary of the power transformer.
5. Using an ohmmeter, check between the terminals as described
in the table below. If incorrect readings are obtained, replace
the noise filter.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect power supply cord after the outer case is installed.
9. Run oven and check all functions.
MEASURING POINT
NOISE FILTER
N
H
FUSE 20A
NOISE SUPPRESSION COIL
LINE CROSS CAPACITOR
0.22µF / AC 250V
LINE BYPASS
CAPACITOR
0.0033µF / AC 125V
GRY
RED
INDICATION OF OHMMETER
Between N and H
Open circuit.
Between terminal N and GRAY
Short circuit.
Between terminal H and RED
Short circuit.
3-7
LINE BYPASS
CAPACITOR
0.0033µF / AC 125V
Troubleshooting and Testing
Procedure
Letter
K
Component Test
TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc.
Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with
only a voltmeter and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and
Key Unit and troubleshooting by unit replacement is described according to the symptoms indicated.
1. Key Unit
Note : Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Unit.
The following symptoms indicate a defective control unit. Replace the control unit.
2-1 In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) All digits in the figure flicker.
2-3 Other possible troubles caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
d) Proper temperature measurement is not obtained.
When defective components, the Control Unit or Key Unit are replaced, the defective part
or parts must be properly packed for return in the shipping carton, with its cushion
material in which the new replacement part was shipped to you.
3-8
Troubleshooting and Testing
Procedure
Letter
L
Component Test
RELAY TEST
1.
2.
3.
4.
5.
Disconnect the power supply cord, and then remove outer case.
Open the door and block it open.
Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
Disconnect the leads to the primary of the power transformer.
Ensure that these leads remain isolated from other components and oven chassis by using
insulation tape.
6. After that procedure, re-connect the power supply cord.
7. Remove the outer case and check voltage between Pin #7 and 9 of the 9- pin connector (A) on
the control unit with an A.C. voltmeter. The meter should indicate 120 volts, if not, check the
oven circuitry.
Shut-off, Cook and Heater Relay Test
These relays are operated by DC voltage.
Check voltage at the relay coil with a DC voltmeter during the microwave cooking operation or convection cooking operation.
DC voltage indicated ----------------------------- Defective relay.
DC voltage not indicated ------------------------ Check diode which is connected to the relay
coil. If diode is good, control unit is defective.
RELAY SYMBOL
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
Approx. 2.5V D.C.
Oven lamp / Turntable motor
RY2(COOK)
Approx. 2.4V D.C.
Power transformer
RY6
Approx. 2.5V D.C.
Cooling fan motor
8. If any abnormal condition is detected, replace the control unit.
9. Disconnect the power supply cord and then remove outer case.
10. Open the door and block it open.
11. Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
12. Reconnect all leads removed from components during testing.
13. Re-install the outer case (cabinet).
14. Reconnect the power supply cord after the outer case is installed.
15. Run the oven and check all functions.
M
AUTO DEFROST TEST
1. Place one cup of water in the center of the turntable tray in the oven cavity.
2. Close the door, touch the “AUTO DEFROST” pad and touch the Number pad “2”, then “2” again,
then “0” (2 = Steaks & Chops, 2,0 = 2.0lbs). Touch the “START” pad.
3. After 2 seconds, the oven is in AUTO DEFROST cooking condition.
4. The oven will operate as follows.
WEIGHT
2.0lbs
1ST STAGE
LEVEL TIME
70%
47sec.
2ND STAGE
3RD STAGE
LEVEL TIME LEVEL
TIME
50%
32sec.
30%
40sec.
5. If improper operation is indicated, the control unit is probably defective and should be checked.
3-9
Troubleshooting and Testing
Procedure
Letter
N
Component Test
AH SENSOR TEST
Checking the initial sensor cooking condition:
WARNING: The oven should be fully assembled before following procedure.
1. The oven should be plugged in at least two minutes before sensor cooking.
2. Room temperature should not exceed 95°F (35°C).
3. The unit should not be installed in any area where heat and steam are generated. The unit
should not be installed, for example, next to a conventional surface unit. Refer to the
“Installation Section”.
4. Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity.
To permit adequate ventilation, be sure to install so as not to block these vents. There should be
some space for air circulation.
5. Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any
moisture with a dry cloth or paper towel.
6. The Sensor works with food at normal storage temperature. For example, chicken pieces would
be at refrigerator temperature and canned soup at room temperature.
7. Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The
sensor will detect vapor given of by the spray and turn off before food is properly cooked.
8. After the oven is started on sensor cooking condition, if the sensor has not detected the vapor of
the food within 30 minutes, ERROR will appear and the oven will shut off.
WATER LOAD COOKING TEST
WARNING: The oven should be fully assembled before following procedure.
Make sure the oven has been plugged in at least two minutes before checking sensor cook
operation. The cabinet should be installed and screws tightened.
1. Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
2) Place the container on the center of tray in the oven cavity.
3) Close the door.
4) Touch BAKED POTATO pad and number pad 1. Now, the oven is in the sensor cooking
condition and “BAKED POTATO” will appear in the display.
5) The oven will operate for the first 16 seconds, without generating microwave energy.
When the AH sensor is defective (open or short), Error will appear in the display after 16
seconds cleaning time. If ERROR appears check sensor wire connections and/or AH sensor.
NOTE: ERROR will appear if the door is opened or STOP/CLEAR pad is touched during first stage
of sensor cooking.
6) After approximately 16 seconds, microwave energy is produced.
If ERROR is displayed or the oven does not turn off, replace the humidity sensor or check the
control unit, refer to explanation on next page.
3-10
Troubleshooting and Testing
Procedure
Letter
Component Test
1. TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT
To determine if the sensor is defective, the simplest method is to replace it with a new replacement
sensor.
1. Disconnect the power supply cord, and then remove outer case.
2. Discharge high voltage capacitor. (See Warnings and Instructions on page 3-1)
3. Remove the AH sensor.
4. Install the new AH sensor.
5. Re-install the outer case (cabinet).
6. Reconnect the power supply cord after the outer case is installed.
7. Reconnect the oven to the power supply and check the sensor cook operation as follows:
a) Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
b) Place the container on the center of tray in the oven cavity.
c) Close the door.
d) Touch SENSOR COOK pad and number 1 pad.
e) Touch Start pad. The control panel is in automatic Sensor operation.
f) The display will start to count down the remaining cooking time, and the oven will turn off
automatically after the water is boiling (bubbling).
If new sensor dose not operate properly, the problem is with the control unit.
2. CHECKING CONTROL UNIT
1.
2.
3.
4.
5.
6.
Disconnect the power supply cord, and then remove outer case.
Discharge high voltage capacitor.
Disconnect the wire leads from the cook relay.
Disconnect the sensor connector that is mounted to lower portion of control panel.
Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.
Reconnect oven to the power supply and check the sensor cook operation proceed as follows:
6-1. Touch BAKED POTATO pad and number 1 pad.
6-2. Touch Start pad. The control panel is in the sensor cooking operation.
6-3. After approximately 20 seconds, push plunger of select switch for more than 3 seconds.
This condition is same as judgement by AH sensor.
6-4. After approximately 3 seconds, the display shows “ X X . X X “ which is the remaining
cooking time, and the display count down.
If the above is not the case, the control unit is probably defective.
If the above is proper, the AH sensor is probably defective.
R1,R2 : 22 ± 1% 1/2W
R3 ...... : 4.3k ± 5% 1/4W
R4 ...... : 1M ± 5% 1/4W
Plunger
NC
NO
To connector (F)
on Control Unit.
1
F-1
F-2
2
3
COM
COM NO
R1
F-3
CONNECTOR
R2
R3
R4
3-11
NC
Troubleshooting and Testing
Notes
3-12
Component Teardown
TO PREVENT AN ELECTRIC SHOCK, TAKE THE FOLLOWING PRECAUTIONS:
1. BEFORE WIRING:
1) Disconnect the power supply.
2) Open the door and wedge the door open.
3) Discharge the high voltage capacitor and wait for 60 seconds.
2. DO NOT LET WIRE LEADS TOUCH TO THE FOLLOWING PARTS:
1) High voltage parts:
Magnetron, High voltage transformer, High voltage capacitor and High voltage rectifier assembly.
2) Hot parts:
Oven lamp, Magnetron, High voltage transformer and Oven cavity.
3) Sharp edge:
Bottom plate, Oven cavity, Waveguide flange, Chassis support and other metallic plates.
4) Movable parts (to prevent a fault)
Fan blade, Fan motor, Switch, Switch lever, Open button.
3. Do not catch the wire leads in the outer case cabinet.
4. Insert the positive lock connector completely until its pin is locked. Make sure that the wire leads should
not come off even if the wire leads are pulled.
5. To prevent an error function, connect the wire leads correctly, referring to the Pictorial Diagram.
AVOID POSSIBLE EXPOSURE TO MICROWAVE ENERGY. PLEASE FOLLOW INSTRUCTIONS BELOW
BEFORE OPERATING THE OVEN.
1. Disconnect the power supply cord.
2. Make sure that a definite” click” can be heard when the microwave oven door is unlatched. (Hold the
door in a closed position with one hand, then push the door open button with the other, this causes
the latch leads to rise, it is then possible to hear a “click’ as the door switches operate.)
3. Visually check the door and cavity face plate for damage (dents, cracks, signs of arcing etc.).
Carry out any remedial work that is necessary before operating the oven.
DO NOT OPERATE THE OVEN IF ANY OF THE FOLLOWING CONDITIONS EXIST;
1. Door does not close firmly.
2. Door hinge, support or latch hook is damaged.
3. The door gasket or seal is damaged.
4. The door is bent or warped.
5. There are defective parts in the door interlock system.
6. There are defective parts in the microwave generating and transmission assembly.
7. There is visible damage to the oven.
DO NOT OPERATE THE OVEN:
1. Without the RF gasket (Magnetron).
2. If the wave guide or oven cavity are not intact.
3. If the door is not closed.
4. If the outer case (cabinet) is not fitted.
Disconnect oven from power supply before removing outer case.
Discharge high voltage capacitor before touching any oven components or wiring after removing outer
case.
4-1
Component Teardown
Outer Case Removal
Power Transformer Removal
REMOVAL
1. Disconnect the oven power supply cord and remove
outer case.
2. Discharge high voltage capacitor.
1. Disconnect oven from power supply before
removing outer case.
2. Discharge the high voltage capacitor before
touching any oven components or wiring.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
1. Disconnect the power supply cord.
2. Remove six (6) screws holding top duct and remove.
3. Remove the eight (8) screws on the back side of the
outer case and two ducts to the back plate.
4. Remove the four (4) screws holding the right and left
sides of the outer case cabinet to the bottom plate.
5. Remove three (3) screws on top of the cabinet
directly behind the control panel.
6. Slide the entire outer case cabinet back out about 1
inch to free it from the retaining clips on the oven
cavity front plate.
7. Lift the entire outer case cabinet from the unit.
3. Disconnect filament leads of transformer from the
magnetron and capacitor.
4. Disconnect high voltage lead of capacitor from the
transformer.
5. Disconnect wire leads from transformer.
6. Remove two (2) screws holding the transformer to
the base cabinet.
RE-INSTALL
Magnetron Removal
1. Disconnect the oven power supply cord and remove
outer case.
2. Discharge high voltage capacitor.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
3. Disconnect filament lead of transformer from
magnetron.
4. Disconnect high voltage wire lead from magnetron.
5. Carefully remove four (4) mounting screws hold the
magnetron to waveguide, when removing the screws
hold the magnetron to prevent it from falling.
6. Remove the magnetron from the unit with care so the
magnetron tube does not hit by any metal objects
around the tube.
1. Rest the transformer on the base cabinet with its
primary terminals toward rear cabinet.
2. Insert the two edges of the transformer into two metal
tabs of the base cabinet.
3. Make sure the transformer is mounted correctly to
the corners underneath those tabs.
4. After re-installing the transformer, secure transformer
with two screws to the base cabinet, one is with an
outer tooth washer and the other is without outer
tooth washer.
5. Re-connect the wire leads (primary and high voltage)
and high voltage lead to the transformer and filament
leads of transformer to the magnetron and capacitor,
referring to the Wiring Diagram.
Hot (orange) wire must be connected to the power
transformer terminal nearest to the transformer
mounting screw.
6. Re-install the outer case and check that the oven is
operating properly.
When replacing the magnetron, be sure the R.F.
Gasket is in place and mounting screws are
tightened securely.
4-2
Component Teardown
High Voltage Rectifier Removal
Turntable Motor/Coupling Removal
1. Disconnect the oven power supply cord and remove
outer case.
2. Discharge high voltage capacitor.
1. Disconnect the power supply cord.
2. Remove the turntable tray, and the turntable support
out of the oven cavity.
3. Turn the oven on its back and remove the screws
holding the bottom duct to bottom of the oven.
4. Remove the one (1) screw holding the turntable
motor cover to the base plate and take off the
turntable motor cover.
5. Disconnect wire leads from the turntable motor.
6. Remove the two (2) screws holding the turntable
motor.
7. Remove turn table motor, and if replacing coupling,
push coupling through the hole into inside the cavity.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
3. Remove one (1) screw holding the rectifier assembly
to the capacitor holder.
4. Disconnect the rectifier assembly from the capacitor
and magnetron.
When replacing the silicon rectifier assembly, the
ground side terminal must be secured firmly with a
grounding screw.
Oven Lamp and Lamp Socket
Removal
1. Disconnect oven from power supply and remove
outer case.
2. Discharge high voltage capacitor.
High Voltage Capacitor Removal
1. Disconnect the oven power supply cord and remove
outer case.
2. Discharge high voltage capacitor.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
3.
4.
5.
6.
3. Disconnect high voltage wire leads and rectifier
assembly from high voltage capacitor and
magnetron.
4. Disconnect filament lead of transformer from high
voltage capacitor.
5. Disconnect high voltage wire lead of capacitor from
transformer.
6. Remove one (1) screw and washer holding rectifier
from the capacitor holder.
7. Remove one (1) screw holding the capacitor holder
to the rear cabinet.
8. Remove the capacitor from the holder.
Unplug wires from the lamp socket.
Remove lamp from socket.
Twist the lamp socket to free it from the holder.
Pull lamp socket through hole. The oven lamp socket
is now free.
Figure 4-1. Oven Lamp Socket
4-3
Component Teardown
INSTALLATION
Fan Motor Removal
1. Install fan motor to fan duct with the two (2) screws.
2. Install the fan blade to the fan motor shaft according
to the following procedure:
1) Hold the center of the bracket which supports the
shaft of the fan motor on the flat table.
2) Apply the screw lock tight into the hole (for shaft)
of the fan blade.
3) Install the fan blade to the shaft of fan motor by
pushing the fan blade with a small, light weight,
ball peen hammer or rubber mallet.
REMOVAL
1. Disconnect the oven power supply cord and remove
outer case.
2. Discharge high voltage capacitor.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
3. Disconnect the wire leads from the fan motor.
4. Remove three (3) screws holding chassis support to
rear cabinet, waveguide and control panel back plate.
5. Remove the chassis support from the oven.
6. Disconnect wire leads from the fan motor.
7. Release main harness from the hole of the fan duct.
8. Release one (1) tab holding the fan duct to the rear
cabinet.
9. Release one (1) tab holding the fan duct to the air
guide (Right).
10. Remove the fan duct assembly from the oven.
11. Remove the fan blade from the fan motor shaft
according the following procedure:
1) Hold the edge of the rotor of the fan motor by
using a pair of groove joint pliers.
* Do not hit fan blade with excessive force when
installing because the bracket may be disfigured.
* Make sure that the fan blade rotates smooth
after installation.
* Make sure the axis of the shaft is not slanted.
3.
4.
5.
6.
Reset the fan duct assembly to its install position.
Install tabs of fan duct to rear cabinet and air guide.
Install magnetron air guide with the one (1) screw.
Reinstall the main harness and thermistor harness to
each hole of the fan duct.
7. Reinstall the chassis support to the control panel
back plate, waveguide and rear cabinet with the three
(3)screws.
8. Re-connect the wire leads to the fan motor, referring
to the pictorial diagram.
9. Re-install the fan motor grounding wire to the air
guide (Right) with one (1) screw.
Coil
Make sure that any pieces do not enter the gap
between the rotor and the stator of the fan motor
because the rotor is easily shaven by pliers and
metal pieces may be produced.
* Do not touch the pliers to the coil of the fan
motor because the coil may be cut or damaged.
* Do not disfigure bracket by touching with pliers.
Do not reuse the removed fan blade because the
hole (for shaft) may be larger than normal.
Groove
joint pliers
Bracket
Stator
Gap Rotor
Rear View
Shaft
Axis
These are the positions that
should be pinched with pliers.
Stator
Shaft
Rotor
Side View
2) Remove the fan blade from the shaft of the fan
motor by pulling and rotating the fan blade with
your hand.
12. Remove the two (2) screws and nuts holding the fan
motor to the fan duct.
13. Now, the fan motor is free.
Table
Center of
bracket
Figure 4-2. Fan Motor Components
4-4
Component Teardown
Power Supply Cord Replacement
Door Sensing Switch, Primary/Third
Interlock Switch and Monitor Switch
Replacement
REMOVAL
1. Disconnect the power supply cord.
2. Discharge high voltage capacitor.
REMOVAL
1. Disconnect the oven power supply cord and remove
outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
3. Disconnect the white and black wires of the power
supply cord from the noise filter.
4. Remove the one (1) screw holding the ground wire of
the power supply cord to the base cabinet.
5. Remove the power supply cord from the rear cabinet.
Re-install
1. Insert the power supply cord into the rear cabinet.
2. Connect the white and black wires of the power
supply cord into the terminal of noise filter, referring
to the Wiring Diagram.
3. Re-install the ground wire of the power supply cord to
the base cabinet with the one (1) screw.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
4. Disconnect the wire leads from the switch.
5. Remove the one (1) screw holding the latch hook
(right or left) to the oven cavity front plate, and
release the latch hook (right or left).
6. Keep pushing the stopper tub holding the switch to
the latch hook (right or left) and revolve the switch on
the pole.
7. Remove the switch from the latch hook (right or left).
8. Now, the switch is free.
Noise filter
GRY
RED
White wire
N
H
Black wire
Green wire
Power
supply cord
Rear Cabinet
Base Cabinet
Figure 4-3. Power Cord Connections
REINSTALL
1. Re-install each switch in its place. The door sensing
switch is in the lower position of the latch hook right.
The primary interlock switch is in the lower position of
the latch hook left. The monitor switch is in the upper
position of the latch hook left.
2. Hold the latch hook (right or left) to the oven cavity
front plate and secure with the one (1) screw.
3. Reconnect the wire leads to the switch.
4. Make sure that monitor switch is operating properly
and check continuity of the monitor circuit. Refer to
“Test Procedure” and “Adjustment procedure.
4-5
Component Teardown
ADJUSTMENT
Monitor switch
If the door sensing switch, primary interlock switch, third
interlock switch and monitor switch do not operate
properly due to a misadjustment, the following adjustment
should be made.
1. Disconnect the oven power supply cord and remove
outer case.
2. Open the oven door and block it open.
3. Discharge the high voltage capacitor.
Latch hook left
Latch
head
Primary
interlock switch
Latch hook right
3rd door switch
Latch
head
Door
sensing switch
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
Door handle
4. Loosen each one (1) screw holding the latch hook
right and the latch hook left to the oven cavity front
plate.
5. With door closed, adjust the latch hook right and the
latch hook left by moving them back and forth and
up and down. In and out play of the door allowed by
the latch hook right and the latch hook left should be
less than 0.5 mm. The vertical position of the latch
hook right and the latch hook left should be adjusted
so that the door sensing switch and the primary
interlock switch are activated with the door closed.
The horizontal position of the latch hook right and the
latch hook left should be adjusted so that the plunger
of the monitor switch is pressed with the door closed.
6. Secure the screws firmly.
7. Check all of the switches operation. If any switch has
not activated with the door closed, loosen the screws
and adjust the position of the latch hook right and the
latch hook left.
Figure 4-4. Door Switch Components
3. Monitor switch contacts close when door is opened.
4. The contact of door sensing switch and secondary
interlock switch open within 1.2mm gap between right
side of cavity face plate and door when door is open.
5. Re-install outer case and check for microwave
leakage around door with an approved microwave
survey meter. (Refer to Microwave Measurement
Procedure.)
After adjustment, check the following.
1. In and out play of door remains less than 0.5mm
when in the latched position. First check upper
position of latch hook, pushing and pulling upper
portion of door toward the oven face. Then check
lower portion of the latch hook, pushing and pulling
lower portion of the door toward the oven face. Both
results (play in the door) should be less than 0.5mm.
2. The door sensing switch, and secondary interlock
switch interrupt the circuit before the door can be
opened.
4-6
Component Teardown
Door Replacement
1. Disconnect the oven power supply cord and remove
outer case.
2. Open the door and block it open.
3. Discharge the high voltage capacitor.
The door on a microwave oven is designed to act
as an electronic seal preventing the leakage of
microwave energy from the oven cavity during the
cook cycle. This function does not require that the
door be airtight, moisture (condensation)-tight
or light-tight. Therefore, occasional appearance
of moisture, light or sensing of gentle warm air
movement around the oven door is not abnormal
and do not of themselves indicate a leakage of
microwave energy from the oven cavity. If such
were the case, the oven could not be equipped
with a vent, the very purpose of which is to exhaust
the vapor-laden air from the oven cavity.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
4. Close the door.
5. Remove two (2) door springs from door cam right,
oven hinge right, door cam left and oven hinge left.
6. Release the door cams right and left from the right
and left door cam pins of the door.
7. Remove the door cams right and left from the oven
cavity front plate.
8. Open the door assembly at an angle of more than
90½° with the oven cavity front plate.
9. To release the right and left door hinge pins of the
door assembly from the oven hinges right and left,
slide the door assembly to the left. When removing
the door assembly, hold the door assembly to
prevent it from falling.
10. Now, the door assembly is free.
Door Cam Left
Door Spring
Door Cam Right
Oven Hinge
Left
Door
Spring
Door
Assembly
Oven Hinge
Right
Figure 4-5. Door Replacement and Adjustment
NOTE: When the individual parts are replaced, refer to
“Door Disassembly”.
Left Door
Cam Pin
Door Cam Left
Door Assembly Re-install
1.
2.
3.
On reinstalling the door assembly, insert oven hinges
right and left into the right and left door hinge pins.
Insert and hook the door cams right and left to the
right and left door cam pins.
Reinstall the two (2) door springs between the door
cams and the oven hinges right and left.
Left Door
Hinge Pin
Oven Hinge
Left
Door
Assembly
Right Door
Cam Pin
Door Cam Right
Oven Hinge
Right
Right Door
Hinge Pin
Figure 4-6. Door Assembly Components
After any service to the door:
(A) Make sure that the door sensing switch and the
secondary interlock switch are operating properly.
(Refer to chapter “Test Procedures”.)
(B) An approved microwave survey meter should be
used to assure compliance with proper microwave
radiation emission limitation standards.
4-7
Component Teardown
Door Adjustment
Door Disassembly
When removing and/or loosening the oven hinges such
as in door replacement, the following adjustment criteria
are taken.
Door adjustment is performed with the door properly
installed and closed and while the oven hinges are loose.
1. Disconnect the power supply cord and remove outer
case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
1. Loosen screws holding the oven hinge right and the
oven hinge left to the bottom plate with screwdriver.
2. Adjust door by moving it so that the door is parallel
with the oven cavity front plate lines (right and left
side lines) and the door latch heads pass through the
latch holes correctly.
3. Tighten the screws holding the oven hinge right and
the oven hinge left to the bottom plate.
After adjustment, make sure of the following:
1. The door latch heads smoothly catch the latch hooks
through latch holes and the latch heads goes through
center of latch holes.
2. The door is positioned with its face pressed toward
oven cavity front plate.
3. Reinstall outer case cabinet and check for microwave
leakage around the door with an approved microwave
survey meter. (Refer to Microwave Measurement
Procedure.)
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
4. Remove the door assembly, referring to “Door
Replacement”.
5. Place the door assembly on a soft cloth with latch
heads facing up.
NOTE: As the engaging part of choke cover and door
frame are provided at 16 places, do not force any
particular part.
6. Replacement of the door components are as follows:
CHOKE COVER
7. Insert a putty knife (thickness of about 0.5mm) into
the gap A between the choke cover and door stopper
and between the choke cover and the door frame as
shown in Figure 4-7 to free engaging parts.
8. Pry the choke cover by inserting a putty knife in order
shown in Figure 4-7.
9. Now choke cover is free from door panel and door
frame.
Choke
Cover
Door Panel
Assembly
Putty Knife
Door
Frame
Figure 4-7. Door Disassembly
4-8
Component Teardown
Door Disassembly (Continued)
Control Assembly And CPU Unit
Removal
DOOR PANEL ASSEMBLY AND LEFT AND RIGHT
LATCH HEAD REMOVAL
CONTROL PANEL ASSEMBLY
10. Remove the fourteen (14) screws holding the door
panel assembly to the door frame.
11. Remove the door panel assembly from door frame.
12. Remove the one (1) screw holding the latch head R
to the door panel assembly.
13. Remove the latch spring R from the latch head R and
the handle lever.
14. Now, the latch head R is free.
15. Remove the one (1) screw holding the latch head L to
the door panel assembly.
16. Remove the latch spring L from the latch head L and
the handle lever.
17. Now, the latch head L is free.
18. Release the two (2) handle springs from the two (2)
handle levers.
19. Pull out the two (2) handle pins from the two (2)
handle levers.
20. Remove the two (2) handle levers from the door
panel.
21. Now, the door panel is free.
1. Disconnect the oven power supply cord and remove
outer case.
2. Open the oven door and block it open.
3. Discharge the high voltage capacitor.
To discharge the high voltage capacitor, wait for 60
seconds and then short-circuit the connection of
the high-voltage capacitor (that is the connecting
lead of the high-voltage rectifier) against the
chassis with the use of an insulated screwdriver.
4. Disconnect the 9-pin & 14-pin harness from the
connectors CN-D and CN-N on the power unit.
5. Remove the four (4) screws holding the control panel
assembly to the oven cavity front plate.
6. Now, the control panel assembly is free.
CPU UNIT
7. Disconnect the 12-pin (CN-S), 6-pin (CN-M) & 10-pin
(CN-L), 16-pin (CN-K) harness from the connectors
on the power unit.
8. Remove the eight (8) screws holding the CPU unit to
the panel sub assembly. See Figure 4-8.
9. Now, the CPU unit is free.
(8) Screws
Figure 4-8. Control Panel and CPU
4-9
Component Teardown
Notes
4-10
120V
60Hz
OL
NOISE SUPPRESSION COIL
FUSE
20A
NOTE:
*3.
1.
2.
PPL
FM
ORG
DM
E1
E2
E4
RY3
THERMISTOR
E3
RY5
A7
OVEN
THERMAL
CUT-OUT
CONTROL
UNIT
RY4
DOOR
SENSING
SWITCH
A1
B10
B8
B1
B2
B3
B4
B5
B6
A9
MAGNETRON
THERMAL
CUT-OUT
CIRCUITS SUBJECT TO CHANGE WITHOUT NOTICE
WIRE COLOR CODES ARE APPLICABLE TO PRIMARY CIRCUIT ONLY AND NOT
APPLICABLE TO LOW VOLTAGE CIRCUIT AND SECONDARY CIRCUIT.
HOT WIRE(S) MUST BE CONNECTED TO THE TERMINAL WITH BLUE MARK
ON THE LAMP SOCKET AND "H" MARK ON THE POWER SUPPLY CORD.
L.V.
TRANSFORMER
CONV.
THERMAL
CUT-OUT
RY1
(RY1)
F1
SECONDARY
INTERLOCK
RELAY
F3 F2
A3
AH SENSOR
RY2
E6
DAMPER
SWITCH
E5
RY6
A5
SCHEMATIC DIAGRAM (DOOR CLOSED,COOK OFF CONDITION)
(RY3)
(RY2)
(RY2)
(RY3)
(RY1)
H.V.
RECTIFIER
CAPACITOR
0.94
POWER
TRANSFORMER
MAGNETRON
Wiring Schematic
Oven Off Condition
3RD
DOOR
SWITCH
OVEN LAMP
0.0033 F AC125V
0.0033 F AC125V
RED・PNK
*
TURNTABLE MOTOR
BRN
CM
CONVECTION MOTOR
PNK
TTM
FAN MOTOR
5-1
DAMPER MOTOR
NOISE FILTER UNIT
PRIMARY INTERLOCK SWITCH
HEATING
ELEMENT
0.22 F AC250V
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
Wiring Diagrams
MONITOR SWITCH
Wiring Diagrams
Pictorial Diagram
CN-F
1 BLK
2 RED
3 WHT
AH SENSOR
CN-N
DOOR
SENSING
SWITCH
CN-E
RED
GRN
ORG
PNK
RED
6 PNK
5
4
3
2
1
RY3 (N.O.)
BRN
ORG
RED
RY2 (N.O.)
WHT
BLK
PPL
BRN
ORG
CN-A
PNK
RED
BLK
C9
RY1 (N.O.)
RY1 (COM.)
RY2 (COM.)
RY3 (COM.) BRN
12 345
CONTROL PANEL
CN-D
3
1
COM.
RY1
COM.
RY2
COM.
RY3
RY4
RY5
CN-B
1 2 3 4 5 6 7 8 9 10
C1
1 2 3 4 5 6 7 8 9 10 1112
CN-F
CN-A
N.O.
N.O.
N.O.
CN-E
6
5
4
3
2
1
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
GRY
GRY
GRY
WHT
GRN
ORG
COM
N.O.
THIRD
DOOR
SWITCH
N.O.
COM
ORG
RED
N.O. ORG
BRN
COM
MONITOR
SWITCH
WHT
N.C.
COM
PRIMARY
INTERLOCK
SWITCH
GRN
GRN
R
E
D
PNK
PNK
PNK
WHT
OVEN LAMP
& SOCKET
G
R
Y
COM
N.O. DAMPER
SWITCH
PNK
HEATING
ELEMENT
G
R
Y
GRY
PNK
TURNTABLE
MOTOR
BLK
BLK
ORG
OVEN
THERMAL
CUT-OUT
WHT
DAMPER
MOTOR
BRN
GRY
PNK
MAGNETRON
THERMAL
CUT-OUT
BLK
CONVECTION MOTOR
THERMISTOR
RED 2 RED
RED 1 RED
W
H
T
BLK
P
P
L
RED
RED
GRN
BLK
WHT
COOLING
FAN
MOTOR
POWER SUPPLY CORD
RED
PNK
CONV.
THERMAL
CUT-OUT
NOTE:
Hot (ORG) wire must be connected to the
power transformer terminal nearest to the
transformer mounting screw.
POWER TRANSFORMER
HIGH VOLTAGE
CAPACITOR
HIGH VOLTAGE COMPONENTS
BLK
G
R
Y
MAGNETRON
G
R
Y
RED
H
WHT
GRY
O
R
G
GRY
N
NOISE FILTER
AND FUSE
5-2
Parts List
DESCRIPTION
REF. NO.
Q’TY
ELECTRICAL PARTS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Power supply cord
Monitor fuse 20A and monitor switch (V-5220D-070) assembly
Noise filter
Primary interlock switch/Third door switch/Door sensing switch
Magnetron thermal cut-out 125°C
Oven thermal cut-out 150°C
Oven lamp
Oven lamp socket
Fan motor
Power transformer
H.V. Capacitor
H.V. Rectifier assembly
Magnetron
Turntable motor
Low voltage transformer
AH sensor assembly
1
1
1
3
1
2
1
1
1
1
1
1
1
1
1
1
CABINET PARTS
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Outer case cabinet
Base plate
Foot
Rear plate
Capacitor holder
Oven hinge (L)
Oven hinge (R)
Latch hook (R)
Latch hook (L)
Door cam (L)
Door cam (R)
Turntable motor cover
Front cover
Duct B
Duct C
1
1
4
1
1
1
1
1
1
1
1
1
1
1
1
CONTROL PANEL PARTS
32
33
34
35
36
37
38
Touch control assy
Display unit
Control panel angle
Grounding spring
PSU harness
Screw
Screw
1
1
1
1
1
8
4
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Oven cavity assembly (Not Replaceable)
Turntable support
Turntable tray
Glass mounting plate
Transformer mount angle
Cushion
Steam duct assembly
Turntable coupling
Waveguide cover
Light glass
Fan blade
Cooling fan duct
Chassis support
Noise unit angle
Cushion
Magnetron air guide
OVEN PARTS
6-1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Parts List
DESCRIPTION
REF. NO.
55
56
57
58
59
60
61
62
63
64
65
65
66
67
Thermal protection sheet
Thermo cover
Duct
Side trim L
Side trim R
Exhaust duct
Bottom angle
Inlet louver
Shipping angle
TT mounting angle
Door spring R (EW30MO55HS)
Door spring R (EW27MO55HS)
Door spring L (EW30MO55HS)/(EW27MO55HS)
Barrier
Q’TY
1
1
1
1
1
1
1
1
1
1
1
1
1
1
DOOR PARTS
1
1
1
1
1
1
10
2
68
69
70
71
72
73
74
75
Door frame assembly
Door panel
Choke cover
Latch head R
Latch head L
Latch head spring
Screw
Screw
76
77
78
79
80
81
82
83
84
85
86
Main wire harness
High voltage wire B
Grounding wire (Cooling fan motor)
Monitor caution label
NHW caution label
Operation manual
User caution
BIK label
GND caution label
Installation instructions
Menu label
WIRING/LABELS
1
1
1
1
1
1
1
1
1
1
1
SCREWS NUTS AND WASHERS
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
Screw
Screw
Screw
Screw
Screw
Special screw
Screw
Screw
Screw
Screw
Screw
Screw
Special nut
Screw
Screw
102
103
104
105
106
107
108
109
110
Switch lever
Switch lever
Air guide R
TT motor packing
Cushion
Trim dec L
Trim dec R
Power board holder
Power board
4
2
14
41
6
3
2
6
2
2
4
2
3
2
3
MISCELLANEOUS
1
1
1
1
2
1
1
1
1
6-2
Parts List
Oven And Cabinet Parts
98
84
96
6
16
95
7
45
94
104
8
83
20
106
42
94
48
99
80
87
5
92
2
94
102
51
1
4
25
39
55
82
21
88
13
92
103
91
12
105
57
47
100
64
101
24
67
41
4
4
90
56
86
90
90
90
53
97
46
40
106
96
109
14 15
18
26
10
90
79
3
66
99
52
96
90
50
22
93
23
19
28
88
90
19
100
6-3
9
90
90
88
65 19
49
110
2
43
27
11
106
54
44
Parts List
Cabinet And Frame Parts
29
89
30
89
17
89
31
90
89
90
90
58
90
90
91
59
107
90
62
63
61
108
90
91
61
63
60
90
6-4
Parts List
Control And Door Parts
34
CONTROL PANEL PARTS
38
35
37
32
33
36
70
75
72
69
74
DOOR PARTS
73
71
68
75
73
74
MISCELLANEOUS
Actual wire harness may be different than illustration.
76
77
78
6-5
Parts List
Packing and Accessories
41 TURNTABLE TRAY
TOP CROSS SUPPORT
85 INSTALLATION MANUAL
81 OPERATION MANUAL
DOOR PROTECTION SHEET
TOP BASE PAD
40 TURNTABLE SUPPORT
PLASTIC BAG
BOTTOM BASE PAD
VERTICAL CORNER POST
TRAY PAD
Not replaceable items.
PACKING CASE
PALLET
6-6