Frigidaire CGMV173KB User guide

All About
Servicing
OVER THE RANGE
MICROWAVE OVENS
1.7 Cu. Ft. Model With Standard And
Electronic Controls
™
Publication #5995546412 Part # 316439600 August 2009
Electrolux Major Appliances; North America
250 Bobby Jones Expwy
Augusta, GA 30907

Section 1 Basic Information
1-1
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.
© 2009 Electrolux Home Products, Inc.

Section 1 Basic Information
1-2
This Manual has been prepared to provide Service Personnel with Operation and Service Information for Frigidaire
Microwave Ovens CGMV173KB, CGMV173KW and CGMV174KF.
Table of Contents
Section 1 Basic Information
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 (Canadian Residents)................... 1-4
Before Servicing (All Other Countries).................... 1-4
Before Servicing................................................... 1-5
When Testing Is Completed.................................. 1-5
Microwave Measurement Procedure Canada........... 1-6
Microwave Measurement Procedure USA................ 1-7
Product Specification............................................ 1-8
Grounding Instructions......................................... 1-9
Electrical Requirements ........................................ 1-9
Oven Diagram...................................................... 1-10
Section 2 Operation
Operating Sequence Description............................ 2-1
Off Condition .................................................... 2-1
Cooking Condition............................................. 2-1
Oven Schematic-Off Condition............................... 2-2
Oven Schematic-Cooking Condition........................ 2-2
Ventilation Methods Hot Air Exhaust...................... 2-3
Power Level P-0 To P-90 Cooking.......................... 2-3
Power Output Reduction....................................... 2-3
Sensor Cooking Condition ..................................... 2-4
Cooking Sequence................................................ 2-4
Touch Control Panel Assembly Outline................... 2-5
Key Unit ........................................................... 2-5
Control Unit...................................................... 2-5
Component Descriptions....................................... 2-6
Door Open Mechanism ......................................... 2-6
Stop Switch (Door Sensing Switch), Primary
Interlock Switch And Third Door Switch ................. 2-6
Monitor Switch..................................................... 2-6
Thermal Cut-Out (Cavity)...................................... 2-6
Thermal Cut-Out (Hood)....................................... 2-7
Turntable Motor................................................... 2-7
Cooling Fan Motor................................................ 2-7
Hood Fan Motor................................................... 2-7
Hood Lamp.......................................................... 2-7
Stirrer Motor........................................................ 2-7
C/T Fuse.............................................................. 2-7
Humidity Sensor Circuit......................................... 2-8
Section 3 Troubleshooting and Testing
Warnings and Cautions......................................... 3-1
Troubleshooting Guide Chart................................. 3-2
Test Procedures................................................... 3-3
Section 4 Component Teardown
Warnings and Cautions......................................... 4-1
Hood Exhaust Louver Removal.............................. 4-2
Removal Of Oven From Wall ................................. 4-2
Outer Case Removal............................................. 4-2
Power Transformer Removal................................. 4-3
Hood Fan Motor, Hood Duct, Oven Lamp
Socket And AH Sensor Removal............................. 4-3
Magnetron Removal ............................................. 4-4
High Voltage Rectifi er And High Voltage
Capacitor Removal ............................................... 4-5
Turntable Motor Removal...................................... 4-5
Hood Fan Thermal Cut-Out Removal...................... 4-5
Thermal Cut-Out (Cavity) Removal........................ 4-6
Cooling Fan Motor Removal .................................. 4-6
Oven Lamp Removal ............................................ 4-7
Positive Lock® Connector (No-Case Type) ............ 4-7
Stirrer Motor Removal........................................... 4-8
Stirrer Cover And Stirrer Fan Removal.................... 4-8
Servicing The Touch Control Panel ....................... 4-8
Control Panel Assembly And Control Unit Removal.. 4-10
Graphic Sheet And Membrane Switch Replacement. 4-10
Stop Switch (Door Sensing Switch), Primary
Interlock Switch, Third Door Switch And Monitor
Switch Removal And Adjustment........................... 4-11
Door Replacement................................................ 4-12
Door Disassembly................................................. 4-13
Section 5 Wire Diagrams
Wiring Schematic Oven OFF Condition................... 5-1
Pictorial Component Diagram................................ 5-2
Wiring Diagram.................................................... 5-3
Control Board....................................................... 5-4
Section 6 Parts List
Control Panel Parts............................................... 6-1
Oven And Cabinet Parts List.................................. 6-2
Oven And Cabinet Parts Exploded View.................. 6-3
Door Parts For CGMV173KW & CGMV173KB........... 6-4
Door Parts For CGMV174KF................................... 6-5
Packing and Accessories Exploded View................. 6-6

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., 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.
Section 1 Basic Information
1-3
WARNING
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.
WARNING
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.
WARNING
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.

Section 1 Basic Information
1-4
Precautions To Be Observed Before And During Servicing To Avoid Possible Exposure To
Excessive Microwave Energy
1. Do not operate or allow the oven to be operated with the door open.
2. Make the following safety checks on all ovens to be serviced before activating the magnetron or other micro
wave 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.
3. 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.
4. 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.
5. 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 (Canadian Residents)
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 CANADA CORPORATION
immediately.
If the unit operates with the door open, service person should:
1. Tell the user not to operate the oven.
2. Contact ELECTROLUX CANADA CORPORATION and NHW, CANADA immediately.
Service personnel should inform ELECTROLUX CANADA CORPORATION 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.
NOTE: This section is required by DHHS because this microwave oven is imported by way of U.S.A.
Before Servicing (All Other Countries)
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.
Thiss section is required by DHHS because this microwave oven is imported by way of U.S.A.
NOTE

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.
WARNING
Section 1 Basic Information
1-5
Before Servicing
1. Disconnect the power supply cord, and thenremove
outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
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.
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.
4. Reconnect leads to the primary of the inverter unit.
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.
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) care-
fully 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.
Don't Touch!
Danger High
Voltage
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.
NOTE
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.
NOTE

Section 1 Basic Information
1-6
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/cm2with the test load of 275 ± 15 ml of water at an initial temperature 20 ±5°C.
2) 5.0 mW/cm2when 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/cm2without 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°±5°C (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 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.

Section 1 Basic Information
1-7
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/cm2at 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/cm2at 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/cm2at 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°±5°C (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.

Section 1 Basic Information
1-8
Product Specification
Item Description
Power Requirements 120 Volts / 14.0 Amperes
60 Hertz
Single phase, 3 wire grounded
Power Output 1000 watts (IEC 705 Test Procedure)
Operating frequency of 2450MHz
Case Dimensions (excluding handle) Width 29-15/16” Height 16-3/8” Depth 17-15/16”
Cooking Cavity Dimensions Width 21” NOTE: Internal capacity is calculated by measuring
(1.7 Cubic Feet ) Height 8-7/8 maximum width, depth and height. Actual
Depth 14-7/16” capacity for holding food is less.
Hood Lamp 20 Watt x 2 incandescent light bulbs
Oven Cavity Light 20 Watt x 1 incandescent light bulb
Weight Approx. Net 54 lbs. Gross 64 lbs.
Hood fan Approx. 300 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
Timer on-off pad, Turntable on-off pad, User Pref pad, Sensor Cook pad
Sensor Reheat pad, Auto Cook pad, Chicken nuggets pad, Snack Menu pad
Auto Defrost pad, Popcorn pad, Baked Potato pad, Vegetables pad,
Number pads, Quick start pads, START/Enter/+30sec pad, STOP/Clear pad
Power level pad, Light Hi/Lo/Off pad, Vent Hi/Lo/Off pad
Safety Standard NHW
FCC
DHHS, UL for use in USA or Canada

Section 1 Basic Information
1-9
3-Pronged Plug
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
Grounding Instructions
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.
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.
The receptacle should be located inside the cabinet
directly above the Microwave Oven/Hood system
mounting location.
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.
Improper use of the grounding plug can result in
a risk of electric shock.
WARNING

Section 1 Basic Information
1-10
1. Oven door with see-through window.
2. Door hinges.
3. Waveguide cover. DO NOT REMOVE.
4. Turntable motor shaft.
5. Oven lamp. It will light when oven is operating or
door is open.
6. Rack holders.
7. Safety door latches. The oven will not operate unless
the door is securely closed.
8. Handle.
9. Light hi/lo/off pad. Press light hi/lo/off pad once for
high, twice for low and three times to turn off light.
10. Vent hi/lo/off pad. Press the vent hi/lo/off pad once
for high speed, twice for low speed and three times
to turn off the fun.
11. Auto-Touch control panel.
12. Time display: Digital display, 99 minutes, 99
seconds.
13. Ventilation openings.
14. Removable turntable. The turntable will rotate
clockwise or counterclockwise. Only remove for
cleaning.
15. Removable turntable support. First, carefully place
the turntable support in the motor shaft in the
center of the microwave oven floor. Then, place
the turntable on the turntable support securely.
16. Rack for 2-level cooking/ reheating.
17. Light cover.
18. Grease filters
Oven Diagram
(Front of microwave oven)
(Rear of microwave oven)
BOTTOM VIEW
FRONT VIEW
1
2
3
4
5
66
77
8910
11
12
13
14
15 16
17
18
19

Section 2 Operation
2-1
The following is a description of component functions
during oven operation.
OFF CONDITION
Closing the door activates the stop switch (door sensing
switch) secondary interlock switch and third door
switch. (In this condition, the monitor switch contacts
are opened.) When oven is plugged in, 120 volts AC is
supplied to the control unit. (Figure 2-1).
1. The display will show “ENJOY YOUR OVEN PRESS
CLEAR”. To set any program or set the clock, you
must first touch the CLEAR/OFF pad. The display
will clear, and “ : “ appears.
COOKING CONDITION
Program desired cooking time touching the NUMBER
pads. When the START pad 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 / Fan motor / Stirrer motor
RY2 Power Transformer
RY7 Turntable motor
2. 120 volts AC is supplied to the primary winding of
the power transformer and is converted to about
3.3 volts AC output on the filament winding, and
approximately 2000 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.
6. When the door is opened during a cook cycle,
monitor switch, door sensing switch, primary
interlock switch, third door switch and secondary
interlock relay are activated with the following
results. The circuits to the stirrer motor, the cooling
fan motor, the turntable motor, and the high voltage
components are de-energized, 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 primary interlock switch, and stop
switch (door sensing switch) 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 secondary interlock relay, stop switch (door
sensing switch) and primary interlock switch and
third door 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 primary interlock switch, stop
switch (door sensing switch) and third door
switch close. And contacts of the relay (RY1)
open.
If the primary interlock switch fails with the contacts
closed when the door is opened, the closing of the
monitor switch contacts will form a short circuit through
the C/T fuse, primary interlock switch and relay (RY1)
causing the C/T fuse to blow.
Operating Sequence Description

Section 2 Operation
2-2
Figure 2-1. Oven Off Condition
Figure 2-2. Oven ON (Cooking) Condition

Section 2 Operation
2-3
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the
120 volts A.C. 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) 32 sec. 0 sec.
Power 9 (P-90) (Approx. 90%) 30 sec. 2 sec.
Power 8 (P-80) (Approx. 80%) 26 sec. 6 sec.
Power 7 (P-70) (Approx. 70%) 24 sec. 8 sec.
Power 6 (P-60) (Approx. 60%) 22 sec. 10 sec.
Power 5 (P-50) (Approx. 50%) 18 sec. 14 sec.
Power 4 (P-40) (Approx. 40%) 16 sec. 16 sec.
Power 3 (P-30) (Approx. 30%) 12 sec. 20 sec.
Power 2 (P-20) (Approx. 20%) 8 sec. 24 sec.
Power 1 (P-10) (Approx. 10%) 6 sec. 26 sec.
Power 0 (P-0) (0% power) 0 sec. 32 sec.
POWER OUTPUT REDUCTION
If the oven is set for over 40 minutes at 80%, 90% or
100% power level, after the first 40 minutes the power
level will automatically adjust itself to 70% power to
avoid overcooking.
The ON/OFF time ratio does not correspond with
the percentage of microwave power, because
approximately 2 seconds are needed for heating of
the magnetron filament.
NOTE
VENTILATION METHODS HOT AIR EXHAUST
1. Vertical Venting
For this venting method, hot air rising from the
conventional range below is drawn in by the hood fan
motor through the grease filters at the right and left
sides of the base cover, up through the right and left
sides of the oven cavity, then discharged vertically at rear
center top of the oven, into the customer’s vent system.
2. Horizontal Venting
The air handing is the same as Vertical Venting except
that final air discharge is directed horizontally out from
the top rear of oven into the customer’s vent system.
3. Re-circulation (Inside venting)
The air handing is the same as VERTICAL VENTING
except that the final air discharge is directed horizontally
through the upper front of the oven into the kitchen.
Air Flow
To Duct To Duct
Hood Fan Motor
Hood
Intake
Duct
Grease
Filter
Air Flow
To Duct
Hood Fan Motor
Hood
Intake
Duct
Grease
Filter
Air Flow
Hood Fan Motor
Hood
Intake
Duct
Hood Exhaust
Louver Charcoal
Filter

Section 2 Operation
2-4
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. Heat Potatoes. Moisture and humidity is emitted
rapidly. You can smell the aroma as it cooks.
3. Sensor detects moisture and humidity and
calculates cooking time and variable power.
MICROWAVE
MICROWAVE
AH SENSOR
COOKING SEQUENCE
1. Operate the oven in sensor cooking mode by
referring to the operation manual.
2. The coil of shut-off relays (RY1) are energized, the
oven lamp, stirrer motor and cooling fan motor are
turned on, but the power transformer is not turned
on.
3. After about 32 seconds, the relay (RY2) is energized.
The power transformer is turned on, microwave
energy is produced and first stage is started.
The 32 seconds is the cooling time required to
remove any vapor from the oven cavity and sensor.
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.
The oven should not be operated on SENSOR
immediately after plugging in the unit. Wait two minutes
before cooking on SENSOR.
NOTE
During this first stage, do not open the door or touch
STOP/CLEAR pad.
NOTE

Section 2 Operation
2-5
Touch Control Panel Assembly Outline
The touch control section consists of the following units.
(1) Key unit
(2) Control Unit
The principal functions of these units and the signals
communicated among them are explained below.
KEY UNIT
The key unit is composed of a matrix, signals generated
in the LSI are sent to the key unit through P40 - P47.
When a key pad is touched, a signal is completed
through the key unit and passed back to the LSI through
P20, P21, P22, P00 and P01 to perform the function that
was requested.
CONTROL UNIT
Control unit consists of LSI, power source circuit,
synchronizing signal circuit, reset circuit, buzzer circuit,
relay circuit indicator circuit, humidity sensor circuit and
back light circuit.
1. LSI
This LSI controls the key strobe signal, relay driving
signal for oven function and indicator signal.
2. Power Source Circuit
This circuit generates voltages necessary for the
control unit from the AC line voltage. In addition,
the synchronizing signal is available in order to
compose a basic standard time in the clock circuit.
Symbol Voltage Application
VC -5.0V LSI(IC1)
3. Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit. It incorporates a very small error because it
works on commercial frequency.
4. Reset Circuit
This circuit generates a signal which resets the LSI
to the initial state when power is supplied.
5. Buzzer Circuit
The buzzer responds to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
6. Stop Switch (Door Sensing Switch)
A switch to inform the LSI if the door is open or
closed.
7. Relay Circuit
To drive the magnetron, fan motor, turntable motor,
stirrer motor, hood motor, and light the oven lamp
and hood lamp.
8. Indicator Circuit
This circuit consists of 25 segments and 4 common
electrodes using a Light Crystal Display.
9. Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1-LD5).
10. Humidity Sensor Circuit
This circuit detects moisture of the cooking food to
allow its automatic cooking.

Section 2 Operation
2-6
MONITOR SWITCH
The monitor switch is activated (the contacts opened)
by the latch head on the door while the door is closed.
The switch is intended to render the oven inoperative,
by means of blowing the C/T fuse, when the contacts of
the primary interlock switch fail to open when the door is
opened.
Functions:
1. When the door is opened, the monitor switch con-
tacts close (to the ON condition) due to their being
normally closed. At this time the primary interlock
switch is in the OFF condition (contacts open) due
to its being normally open contact switches. And
the contacts of relay (RY-1) are in the ON condition
(contacts close).
2. As the door goes to a closed position, the monitor
switch contacts are first opened and the primary
interlock switch contacts close. Contacts of the relay
(RY-1) are in the OFF condition. (On opening the
door, each of these switches operate inversely.)
3. If the door is opened and the primary interlock
switch contacts fail to open, the C/T fuse blows
simultaneously with closing of the monitor switch
contacts.
THERMAL CUT-OUT (CAVITY)
This thermal cut-out is located on the top of the oven
cavity. It is designed to prevent damage to the oven unit
if the food in the oven catches fire due to overheating
produced by improper setting of cooking time or failure
of control unit. Under normal operation, the thermal
cut-out remains closed. However, the thermal cut-out will
open at 293°F (145°C) causing the oven to shut down.
Before replacing a blown C/T fuse test the stop
switch (door sensing switch), relay (RY1),
primary interlock switch, third door switch and
monitor switch components for proper
operation.
CAUTION
C/T fuse and monitor switch are replaced as an
assembly.
NOTE
DOOR OPEN MECHANISM
The door is opened by pulling the door handle, refer to
the Figure 2-3.
STOP SWITCH (DOOR SENSING SWITCH),
PRIMARY INTERLOCK SWITCH AND THIRD DOOR
SWITCH
The primary interlock switch is mounted in the lower
position of the latch hook, the stop switch (door sensing
switch) in the secondary interlock system is mounted
in the upper position of the latch hook. The third door
switch is mounted in the upper vertical position of the
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 secondary interlock system
consists of the door sensing switch and secondary
interlock relay located on the control circuit board.
Figure 2-3. Door Open Mechanism
Component Descriptions
Primary
Interlock
Switch
Monitor
Switch
Latch
Hook
Door
Latch
Heads Stop
Switch
(Door
Sensing
Switch)
Third Door
Switch

Section 2 Operation
2-7
THERMAL CUT-OUT (HOOD )
This thermal cut-out is located on the right base plate. It
is designed to automatically turn on the hood fan motor
whenever the hot air rising from the conventional range
below causes the temperature at the thermal cut-out to
rise to 140°F (60°C) or higher, thus removing this hot
air from around microwave oven. When the temperature
around the thermal cut-out drops to 113°F (45°C) or
lower, the thermal cut-out shuts off the hood fan motor.
TURNTABLE MOTOR
The turntable motor rotates the turntable located on
the bottom of the oven cavity, so that the foods on the
turntable cook evenly during cooking. Turntable will turn
in either direction. The turntable motor can be turned off
by touching TURNTABLE ON/OFF pad.
COOLING FAN MOTOR
The cooling fan motor drives a blade which draws
external cool air. This cool air is directed through the
air vanes surrounding the magnetron and cools the
magnetron. This air is channelled through the oven
cavity to remove steam and vapors given off from the
heating foods. It is then exhausted through exhausting
air vents at the oven cavity.
HOOD FAN MOTOR
The hood fan motor is a two-speeds, single-phase,
double pole induction type, requiring a hood fan
capacitor. It is located outside the upper rear part of
the oven cavity. The hood fan motor removes hot air
from around the oven as it rises from the conventional
electric or gas range over which it is installed. This air is
then expelled either vertically or horizontally through the
customer supplied duct system, or discharged back into
the kitchen.
HOOD LAMP
The hood lamps are mounted at the hood lamp angle on
the base cover. The hood lamps can be turned off and
on by touching the Light HI/LO/OFF pad. The brightness
can be varied to high or low by touching the Light HI/LO/
OFF pad.
STIRRER MOTOR
The stirrer motor drives the stirrer fan to stir the
microwave radiation from the waveguide.
C/T FUSE
1. The C/T fuse blows when the contacts (COM-NO) of
the primary interlock switch remain closed with the
oven door open and when the monitor switch closes.
2. If the wire harness or electrical components are
short-circuited, this C/T fuse blows to prevent an
electric shock or fire hazard.
3. The C/T fuse, located near the magnetron, 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., the C/T fuse will open.
Under normal operation, the C/T fuse remains closed.
However, when abnormally high temperatures are
reached within the oven cavity, the C/T fuse will open at
302°F (150°C), causing the oven to shut down or when
the electric current is beyond 20 Amp flow, the C/T fuse
will open.

Section 2 Operation
2-8
HUMIDITY SENSOR CIRCUIT
1. Structure of Absolute Humidity Sensor:
The absolute humidity sensor includes two
thermistors as shown in the illustration below. One
thermistor is housed in the closed vessel filled with
dry air while another in is the open vessel. Each
sensor is provided with the protective cover made of
metal mesh to be protected from the external
airflow.
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.
Ventilation opening for sensing Sensing part
(Open vessel) Sensing part (Closed vessel)
Thermistors
C
S
R3
R1
R2
+
-
Operational
amplifier Output
voltage
S :Thermistor
open vessel
C :Thermistor
closed vessel
2
Humidity (g/m )
Outputvoltage
humidity vs, output voltage
characteristic
Figure 2-5. Humidity Sensor Operation
Figure 2-4. Humidity Sensor Diagram
(3) Detector Circuit of Absolute Humidity Sensor
Circuit:
This detector circuit is used to detect the output
voltage of the humidity circuit to allow the LSI to
control sensor cooking of the unit. When the unit is
set in the sensor cooking mode, 32 seconds clearing
cycle occurs than the detector circuit starts to
function and the LSI observes the initial voltage
available at its AIN4 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 R98 ~ R102 of IC2. Changing
the resistance values results in that there is the
same potential at both F-3 terminals of the humidity
sensor and AIN6 terminal of the LSI. The voltage of
AIN4 terminal will indicate about -2.5V. This initial
balancing is set up about 32 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 the bridge
circuit is deviated to increase the voltage available
at AIN4 terminal of the LSI. Then the LSI observes
that voltage at AIN4 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 AIN4 terminal 32 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 humidity sensor,
ERROR will appear on the display and the cooking is
stopped.
Humidity sensor circuit:
SW1
SW2
SW3
SW4
SW5
P50
P51
P52
P53
P54
LSI
(IC1)
AIN6
AIN4
620k
300k
150k
75k
37.4k
40
43
44
21
19
42
41
47k
47k
10k
0.01uF
0.015uF
0.01uF
VA : -15V VA : -15V
R90
C90
C91
C93
C92
S
F-2 1.8k
F-1
F-3C3.57k
3.32k
VC : -5V
0.1
uF
C. Thermistor in
closed vessel
S. Thermistor in
open vessel
R98
R99
R96
R91
360k
R93
R92
R94 R95
D90
R100
R101
R102
R97
IC 2
+
-