SHARP R203CW2, R-203CW Service Manual
SER VICE MANU AL
S2902R203CPW/
MICROWAVE OVEN
R-203CW
ON
DEF. LBS. QTY.
CHECK
1. Ground meat
2. Steaks/chops
3. Chicken pieces
COMPU DEFROST
To adjust quantity-touch pad again
SNACKS
POPCORN
BEVERAGE
COOKING
BAKED
FRESH
POTATO
VEGETABLES
REHEATING
DINNER
ROLL,
PLATE
MUFFIN
123
456
78
Power
Level
Timer
0
Clock
Stop
START
Clear
Minute Plus
9
MODEL
In the interest of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
WARNING TO SERVICE PERSONNEL: Microwave ovens contain circuitry capable of producing very high voltage and
R-203CW
current, contact with following parts may result in a severe,
possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc..)
TABLE OF CONTENTS
Page
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ...................INSIDE FRONT COVER
BEFORE SERVICING ......................................................................................................INSIDE FRONT COVER
WARNING TO SERVICE PERSONNEL................................................................................................................1
MICROWAVE MEASUREMENT PROCEDURE ...................................................................................................2
FOREWORD AND WARNING...............................................................................................................................3
PRODUCT SPECIFICATIONS ..............................................................................................................................4
GENERAL INFORMATION...................................................................................................................................4
OPERATION..........................................................................................................................................................6
TROUBLESHOOTING GUIDE ..............................................................................................................................8
TEST PROCEDURE ............................................................................................................................................10
TOUCH CONTROL PANEL .................................................................................................................................17
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................21
PICTORIAL DIAGRAM ........................................................................................................................................27
CONTROL PANEL CIRCUIT ...............................................................................................................................28
PRINTED WIRING BOARD .................................................................................................................................29
PARTS LIST ........................................................................................................................................................30
PACKING AND ACCESSORIES .........................................................................................................................34
SHARP CORPORATION
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-203CW
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 SHARP ELECTRONICS
CORPORATION immediately @1-800-237-4277.
If the unit operates with the door open, service person should 1) tell the user not to operate the oven
and 2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's
Center for Devices and Radiological Health immediately.
Service personnel should inform SHARP ELECTRONICS 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.
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with
following parts
fatal, electrical shock.
(Example)
High Voltage Capacitor, High Voltage Power Trans-
former, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc..
Read the Service Manual carefully and follow all
instructions.
may result in a severe, possibly
R-203CW
Don't Touch !
Danger High Voltage
Before Servicing
1. Disconnect the power supply cord , and then
remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
WARNING:RISK OF ELECTRIC SHOCK.
DISCHARGE THE HIGH-VOLTAGE
CAPACITOR BEFORE SERVICING.
The high-voltage capacitor remains charged about 60
seconds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the highvoltage capacitor (that is the connecting lead of the highvoltage 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 power supply cord, and then remove
outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
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. Discharge high voltage capacitor.
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.
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 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 reexamine 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.
1
R-203CW
MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
should not exceed 1mW/cm2 at any point 5cm 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 5cm or more from the external
surface of the oven.
2) Safety interlock switches Primary interlock relay and door sensing 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 5cm 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 4mW/cm2,
and that the secondary interlock switch does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
2
SERVICE MANUAL
MICROWAVE OVEN
R-203CW
PRODUCT DESCRIPTION
R-203CW
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP MICROWAVE OVEN, R-203CW.
It is recommended that service personnel carefully study the entire
text of this manual so that they will be qualified to render satisfactory
customer service.
Check the interlock switches and the door seal carefully. Special
attention should be given to avoid electrical shock and microwave
radiation hazard.
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.
DANGER
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;
High Voltage Capacitor, Power Transformer, Magnetron, High
Voltage Rectifier Assembly, High Voltage Harness;
If provided, Vent Hood, Fan assembly, Cooling Fan Motor.
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST
All the parts marked “*” on parts list are used at voltages more than
250V.
Removal of the outer wrap gives access to voltage above 250V.
All the parts marked “∆” on parts list may cause undue microwave
exposure, by themselves, or when they are damaged, loosened
or removed.
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
3
R-203CW
PRODUCT DESCRIPTION
SPECIFICATIONS
ITEM DESCRIPTION
Power Requirements 120 Volts
60 Hertz
Single phase, 3 wire grounded
Power Consumption 1100W / Approx. 9.5 Amperes
Power Output 700 W nominal of RF microwave energy (IEC 705 Test procedure)
Operating frequency 2450 MHz
Case Dimensions Width 18-1/8"
Height 11-3/8"
Depth 14-5/8"
Cooking Cavity Dimensions Width 12-3/8"
(0.7 Cubic feet) Height 7-7/8"
Depth 12-5/8"
Control Complement Touch Control System
Clock (1:00 - 12:59)
Timer (0 - 99 minutes 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
COMPU DEFROST pad
Instant Start pads
Number selection pads
Timer/Clock pad
Power Level pad
START/ Minute plus pad
Stop/Clear pad
Oven Cavity Light Yes
Safety Standard UL Listed.
FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
GENERAL INFORMATION
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 and 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.
WARNING: Improper use of the grounding plug can result in a risk of electric shock.
4
R-203CW
1. Ground meat
2. Steaks/chops
3. Chicken pieces
To adjust quantity-touch pad again
COMPU DEFROST
POPCORN
BEVERAGE
BAKED
POTATO
DINNER
PLATE
Power
Level
Timer
Clock
Stop
Clear
START
Minute Plus
ROLL,
MUFFIN
FRESH
VEGETABLES
SNACKS
COOKING
REHEATING
123
456
78
0
9
DEF. LBS. QTY.
CHECK
ON
Time display
Indicator
Electrical Requirements
The electrical requirements are a 115 -120 volt 60 Hz, AC only,
15 or 20 amp. fused electrical supply. It is recommended that a separate
circuit serving only this appliance be provided. 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 the extension cord must be used, it should be a 3-wire, 15
amp. or higher rated cord. Do not drape over a countertop or table where
it can be pulled on by children or tripped over accidentally.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING PRONG FROM
THIS PLUG.
3-Pronged Plug
Grounding Pin
3-Pronged Receptacle
Grounded
Receptacle Box
OVEN DIAGRAM
8
9
3
2
1. Oven door with see-through window
2. Safety door latches.
3. Door hinges
4. Door seals and sealing surfaces
5. Turntable motor shaft
6. Removable turntable support
7. Removable turntable
8. Ventilation openings. (Rear)
9. Oven lamp.
10.Wave guide cover.
11.Power supply cord
1
4
5
10
11
TOUCH CONTROL PANEL
7
6
5
R-203CW
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during
oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and
secondary interlock switch. (In this condition, the monitor
switch contacts are opened.)
When the oven is plugged in, 120 volts A.C. is supplied to
the control unit. (Figure O-1).
1. The display will show flashing "88:88".
To set any program or set the clock, you must first touch
the STOP/CLEAR pad. The display will clear, and " : "
will appear.
COOKING CONDITION
Program desired cooking time by touching the NUMBER
pads. And program the power level by touching the POWER
LEVEL pad and then a Number pad.
When the START pad is touched, the following operations
occur:
1. The contacts of the relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure O-2)
RELAY CONNECTED COMPONENTS
RY-1 oven lamp/turntable motor/fan motor
RY-2 power transformer
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3.5 volts
A.C. output on the filament winding, and approximately
2000 volts A.C. 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
channelled 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, the
monitor switch, door sensing switch, secondary interlock
switch and primary interlock relay are activated with the
following results. The circuits to the oven lamp, turntable
motor, the cooling fan 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 secondary interlock switch and primary interlock
relay (RY2) and is mechanically associated with the door
so that it will function in the following sequence.
(1) When the door opens from the closed position, the
secondary interlock switch, door sensing switch and
primary interlock relay (RY2) open their contacts. 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 the secondary interlock switch and primary interlock relay
(RY2) fail 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 and primary interlock relay
(RY2), causing the C/T fuse to blow.
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 (RY-2) which is operated by the
control unit within a 32 second time base. Microwave power
operation is as follows:
VARI-MODE ON TIME OFF TIME
Power 10(P-HI) 32 sec. 0 sec.
(100% power)
Power 9(P-90) 30 sec. 2 sec.
(approx. 90% power)
Power 8(P-80) 26 sec. 6 sec.
(approx. 80% power)
Power 7(P-70) 24 sec. 8 sec.
(approx. 70% power)
Power 6(P-60) 22 sec. 10 sec.
(approx. 60% power)
Power 5(P-50) 18 sec. 14 sec.
(approx. 50% power)
Power 4(P-40) 16 sec. 16 sec.
(approx. 40% power)
Power 3(P-30) 12 sec. 20 sec.
(approx. 30% power)
Power 2(P-20) 8 sec. 24 sec.
(approx. 20% power)
Power 1(P-10) 6 sec. 26 sec.
(approx. 10% power)
Power 0(P-0) 0 sec. 32 sec.
(0% power)
Note: 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.
6
R-203CW
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. CLOCK APPEARS ON DISPLAY
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. COOKING TIME PROGRAMMED
3. VARIABLE COOKING CONTROL
"HIGH"
4. "START" PAD TOUCHED
120V AC
60 Hz
C/T FUSE
A3
CONTROL UNIT
GRN
OL FM
OVEN
LAMP
SECONDARY
INTERLOCK
SWITCH
Figure O-1. Oven Schematic-Off Condition
C/T FUSE
A3
MAGNETRON
THERMAL CUT-OUT
(RY-1)
A1
TTM
TURN-
TABLE
MOTOR
MAGNETRON
THERMAL CUT-OUT
(RY-1)
COM.
(RY-2)
B1 B2
FAN
MOTOR
COM.
(RY-2)
PRIMARY
INTERLOCK
RELAY
DOOR
SENSING
SWITCH
PRIMARY
INTERLOCK
RELAY
N.O.
N.O.
MONITOR
SWITCH
POWER
TRANSFORMER
POWER
TRANSFORMER
CAPACITOR
0.86µF
RECTIFIER
MAGNETRON
CONTROL UNIT
120V AC
60 Hz
GRN
OL FM
OVEN
LAMP
SECONDARY
INTERLOCK
SWITCH
Figure O-2. Oven Schematic-Cooking Condition
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pulling the door, refer to the Figure
D-1.
Latch Heads
Door
Secondary
Interlock
Switch
Figure D-1. Door Open Mechanism
Latch Hook
Door
Sensing
Switch
Monitor
Switch
CAPACITOR
0.86µF
RECTIFIER
MAGNETRON
TTM
TURN-
TABLE
MOTOR
A1
B1 B2
FAN
MOTOR
DOOR
SENSING
SWITCH
MONITOR
SWITCH
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the lower
position of the latch hook and the door sensing switch in the
primary interlock system is mounted in the upper position of
the latch hook. They are activated by the latch heads on the
door. When the door is opened, the switches interrupt the
power to all high voltage components. A cook cycle cannot
take place until the door is firmly closed thereby activating
both interlock switches. The primary interlock system consists of the door sensing switch and primary interlock relay
located on the control circuit board.
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
7
R-203CW
blowing the C/T fuse, when the contacts of the primary
interlock relay (RY2) and secondary interlock switch fail to
open when the door is opened.
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 primary interlock relay (RY2) and
secondary interlock switch are in the OFF condition
(contacts open) due to its 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 and secondary interlock switch contacts close.
3. If the door is opened, and the primary interlock relay
(RY2) and the secondary interlock switch contact fail to
open, the C/T fuse blows simultaneously with closing of
the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN C/T FUSE,
TEST THE DOOR SENSING SWITCH, PRIMARY INTERLOCK RELAY (RY2), SECONDARY INTERLOCK SWITCH AND MONITOR
SWITCH FOR PROPER OPERATION. (REFER TO CHAPTER "TEST PROCEDURE").
NOTE: C/T FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY
TURNTABLE MOTOR
The turntable motor rotates the turntable located on the
bottom of the oven cavity, so that the food on the turntable
is cooked evenly. The turntable may turn in either direction.
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 vapours given off from the heating foods. It is then
exhausted through the exhausting air vents at the oven
cavity.
MAGNETRON THERMAL CUT-OUT
The thermal cut-out located on the top of the oven cavity is
designed to prevent damage to the magnetron if an over
heated condition develops in the tube 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.
C/T FUSE
1. The C/T fuse blows when the contacts (COM-NO) of the
primary interlock relay (RY2) and secondary interlock
switch remain closed with the oven door open and when
the monitor switch closes.
2. If the wire harness or electrical components are shortcircuited, this C/T fuse blows to prevent an electric shock
or fire hazard.
3. The C/T fuse, located on the top of the oven cavity, is
designed to prevent damage to the oven by fire. If the
food load is overcooked, by either error in cook time or
defect in the timer, 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 248˚F
(120˚C), causing the oven to shut down or when the electric
currents beyond 13A flow, the C/T fuse will open.
TROUBLESHOOTING GUIDE
Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.
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.
IMPORTANT: If the oven becomes inoperative because of a blown C/T fuse, check the monitor switch, primary
interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the C/T fuse.
If the C/T fuse is replaced, the monitor switch must also be replaced. Use part FFS-BA020WRK0 as an
assembly.
IMPORTANT: 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. Discharge high voltage capacitor.
8
4. Disconnect the leads to the primary of the power transformer.
5. sge 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. Discharge high voltage capacitor.
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.
CK = Check / RE = Replace
TEST PROCEDURE
RE CK AB C
D
EFFGHRE RE CK
I/K
CK CKCK J L M
R-203CW
CONDITION
OFF
CONDITION
COOKING
CONDITION
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
PROBLEM
Home fuse blows when power cord
is plugged into wall receptacle.
C/T fuse blows when power cord is
plugged into wall receptacle.
All letters and indicators do not appear in display when power cord is
first plugged into wall outlet.
Display does not operate properly
when STOP/CLEAR key is touched.
(Buzzer should sound and time of
day should appear in display.)
C/T fuse blows when the door is
opened.
Fan motor does not operate. (All
other electric components function.)
Oven lamp does not light at all. (All
other electric components function.)
Turntable motor does not operate. (All
other electric components function.)
Oven does not go into cook cycle
when START pad is touched
Oven seems to be operating but little
or no heat is produced in oven load.
(Food incompletely cooked or not
cooked at all at end of cook cycle.)
Oven goes into a cook cycle but
extremely uneven heating is produced in oven load (food).
Oven does not cook properly when
programmed for Cooking Power 5
mode. (Operates properly on Cooking Power 10 (HIGH) mode.)
Oven lamp, turntable motor and fan
motor do not operate.
Oven goes into EXPRESS DEFROST
but food is not defrosted well.
SHORT IN POWER CORD
SHORT OR OPEN WIRING
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
MAGNETRON THERMAL CUT-OUT
PRIMARY INTERLOCK SYSTEM
SECONDARY INTERLOCK SWITCH
MONITOR SWITCH
C/T FUSE
OVEN LAMP OR SOCKET
COOLING FAN MOTOR
TURNTABLE MOTOR
CONTROL UNIT OR RELAY
WRONG OPERATION
LOW VOLTAGE
DIRTY OVEN CAVITY
KEY UNIT
EXPRESS DEFROST
FOIL PATTERN ON PWB.
9
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