Sharp R-21JCA-F User manual

R-21JCA-F
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 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 .............................................................................................................................. 9
TEST PROCEDURE ............................................................................................................................................ 10
TOUCH CONTROL PANEL ................................................................................................................................. 16
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................ 20
PICTORIAL DIAGRAM ........................................................................................................................................ 27
CONTROL PANEL CIRCUIT .............................................................................................................................. 28
PRINTED WIRING BOARD ................................................................................................................................. 29
PARTS LIST ........................................................................................................................................................ 30
PACKING AND ACCESSORIES ......................................................................................................................... 34
S0514R21JCPAF
R-21JCA-F
LIGHT DUTY
COMMERCIAL
MICROWAVE OVENS
MODEL
SERVICE MANUAL
SHARP CORPORATION
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
1000W/ R-21JCA
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TIME GUIDE FOR ONE SERVING
15 - 30 sec.
Bagel, Roll
Muffin, Pastry
Pie Slice
30 - 60 sec.
Hot Dog
Pizza Slice
Small Sandwich
1 - 2 min.
Beverage, Soup
Large Sandwich
Popcorn, 1.5 oz.
2 - 3 min.
Casserole, Stew
Chili, Chowder
Popcorn, 3.5 oz.
With the door closed,turn the timer to
the desired time. Oven will begin
operating immediately.
To shut oven off manually,return timer
to "0".
INSTRUCTIONS
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R-21JCA-F
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 oven 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 the 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.

R-21JCA-F
1
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of pro-
ducing very high voltage and current, contact with
following parts
may result in a severe, possibly
fatal, electrical shock.
(Example)
High Voltage Capacitor, High Voltage Power Trans-
former, Magnetron, High Voltage Rectifier Assem-
bly, High Voltage Harness etc..
Read the Service Manual carefully and follow all
instructions.
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 sec-
onds after the oven has been switched off. 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 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 re-examine the connec-
tions 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 microwave leakage test should be carried out.
Don't Touch !
Danger High Voltage

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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/cm2at 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/cm2at 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/cm2at 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.

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SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
SERVICE MANUAL
LIGHT DUTY
COMMERCIAL
MICROWAVE OVEN
R-21JCA-F
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the SHARP
MICROWAVE OVENS, R-21JCA-F.
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 person-
nel - 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.
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.
PRODUCT DESCRIPTION
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST

R-21JCA-F
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3-Pronged Plug Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
ITEM DESCRIPTION
Power Requirements 120 Volts
14 Amperes
60 Hertz / Single phase, 3 wire grounded
Power Output 1000 watts (IEC 705 Test Procedure)
Operating frequency of 2450MHz
Case Dimensions Width 20-1/2" (520mm)
Height 12-1/8" (309mm)
Depth 16" (406mm)
Cooking Cavity Dimensions Width 13-7/8" (353mm)
(1.0 Cubic Feet ) Height 8-1/8" (207mm)
Depth 14-5/8"(370mm)
Control Complement Light Up Dial (6 minutes)
No cooking control
Oven Cavity Light Yes
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J, NSF Certified
SPECIFICATION
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.
Electrical Requirements
The electrical requirements are a 120 volt 60 Hz, AC only,
15 amp. or more protected 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.
NOTE: Internal capacity is calculated by measuring
maximum width, depth and height.
Actual capacity for holding food is less.

R-21JCA-F
5
OVEN DIAGRAM
1. Back splash cover
2. Side splash cover
3. Oven light
4. Ceramic shelf
5. Control panel
6. Cavity face plate
7. Door latch openings
8. Door latches
9. Door hinges
10.Door seals and sealing surfaces
11.Door handle
12.Oven door with see-through
window
13.Air ventilation cover and openings
14.Power supply cord
15.Air intake openings
16.Outer case cabinet
114 13 912
11
76 5
15
16
10
3 2
4
8
CONTROL PANEL
TIME GUIDE FOR ONE SERVING
15 - 30 sec.
Bagel, Roll
Muffin, Pastry
Pie Slice
30 - 60 sec.
Hot Dog
Pizza Slice
Small Sandwich
1 - 2 min.
Beverage, Soup
Large Sandwich
Popcorn, 1.5 oz.
2 - 3 min.
Casserole, Stew
Chili, Chowder
Popcorn, 3.5 oz.
With the door closed,turn the timer to
the desired time. Oven will begin
operating immediately.
To shut oven off manually,return timer
to "0".
INSTRUCTIONS
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Light Up Dial for setting cooking time.

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OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during
oven operation.
OFF CONDITION
Closing the door activates door sensing switch and secondary
interlock switch. (In this condition, the monitor switch contacts
are opened.)
When oven is plugged in, 120 volts A.C. is supplied to the noise
filter and the control unit (Figure O-1).
COOKING CONDITION
When the Light Up Dial is turned, 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 O-2)
RELAY CONNECTED COMPONENTS
RY-1 Oven lamp/ Antenna 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 3.2 volts A.C.
output on the filament winding, and approximately 2150
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 feed-box,
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, secondary interlock switch,
relay (RY2) and primary interlock relay(RY1) are activated
with the following results. The circuits to the antenna motor,
the cooling fan motor, the oven lamp and the high voltage
components are de-energized, and the cooking program
will be canceled when the door was opened.
7. The monitor switch electrically monitors the operation of the
secondary interlock switch and primary interlock relay(RY1)
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 primary
interlock relay(RY1) and secondary interlock switch 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 (RY1) fail
with the contacts closed when the door is opened, the closing of the
monitor switch contacts will form a short circuit through the monitor
fuse, secondary interlock switch, and primary interlock relay(RY1),
causing the monitor fuse to blow.

R-21JCA-F
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Figure O-2 Oven Schematic-Microwave cooking Condition
NOTE: Indicates components with potential above 250 V.
Figure O-1 Oven Schematic-OFF Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. LIGHT UP DIAL OFF.
2. DOOR CLOSED.
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. LIGHT UP DIAL ON.
FUSE
LINE CROSS CAPACITOR 0.22 F AC250V
NOISE SUPPRESSION COIL
LINE BYPASS
CAPACITOR
0.003300 F / AC 125V
LINE BYPASS
CAPACITOR
0.003300 F / AC 125V
20A
NOISE FILTER
NL
AC120V
60 Hz
OL FM AM
OVEN
LAMP
FAN
MOTOR
ANTENNA
MOTOR
POWER
TRANSFORMER
CAPACITOR
0.94 µF
2400V
DOOR SENSING
SWITCH
SECONDARY
INTERLOCK SWITCH
CONTROL UNIT
THERMAL
CUT-OUT
125˚C (OVEN)
THERMAL
CUT-OUT
145˚C (MAG.)
PRIMARY INTERLOCK RELAY
COOK RELAY
MONITOR SWITCH
MAGNETRON
RECTIFIER
RY1 RY2
A5
A3 A1
FUSE
LINE CROSS CAPACITOR 0.22 F AC250V
NOISE SUPPRESSION COIL
LINE BYPASS
CAPACITOR
0.003300 F / AC 125V
LINE BYPASS
CAPACITOR
0.003300 F / AC 125V
20A
NOISE FILTER
NL
AC120V
60 Hz
OL FM AM
OVEN
LAMP
FAN
MOTOR
ANTENNA
MOTOR
POWER
TRANSFORMER
CAPACITOR
0.94 µF
2400V
DOOR SENSING
SWITCH
SECONDARY
INTERLOCK SWITCH
CONTROL UNIT
THERMAL
CUT-OUT
125˚C (OVEN)
THERMAL
CUT-OUT
145˚C (MAG.)
PRIMARY INTERLOCK RELAY
COOK RELAY
MONITOR SWITCH
MAGNETRON
RECTIFIER
RY1 RY2
A5
A3 A1

R-21JCA-F
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DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by grasping the door handle, refer to Figure
D-1.
When the door handle is grasped, the handle lever is pulled.
And then the upper and lower latch heads are moved upward
by the handle lever, and they are released from the latch
hook. Now the door will open.
Figure D-1. Door Open Mechanism
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the upper posi-
tion of the latch hook and the door sensing switch in the primary
interlock system is mounted in the lower position of the latch
hook. The secondary interlock switch is activated by the latch
switch lever A. The latch switch lever A is activated by the upper
latch head. The door sensing switch is activated by the latch
switch lever C. The latch switch lever C is activated by the lower
latch head. 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 switch lever B on the latch hook while the door is closed.
The latch switch lever B is activated by the lower latch head.
The switch is intended to render the oven inoperative, by
means of blowing the monitor fuse, when the contacts of the
primary interlock relay (RY1) 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 (RY1) and
secondary interlock switch 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
and the secondary interlock switch contacts close. (On
opening the door, each of these switches operate inversely.)
3. If the door is opened, and the primary interlock relay (RY1)
Latch Hook
Latch Switch
Lever A
Latch Switch
Lever B
Latch Switch
Lever C
Latch Head
Latch Head
Handle
Lever
Door
Handle
Latch
Lever
Secondary
Interlock
Switch
Monitor
Switch
Door
Sensing
Switch
and secondary interlock switch contacts fail to open, the
monitor fuse blows simultaneously with closing of the
monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK RELAY (RY1),
SECONDARY INTERLOCK SWITCH AND
MONITOR SWITCH FOR PROPER OPERATION.
(REFER TO CHAPTER “TEST PROCEDURE”).
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
ANTENNA MOTOR
The antenna motor rotates the stirrer antenna located on the
bottom of the oven cavity, so that the food on the ceramic
shelf is cooked evenly during cooking. The antenna motor
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 sur-
rounding the magnetron and cools the magnetron. This air is
channelled through the oven cavity to remove steam and
vapors given off from the heating food. It is then exhausted
through the exhausting air vents at the oven cavity.
MONITOR FUSE
1. The monitor 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 short-
circuited, this monitor fuse blows to prevent an electric
shock or fire hazard.
THERMAL CUT-OUT 145˚C (MAGNETRON)
This thermal cut-out protects the magnetron against over-
heating. If the temperature goes up higher than 293˚F (145˚C)
because the fan motor is interrupted or the ventilation open-
ings are blocked, the thermal cut-out will open and line
voltages to the high voltage transformer will be cut off and the
operation of the magnetron will be stopped. The thermal cut-
out will not resume.
THERMAL CUT-OUT 125˚C (OVEN)
The thermal cut-out located on the top of the oven cavity is
designed to prevent damage to the oven if the food in the
oven catches fire due to over heating produced by improper
setting of the cooking time or failure of control unit. Under
normal operation, the oven thermal cut-out remains closed.
However, when abnormally high temperatures are reached
within the oven cavity, the oven thermal cut-out will open at
257˚F(125˚C) causing the oven to shut down. The thermal
cut-out will not resume.
NOISE FILTER
The noise filter prevents the radio frequency interference that
might flow back in the power circuit.

R-21JCA-F
9
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 monitor fuse, check the monitor switch, primary interlock relay
(RY1), door sensing switch and secondary interlock switch before replacing the monitor fuse. If monitor fuse is
replaced, the monitor switch must also be replaced. Use part FFS-BA015WRK0 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.
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.
TEST PROCEDURE
CONDITION PROBLEM
POSSIBLE CASE
AND
DEFECTIVE PARTS
Home fuse or circuit breaker blows when
power cord is plugged into wall outlet.
Monitor fuse blows when power cord is
plugged into wall outlet.
Oven lamp does not light, and fan motor
and antenna motor do not operate.
Oven does not go into cook cycle when
Light Up Dial turned.
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).
OFF
CONDITION
COOKING
CONDITION
MAGNETRON POWER TRANSFORMER H.V. RECTIFIER ASSEMBLY HIGH VOLTAGE CAPACITOR THERMAL CUT-OUT SECONDARY INTERLOCK SWITCH PRIMARY INTERLOCK SYSTEM MONITOR SWITCH MONITOR FUSE NOISE FILTER CONTROL PANEL RELAY (RY2) FOIL PATTURN ON P.W.B. LOW VOLTAGE WRONG OPERATION DIRTY OVEN CAVITY SHORTED IN POWER CORD OVEN LAMP OR SOCKET COOLING FAN MOTOR ANTENNA MOTOR
SHORT OR OPENED WIRING
ABCDEFFGHI JKL RE RE RE RE RE CK CK CK

R-21JCA-F
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AMAGNETRON ASSEMBLY TEST
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
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. 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.
5. 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.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
MICROWAVE OUTPUT POWER
The following test procedure should be carried out with the microwave oven in a fully assembled condition
(outer case fitted).
HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD BE
OBSERVED.
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 10(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 34.7 to
64.6˚F(19.3 to 35.9˚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 120 volts and the oven cavity is clean.
BPOWER TRANSFORMER TEST
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 primary input terminals and measure the resistance of the transformer with an ohmmeter.
Check for continuity of the coils with an ohmmeter. On the 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 85 ohms;
the resistance of the filament coil should be less than 1 ohm.
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.
(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)

R-21JCA-F
11
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
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. 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.
CHIGH VOLTAGE RECTIFIER TEST
DHIGH VOLTAGE CAPACITOR TEST
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. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and
check for a 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 an open circuit 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.
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.
ETHERMAL CUT-OUT TEST 125˚C (OVEN)
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. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the thermal cut-out reaches approximately 257˚F(125˚C).
An open thermal cut-out indicates overheating of the oven, exchange the thermal cut-out and check inside
of oven cavity and for improper setting of cooking time or operation of control unit. Check for restricted air
flow through the vent holes of the oven cavity, especially the cooling fan and air guide.
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.
THERMAL CUT-OUT TEST 145˚C (MAGNETRON)
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. A continuity check across the thermal cut-out terminals should indicate a closed circuit. If the temperature
of the magnetron reaches approximately 293˚F(145˚C), the thermal cut-out opens. An open thermal cut-
out indicates overheating of the magnetron. Check for restricted air flow to the magnetron, especially the
cooling fan air guide.
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.
CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,
REPLACE THERMAL CUT-OUT.

R-21JCA-F
12
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
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. 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 secondary interlock 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.
PRIMARY 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.
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.
NOTE: If the door sensing switch contacts fail in the open position and the door is closed, the cooling
fan, antenna and oven light will be activated by RY1.
PRIMARY INTERLOCK RELAY (RY1)
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 two (2) wire leads from the male tab terminals of the Primary Interlock Relay. 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.
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.
F SECONDARY INTERLOCK SWITCH TEST
SCREW
DRIVER
MONITOR
SWITCH
OHMMETER
WHT/ WHT
GMONITOR SWITCH TEST
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. Before performing this test, make sure that the secondary interlock switch and the primary interlock relay
are operating properly, according to the above Switch Test Procedure. Disconnect the wire lead from the
monitor switch (COM) 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 screw driver 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
(COM) terminal and check the continuity of
the monitor circuit.
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.

R-21JCA-F
13
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
JCONTROL PANEL ASSEMBLY TEST
WARNING : To prevent an electric shock do not touch the electrical parts and the printed wiring
board. Because the control unit is "TRANSLESS CIRCUIT" and many electrical parts
are used at A.C. line voltage.
The 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 troubleshooting by unit replacement is described
according to the symptoms indicated.
Before testing,
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 these leads remain isolated from other components and oven chassis by using insulation
tape.
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. If the monitor fuse is blown when the door is opened, check the primary interlock relay, secondary interlock
switch and monitor switch according to the "TEST PROCEDURE" for those switches before replacing the
blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE PRIMARY INTERLOCK
RELAY, SECONDARY INTERLOCK SWITCH, DOOR SENSING SWITCH AND MONITOR
SWITCH FOR PROPER OPERATION.
If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch must be
replaced with "monitor fuse and monitor switch assembly" part number FFS-BA015WRK0, even if the
monitor switch operates normally. The monitor fuse and monitor switch assembly is comprised of a 20
ampere fuse and 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.
HBLOWN MONITOR FUSE TEST
FUSE
LINE CROSS CAPACITOR 0.22 F AC250V
WHITE RED
NOISE SUPPRESSION COIL
LINE BYPASS
CAPACITOR
0.003300 F / AC 125V
LINE BYPASS
CAPACITOR
0.003300 F / AC 125V
20A
NOISE FILTER
NL
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 lead wires from the terminal the noise
filter. Using an ohmmeter, check between the terminals
as described in the following table. If incorrect reading are
obtained, replace the noise filter.
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.
MEASURING POINT INDICATION OF OHMMETER
Between N and L Open circuit
Between terminal N and WHITE Short circuit
Between terminal L and RED Short circuit
INOISE FILTER TEST

R-21JCA-F
14
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
6) After that procedure, re-connect the power supply cord.
1. Control Panel
The following symptoms indicate a defective control unit.
1-1 In connection with LEDs
a) At a certain LED, all or some LEDs do not light up.
b) At a certain LED, brightness is low.
c) Only one LED does not light up.
d) All or some LEDs continue to light up.
e) A certain group of LEDs do not light up.
f) The LEDs flicker.
1-2 Other possible troubles caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock is not possible.
c) Cooking time can not be set.
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 all leads removed from components during testing.
5) Re-install the outer case (cabinet).
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions.
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 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 No. 5 of the 3 pin connector (A) and the common
terminal of the relay RY1 on the control unit with an A.C. voltmeter.
The meter should indicate 120 volts, if not check oven circuit.
RY1 AND RY2 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave 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. 19.2V D.C. Oven lamp / Antenna motor / Cooling fan motor
RY2 Approx. 19.9V D.C. Power transformer
The voltage under the condition when all LEDs light up.
8. Disconnect the power supply cord and then remove outer case.
9. Open the door and block it open.
10.Discharge high voltage capacitor.
11.Reconnect all leads removed from components during testing.
12.Re-install the outer case (cabinet).
13.Reconnect the power supply cord after the outer case is installed.
14.Run the oven and check all functions.
KRELAY TEST

R-21JCA-F
15
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the PWB,
this foil pattern acts as a fuse.
1. Foil pattern check and repairs.
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) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
1Only pattern at "a" is broken. *Insert jumper wire J1 and solder.
2 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
5) Make a visual inspection of the varistor.
Check for burned damage.
6) Reconnect all leads removed from components during testing.
7) Re-install the outer case (cabinet).
8) Reconnect the power supply cord after the outer case is installed.
9) Run the oven and check all function.
2. Follow the troubleshooting guide given below, if indicator does not light up after above check and repairs
are finished.
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 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) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
The rated AC voltage is not present between
1 Pin No. 5 of the 3-pin connector (A) and the Check supply voltage and oven power cord.
common terminal of the relay RY1.
8) Disconnect the power supply cord and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
L FOIL PATTERN ON THE PRINTED WIRING BOARD TEST
RY2
RY1
J1
CNA
VRS1
5
b
d
c
a

R-21JCA-F
16
DESCRIPTION OF LSI
LSI
The I/O signal of the LSI is detailed in the following table.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
Control Unit
Control unit consists of LSI, power source circuit, synchroniz-
ing signal circuit, reset circuit, buzzer circuit, encoder circuit
and indicator circuit.
1) LSI
This LSI controls the encoder signal, relay driving signal for
oven function, buzzer signal and LED signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control unit.
Symbol Voltage Application
VC +5V (*) LSI(I-1)
VR +20V (*) RELAY(RY1, RY2)
(*) The voltage under the condition when all LEDs light up.
The voltage VR will vary according to the quantity of the
LEDs which light up.
3) Synchronizing Signal Circuit
The power source synchronizing signal is available in order
to compose a basic standard time in the clock circuit. It
accompanies a very small error because it works on
commercial frequency.
4) Reset Circuit
A circuit to generate a signals which resets the LSI to the
initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (completion sound).
6) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, antenna motor and light
the oven lamp.
8) Encoder
The encoder generates the pulse signal, and the pulse
signal is sent to the LSI.
9) Indicator Circuit
Indicator elements are the Light-emitting diodes (LD1-
LD20).
This circuit consists of 4-digits and 5 segments.
Pin No. Signal I/O Description
1D3OUT Segment data signal.
Signal is input to the cathodes of the light-emitting diodes (LD1, LD6, LD11 and LD16).
2D4OUT Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD16 - LD20).
3D5OUT Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD11 - LD15).
4D6OUT Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD6 - LD10).
5D7OUT Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD1 - LD5).
6P20 IN Connected to VDD terminal.
7P21 IN Connected to VSS terminal.
8P22 IN Signal coming from encoder.
When the encoder is turned, the contacts of encoder make pulse signals. And pulse
signals are input into P22.

R-21JCA-F
17
9RESET IN Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied. Temporarily
set to "L" level the moment power is applied, at this time the LSI is reset. Thereafter
set at "H" level.
10 CNVSS IN Power source voltage.
The power source voltage to drive the LSI is input to CNVSS terminal.
11 XOUT OUT Internal clock oscillation frequency control output.
Output to control oscillation input of XIN.
12 XIN IN Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to XOUT terminal.
13 VSS IN Power source voltage: 0V.
The power source voltage to drive the LSI is input to VSS terminal. Connected to VC.
14 VDD IN Power source voltage: +5V.
The power source voltage to drive the LSI is input to VDD terminal.
15 N.F IN Connected to VSS terminal.
16 INT0 IN Signal coming from encoder.
Signal similar to P22. Pulse signals are input into INT0.
17 INT1 IN Signal to synchronize LSI with commercial power source frequency.
This is basic timing for all real time processing
of LSI.
18 AIN0 IN Input signal which communicates the door open/close information to LSI.
Door closed; "L" level signal.
Door opened; "H" level signal.
19-21 AIN1-AIN3 IN Terminal to change functions according to the model.
Signal in accordance with the model in operation is applied to set up its function.
22 P00 OUT Terminal not used.
23 P01 OUT Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay (RY2). In 100% power operation, the signals hold
"H" level during microwave cooking and "L" level while not cooking.
24 P02 OUT Oven lamp, turntable motor and fan motor driving signal(Square Waveform :
60Hz).
To turn on and off shut-off relay (RY1). The square
waveform voltage is delivered to the relay (RY1)
driving circuit and relay(RY2) control circuit.
25 P03 OUT Signal to sound buzzer.
Completion sound.
26 P10 OUT Terminal not used.
27-29 P11-P13 OUT Segment data signal.
Signal is input to the cathodes of the light-emitting diodes (LD5, LD10, LD15 and LD20).
30 D0 OUT Segment data signal.
Signal is input to the cathodes of the light-emitting diodes (LD4, LD9, LD14 and LD19).
31 D1 OUT Segment data signal.
Signal is input to the cathodes of the light-emitting diodes (LD3, LD8, LD13 and LD18).
32 D2 OUT Segment data signal.
Signal is input to the cathodes of the light-emitting diodes (LD2, LD7, LD12 and LD17).
Pin No. Signal I/O Description
16.7 msec
H : +5V
L: 0V
16.7 msec
During cooking
H
L
H: +5V
L: 0V
2.0 sec

R-21JCA-F
18
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the circuits.
When handling these parts, the following precautions should
be strictly followed. CMOS LSI have extremely high
impedance at its input and output terminals. For this reason,
it is easily influenced by the surrounding high voltage power
source, static electricity charge in clothes, etc., and
sometimes it is not fully protected by the built-in protection
circuit.
In order to protect CMOS LSI.
1) When storing and transporting, thoroughly wrap them in
aluminium foil. Also wrap PW boards containing them in
aluminium foil.
2) When soldering, ground the technician as shown in the
figure and use grounded soldering iron and work table.
2. Servicing of Touch Control Panel
We describe the procedures to permit servicing of the touch
control panel of the microwave oven and the precautions
you must take when doing so. To perform the servicing,
power to the touch control panel is available either from the
power line of the oven itself or from an external power
source.
(1) Servicing the touch control panel with power supply of
the oven :
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE MICRO-
WAVE OVEN IS STILL LIVE DURING SERVICING AND
PRESENTS A HAZARD .
Therefore, before checking the performance of the touch
control panel,
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 these leads remain isolated from other
components and oven chassis by using insulation
tape.
6) After that procedure, re-connect the power supply
cord.
After checking the performance of the touch control
panel,
1) Disconnect the power supply cord.
2) Open the door and block it open.
3) Re-connect the leads to the primary of the power
transformer.
4) Re-install the outer case (cabinet).
5) Re-connect the power supply cord after the outer
case is installed.
6) Run the oven and check all functions.
A. On some models, the power supply cord between the touch
control panel and the oven itself is so short that the two can't
be separated. For those models, check and repair all the
controls (sensor-related ones included) of the touch control
approx. 1M ohm
TOUCH CONTROL PANEL SERVICING
panel while keeping it connected to the oven.
B. On some models, the power supply cord between the touch
control panel and the oven proper is so long enough that
they may be separated from each other. For those models,
therefore, it is possible to check and repair the controls of
the touch control panel while keeping it apart from the oven
proper; in this case you must short both ends of the door
sensing switch (on PWB) of the touch control panel with a
jumper, which brings about an operational state that is
equivalent to the oven door being closed. As for the sensor-
related controls of the touch control panel, checking them is
possible if the dummy resistor(s) with resistance equal to
that of the controls are used.
(2) Servicing the touch control panel with power supply
from an external power source:
Disconnect the touch control panel completely from the
oven proper, and short both ends of the door sensing switch
(on PWB) of the touch control panel, which brings about an
operational state that is equivalent to the oven door being
closed. Connect an external power source to the power
input terminal of the touch control panel, then it is possible
to check and repair the controls of the touch control panel;
it is also possible to check the sensor-related controls of the
touch control panel by using the dummy resistor(s).
3. Servicing Tools
Tools required to service the touch control panel assembly.
1) Soldering iron: 60W
(It is recommended to use a soldering iron with a
grounding terminal.)
2) Oscilloscope: Single beam, frequency range: DC -
10MHz type or more advanced model.
3) Others: Hand tools
4. Other Precautions
1) Before turning on the power source of the control unit,
remove the aluminium foil applied for preventing static
electricity.
2) Connect the connector of the key unit to the control unit
being sure that the lead wires are not twisted.
3) After aluminium foil is removed, be careful that abnormal
voltage due to static electricity etc. is not applied to the
input or output terminals.
4) Attach connectors, electrolytic capacitors, etc. to PWB,
making sure that all connections are tight.
5) Be sure to use specified components where high
precision is required.