SHARP R21HC Service Manual

SERVICE MANUAL

S7813R21HCP//

LIGHT DUTY

COMMERCIAL

MICROWAVE OVEN

R-21HC

1000W/ R-21HC

TIME GUIDE FOR ONE SERVING

15 - 30 sec.

30 - 60 sec.

Bagel, Roll

Hot Dog

Muffin, Pastry

Pizza Slice

Pie Slice

Small Sandwich

1 - 2 min.

2 - 3 min.

Beverage, Soup

Casserole, Stew

Large Sandwich

Chili, Chowder

Popcorn, 1.5 oz.

Popcorn, 3.5 oz.

50

1

40

F

E

1.5

30

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20

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2

10

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0

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2.5

M

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A

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M

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6

5

INSTRUCTIONS

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".

N

O

3

P

4

MODEL

R-21HC

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

CONTROL PANEL...............................................................................................................................................16

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................19

PICTORIAL DIAGRAM ........................................................................................................................................26

CONTROL PANEL CIRCUIT .............................................................................................................................. 27

PRINTED WIRING BOARD .................................................................................................................................28

PARTS LIST ........................................................................................................................................................29

PACKING AND ACCESSORIES .........................................................................................................................31

SHARP CORPORATION

This document has been published to be used for after
sales service only.
The contents are subject to change without notice.

R-21HC

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.

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-21HC

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 microwave leakage test should be carried out.

1

R-21HC

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

R-21HC

LIGHT DUTY

COMMERCIAL

MICROWAVE OVEN

R-21HC

FOREWORD

This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP MICROWAVE OVEN, R-21HC.

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.

PRODUCT DESCRIPTION

GENERAL INFORMATION

OPERATION

TROUBLESHOOTING GUIDE AND
TEST PROCEDURE

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-21HC

SPECIFICATION

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

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 RE-

MOVE THE ROUND GROUNDING PRONG FROM THIS PLUG.

3-Pronged Plug

Grounding Pin

3-Pronged Receptacle

Grounded
Receptacle Box

4

R-21HC

OVEN DIAGRAM

1

912

3 2

14

13

11

4

10

8

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

15

76

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

TOUCH CONTROL PANEL

TIME GUIDE FOR ONE SERVING

5

16

15 - 30 sec.
Bagel, Roll
Muffin, Pastry
Pie Slice

1 - 2 min.
Beverage, Soup
Large Sandwich
Popcorn, 1.5 oz.

40

30

C

20

B

10

A

0

6

INSTRUCTIONS

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".

50

D

T

1

F

E

S

R

5

30 - 60 sec.
Hot Dog
Pizza Slice
Small Sandwich

2 - 3 min.
Casserole, Stew
Chili, Chowder
Popcorn, 3.5 oz.

1.5

G

H

I

2

J

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M

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O

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P

Q

4

2.5

Light Up Dial for setting cooking time.

5

R-21HC

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
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 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, 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 Light Up
Dial indicates time still remaining in the cook cycle 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.

6

R-21HC

SCHEMATIC

NOTE: CONDITION OF OVEN

1. LIGHT UP DIAL OFF.

2. DOOR CLOSED.

MONITOR
FUSE 20A

AC120V
60 Hz

THERMAL
CUT-OUT
125˚C (OVEN)

A5

A3 A1

NOTE: Indicates components with potential above 250 V.

THERMAL
CUT-OUT
145˚C (MAG.)

CONTROL UNIT

DOOR SENSING
SWITCH

SECONDARY
INTERLOCK SWITCH

RY1

PRIMARY

RY2

INTERLOCK

RELAY

COOK

RELAY

OL FM AM

OVEN 
LAMP

FAN 
MOTOR

ANTENNA 
MOTOR

POWER
TRANSFORMER

MONITOR SWITCH

CAPACITOR

0.94 µF
2400V

MAGNETRON

RECTIFIER

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. LIGHT UP DIAL ON.

MONITOR
FUSE 20A

AC120V
60 Hz

THERMAL
CUT-OUT
125˚C (OVEN)

A5

A3 A1

Figure O-1 Oven Schematic-OFF Condition

THERMAL
CUT-OUT
145˚C (MAG.)

CONTROL UNIT

DOOR SENSING
SWITCH

RY1

PRIMARY

OVEN 
LAMP

RY2

INTERLOCK

RELAY

COOK

RELAY

OL FM AM

FAN 
MOTOR

ANTENNA 
MOTOR

POWER
TRANSFORMER

MONITOR SWITCH

CAPACITOR

0.94 µF
2400V

MAGNETRON

RECTIFIER

SECONDARY
INTERLOCK SWITCH

Figure O-2 Oven Schematic-Microwave cooking Condition

7

R-21HC

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.

Latch Switch
Lever C

Latch Head

Latch Hook

Latch Switch
Lever A

Secondary
Interlock
Switch

Latch Switch
Lever B

Monitor
Switch

Door
Sensing
Switch

Handle
Lever

Door
Handle

Latch
Lever

Latch Head

Figure D-1. Door Open Mechanism

DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES

The secondary interlock switch is mounted in the upper
position 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) 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
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 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 (RY1) 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 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 over­heating. If the temperature goes up higher than 293˚F
(145˚C) because the fan motor is interrupted or the ventila­tion openings 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.

8

R-21HC

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.
CK = Check / RE = Replace

TEST PROCEDURE

ABCDEFFGHI JK

RE RE RE RE RE

CK CK CK

POSSIBLE CASE

AND 

DEFECTIVE PARTS

CONDITION PROBLEM

Home fuse or circuit breaker blows when

OFF
CONDITION

COOKING
CONDITION

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).

MAGNETRON

POWER TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE CAPACITOR

THERMAL CUT-OUT

SECONDARY INTERLOCK SWITCH

PRIMARY INTERLOCK SYSTEM

MONITOR SWITCH

MONITOR FUSE

CONTROL PANEL

RELAY (RY2)

FOIL PATTURN ON P.W.B.

OVEN LAMP OR SOCKET

COOLING FAN MOTOR

ANTENNA MOTOR

LOW VOLTAGE

WRONG OPERATION

SHORTED IN POWER CORD

SHORT OR OPENED WIRING

DIRTY OVEN CAVITY

9