Viking Range DMOR200SS User Manual

MODEL

DMOR200SS

DMOR200SS

SERVICE MANUAL

for Microwave Oven

S39M307DMOR20

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 .................................................................................................................3

MICROWAVE MEASUREMENT PROCEDURE .....................................................................................................4

FOREWORD AND WARNING ...............................................................................................................................5

PRODUCT SPECIFICATIONS ...............................................................................................................................6

GENERAL INFORMATION....................................................................................................................................6

OPERATION ...........................................................................................................................................................9

TROUBLESHOOTING GUIDE .............................................................................................................................13

TEST PROCEDURE ............................................................................................................................................15

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE.................................................................27

PICTORIAL DIAGRAM .........................................................................................................................................35

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

1

DMOR200SS

NOTICE

In the interest of user-safety the oven should be restored to its original condition and only parts identical
those specified should be used.

WARNING TO SERVICE PERSONNEL: Microwave ovens contain circuitry capable of producing very high
voltage and current. Contact with the following parts may result in a severe, possibly fatal, electrical shock.
(High Voltage Capacitor, High Voltage Power Transformer, Magnetron, High Voltage Rectifier Assembly, High

Voltage Harness etc..)

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 Viking Service immediately @ 1­888-845-4641.

If the unit operates with the door open, service person should (1) tell the user not to operate the oven and
(2) contact VIKING, plus the Department Of Health, Canada and/or the Food and Drug Administration's
Center for Devices and Radiological Health immediately.

Service personnel should inform VIKING 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.

2

WARNING TO SERVICE PERSONNEL

Don't Touch !
Danger High Voltage

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

Transformer, Magnetron, High Voltage Rectifier
Assembly, High Voltage Harness etc..

Read the Service Manual carefully and follow all
instructions.

may result in a severe, possibly

DMOR200SS

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
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.

Ensure that these leads remain isolated from other

5.
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
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.

and re-examine

3

DMOR200SS

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 switch shall prevent microwave radiation emission in excess of the requirement as above
mentioned. Secondary interlock relay and door sensing 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:
USA Survey instruments that comply with the requirement for instrumentation as prescribed by the Federal Performance
Standard for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.

Canadian Survey instruments that comply with the requirement for instrumentation as prescribed by CSA and NHW
performance standard for microwave ovens must be used for testing recommended instruments are , NARDA 8100 and
NARDA 8200.

2) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5

O

C (68OF) 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 non conductive 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.

3) Set the cooking control on Full Power Cooking Mode.

4) Close the drawer 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-drawer leakage test (microwave measurement):

1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the drawer 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 drawer 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 drawer, pull the drawer 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 primary interlock switch/secondary interlock relay does turn the oven OFF before any door movement.

NOTE: After servicing, record data on service invoice and microwave leakage report.

4

SERVICE MANUAL

MICROWAVE OVEN

DMOR200SS

PRODUCT DESCRIPTION

DMOR200SS

FOREWORD

This Manual has been prepared to provide VIKING Products. Service
Personnel with Operation and Service Information for the VIKING MI­CROWAVE OVENS.

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

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.

VIKING RANGE CORPORATION

PREFERRED SERVICE

111 Front Street

Greenwood, Mississippi (MS) 38930 USA

5

DMOR200SS

PRODUCT SPECIFICATION

ITEM DESCRIPTION

Power Requirements 120 Volts / 13 Amperes
60 Hertz
Single phase, 3 wire grounded

Power Output 950 watts (IEC TEST PROCEDURE)
Operating frequency of 2450MHz

Case Dimensions Width 29-15/16"
Height 16- 1/4"
Depth 15- 9/16"

Cooking Cavity Dimensions Width 17-1/2"
Height 9-7/8"

1.5 Cubic Feet Depth 14-15/16"
Hood lamp 2 bulbs, 20W x 2, Incandescent light bulbs
Hood fan Approx. 300 C.F.M.
Control Complement Touch Control System

Clock ( 1:00 - 12:59 )
Timer (0 - 99 min. 99 seconds)

Microwave Power for Variable Cooking
Repetition Rate;

P-HI ..................................................Full power throughout the cooking time

P-90 .....................................................................approx. 90% of Full Power

P-80 .....................................................................approx. 80% of Full Power

P-70 .....................................................................approx. 70% of Full Power

P-60 .....................................................................approx. 60% of Full Power

P-50 .....................................................................approx. 50% of Full Power

P-40 .....................................................................approx. 40% of Full Power

P-30 ....................................................................approx. 30% of Full Power

P-20 .....................................................................approx. 20% of Full Power

P-10 .....................................................................approx. 10% of Full Power

P-0 ..................................................... No power throughout the cooking time

KEEP WARM PLUS pad, POPCORN pad, HOT WATER pad

REHEAT pad, DEFROST pads, Number selection pads, REHEAT pads,
POWER LEVEL pad, TIMER / CLOCK pad, FRESH VEGETABLES pad,
LIGHT HI / LO button, FAN HI / LO button, SENSOR COOK pads,
STOP/CLEAR button, START/ ADD-A-MINUTE button, HELP pad.

Oven Cavity Light 20W x 1 Incandescent light bulb
Safety Standard CUL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Sub chapter J and Canadian Standards

Association. Health CANADA.
Weight Approx. 55 lbs.

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.

6

DMOR200SS

3-Pronged Plug

Grounded
Receptacle Box

Grounding Pin

3-Pronged Receptacle

Product Controls

Oven door with see-through1
window

Door hinges2

Waveguide cover3

DO NOT REMOVE.

Turntable motor shaft4

Oven light - on during operation 5
and when the door is open.

Safety door latches - door must 6
be securely closed for the oven
to operate.

Cook and time display7

LIGHT Hi/Lo pad - controls8
interior light

Press the LIGHT Hi/Lo pad once
for Hi. Press again for Lo. Press a
third time to turn the light o.

FAN Hi/Lo pad - controls fan9

Press the FAN Hi/Lo pad once
for Hi. Press again for Lo. Press a
third time to turn the fan o.

Control panel 10

One touch DOOR OPEN 11
Push to open door

Louver12

Nameplate13

Louver screws - remove14
screws to replace
charcoal lter.

Removable turntable15

- rotates clockwise or
counterclockwise
Only remove for cleaning

Removable turntable16
support

1. Carefully place the
turntable support in
the motor shaft in the
center of the oven
oor.

2. Place the turntable on
the turntable support
securely.

Heat deector17

16

2

34 5

7
8

9

10

12

15

16

6

11

13 17

1414

(Front of Microwave)

(Rear of Microwave)

18

19

Light cover18

Grease lters19

Bottom of Unit

Electrical Requirements
The oven is equipped with a 3-prong grounding plug. DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE
GROUNDING PIN FROM THE PLUG.
The power supply cord and plug must be connected to a separate 120 Volt AC, 60 Hz, 15 Amp. or more dedicated line,
using a grounded receptacle. The receptacle should be located inside the cabinet directly above the Microwave Oven/Hood
system mounting location.

OVEN DIAGRAM

7

DMOR200SS

NOTE: Some one-touch cooking features such as "ADD-A-MINUTE" are disabled after three minutes when the oven is

not used. These features are automatically enabled when the door is opened and closed or STOP/CLEAR button
is pressed.

8

OPERATION

DESCRIPTION OF OPERATING SEQUENCE

DMOR200SS

The following is a description of component functions during
oven operation.

OFF CONDITION

Closing the door activates the door sensing switch and primary
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).

1. The display will show flashing "Welcome Press Clear and
Press Clock".

To set any program or set the clock, you must first touch

the STOP/CLEAR button. The display will clear, and " : "
will appear .

COOKING CONDITION

Program desired cooking time touching the NUMBER pads.
When the START button is touched, the following operations
occur:

1. The contacts of relays are closed and components
connected to the relays are turned on as follows.

(For details, refer to Figure O-2)

RELAY CONNECTED COMPONENTS
RY1 Oven lamp / Fan motor / Turntable motor
RY2 Power transformer
RY3, RY4 Hood fan motor
RY5, RY6 Hood lamp

2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3.3 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 wave guide 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,third door switch and primary interlock relay are
activated with the following results. The circuits to the
stirrer motor, the cooling fan motor, the turntable
motor, and the high voltage components are de-
energized, and the digital read-out displays the time
still remaining in the cook cycle when the door was
opened.

7. The monitor switch is electrically monitoring the operation

of the secondary interlock switch, third door switch and
door sensing switch is mechanically associated with the
door so that it will function in the following sequence.

(1) When the door opens from a closed position, the

primary interlock relay, door sensing switch, third
door switch and secondary interlock switch open
their contacts, and then the monitor switch
contacts close.

(2) When the door is closed from the open position, the

monitor switch contacts first open, and then the
contacts of the secondary interlock switch, third
door switch close.
If the secondary interlock switch and third door switch fail
with their contacts closed when the door is opened, the
closing of the monitor switch contacts will form a short
circuit through the monitor fuse, secondary interlock switch
and third door switch, causing the monitor 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 (RY2) which is operated by the control
unit within an interval second time base. Microwave power
operation is as follows:

VARI-MODE ON TIME OFF TIME

Power 10(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. 3
seconds are needed for heating of the magnetron
filament.

9

DMOR200SS

To Duct

To Duct

Grease
Filter

Hood
Intake
Duct R

Hood Fan
Motor

Grease
Filter

To Duct

Hood
Intake
Duct R

Hood Fan
Motor

Hood
Intake
Duct R

Hood Exhaust
Louver

Hood Fan
Motor

Charcoal
Filter

VENTILATION METHODS HOT AIR EXHAUST

1. VERTICAL VENTING
For this venting method, hot air rising from the conventional range below is drawn in by the hood fan motor through the

grease filters at the right and left sides of the base cover, up through the right and left sides of the oven cavity, then
discharged vertically at rear center top of the oven, into the customer's vent system.

2.

HORIZONTAL VENTING

The air handing is the same as VERTICAL VENTING except that the final air discharge is directed horizontally out from

the top rear of the oven into the customer's vent system.

3. RE-CIRCULATION (INSIDE VENTING)
The air handing is the same as VERTICAL VENTING except that the final air discharge is directed horizontally through

the upper front of the oven into the kitchen. IN this case, the accessory charcoal filter RK-240 must be provided to filter
the air before it leaves the oven.

10

NOTE: " " indicates components with potential above 250V.

CAVITYTHERMAL
CUTOUT

120VAC
60Hz

BLK

WHT

BLK

WHT

GRN

MAGNETRON

TEMP

FUSE

PRIMARY
INTERLOCK
SWITCH

POWER
TRANSFORMER

MAGNETRON

HIGH

VOLTAGE

CAPACITOR

GRY

GND

GRY

COM.

N.O.

N.C.

HIGH

VOLTAGE

RECTIFIER

NOISE
FILTER

RED

RED

H

N

C1

C2

C3

L

GND

BLK

MONITOR
FUSE

COM.

WHT

GRY

BRN

BRN

WHT

B2

B1

CONTROL UNIT

N.O.

(RY2)

COM.

DOOR
SENSING
SWITCH

TTM

FM

TURN
TABLE
MOTOR

FAN
MOTOR

OVEN
LAMP

ORG

SECONDARY
INTERLOCK
RELAY

RED

F3

F2

F1

SENSOR

(RY1)

OVEN
LAMP
RELAY

HUMIDITY

BRN

THIRD
DOOR
SWITCH

N.O.

COM.

COM.

MONITOR

SWITCH

OL

GRY

HOOD

HOOD
MOTOR

BLU

N.O.

HL

BLK

RED

ORG

BLK

BLK

GRY

B5

A5

RY4

RY6

RY5

RY3

NC

LOW

BLK

WHT

HIGH

B7

B9

CAPACITOR

A1

A3

B1

B3

RED

YLW

GRY

WHT

GRY

BLU

BLU
BRN

RED

WHT

BRN

WHT

HL

BLU or

PNK

CUTOUT

THERMAL

HOOD FAN

RED or

WHT

WHT

WHT

GRY

GRY

CAVITYTHERMAL
CUTOUT

120VAC
60Hz

BLK

WHT

BLK

WHT

GRN

MAGNETRON

TEMP

FUSE

PRIMARY
INTERLOCK
SWITCH

POWER
TRANSFORMER

MAGNETRON

HIGH

VOLTAGE

CAPACITOR

GRY

GND

GRY

COM.

N.O.

N.C.

HIGH

VOLTAGE

RECTIFIER

NOISE
FILTER

RED

RED

H

N

C1

C2

C3

L

GND

BLK

MONITOR
FUSE

COM.

WHT

GRY

BRN

BRN

WHT

B2

B1

CONTROL UNIT

N.O.

(RY2)

COM.

DOOR
SENSING
SWITCH

TTM

FM

TURN
TABLE
MOTOR

FAN
MOTOR

OVEN
LAMP

ORG

SECONDARY
INTERLOCK
RELAY

RED

F3

F2

F1

SENSOR

(RY1)

OVEN
LAMP
RELAY

HUMIDITY

BRN

THIRD
DOOR
SWITCH

N.O.

COM.

COM.

MONITOR

SWITCH

OL

GRY

HOOD

HOOD
MOTOR

BLU

N.O.

HL

BLK

RED

ORG

BLK

BLK

GRY

B5

A5

RY4

RY6

RY5

RY3

NC

LOW

BLK

WHT

HIGH

B7

B9

CAPACITOR

A1

A3

B1

B3

RED

YLW

GRY

WHT

GRY

BLU

BLU
BRN

RED

WHT

BRN

WHT

HL

BLU or

PNK

CUTOUT

THERMAL

HOOD FAN

RED or

WHT

WHT

WHT

GRY

GRY

DMOR200SS

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. CLOCK APPEARS ON DISPLAY.

Figure O-2. Oven Schematic-Cooking Condition

Figure O-1. Oven Schematic-Off Condition

11

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. COOKING TIME PROGRAMMED.

3. VARIABLE COOKING CONTROL
"HIGH".

DMOR200SS

DESCRIPTION AND FUNCTION OF COMPONENTS

DOOR OPEN MECHANISM

The door is opened by pulling the door handle, refer to the
Figure D-1.

simultaneously with closing of the monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN MONITOR

FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK RELAY (RY2), SEC­ONDARY INTERLOCK SWITCH, THIRD DOOR
SWITCH AND MONITOR SWITCH FOR
PROPER OPERATION. (REFER TO CHAP­TER "TEST PROCEDURE").

NOTE: MONITOR FUSE, MONITOR SWITCH AND

SECONDARY INTERLOCK SWITCH ARE
REPLACED AS AN ASSEMBLY

TEMPERATURE FUSE (MG)

The temperature fuse located near the waveguide 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 temperature fuse remains
closed. However, the temperature fuse will open at 302

O

F

(150

O

C) causing the oven to shut down.

THERMAL CUT-OUT (HOOD )

This thermal cut-out located on the right base plate. It is
designed to automatically turn on the hood fan motor
whenever the hot air rising from the conventional range
below causes the temperature at the thermal cut-out to rise
to 140

O

F (60OC) or higher, thus removing this hot air from
around microwave oven. When the temperature around the
thermal cut-out drops to 113

O

F (45OC) or lower, the thermal

cut-out shuts off the hood fan motor.

THERMAL CUT-OUT (CAVITY )

This thermal cut-out is located on the top of the oven cavity.
It is designed to prevent damage to the oven unit if the food
in the oven catches fire due to overheating produced by
improper setting of cooking time or failure of control unit.
Under normal operation, the thermal cut-out remains
closed. However, the thermal cut-out will open at 293

O

F

(145

O

C) causing the oven to shut down.

TURNTABLE MOTOR

The turntable motor rotates the turntable located on the
bottom of the oven cavity, so that the foods on the turntable
cook evenly during cooking. Turntable will turn in either
direction. The turntable motor can be turned off by touching
TURNTABLE ON/OFF pad.

COOLING FAN MOTOR

The cooling fan motor drives a blade which draws external
cool air. This cool air is directed through the air vanes
surrounding the magnetron and cools the magnetron. This
air is channelled through the oven cavity to remove steam
and vapors given off from the heating foods. It is then
exhausted through the exhausting air vents at the oven
cavity.

HOODFAN MOTOR

The hood fan motor is a two-speed, single-phase, double

Figure D-1. Door Open Mechanism

DOOR SENSING SWITCH, SECONDARY INTER­LOCK SWITCHE AND THIRD DOOR SWITCH

The secondary interlock switch is mounted in the lower
position of the latch hook, the door sensing switch in the
primary interlock system is mounted in the upper position
of the latch hook and the third door switch is mounted on
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 circuit to all 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
blowing the monitor fuse when the contacts of the primary
interlock relay (RY2) and secondary interlock switch and
third door switch fail to open when the door is opened.

Functions:

1. When the door is opened, the monitor switch contact
close (to the ON condition) due to their being normally
closed. At this time the primary interlock relay (RY2),
secondary interlock switch and third door switch are in
the OFF condition (contacts open) due to their being
normally open contact switches. And the contacts of
relay (RY1) are in the ON condition (contacts close).

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 and third door
switch contacts close. (On opening the door, each of
these switches operate inversely.)

3. If the door is opened, and the primary interlock relay
(RY2) and secondary interlock switch and third door
contacts fail to open, the monitor fuse blows

Door Sensing
Switch

Monitor Switch

Switch Lever

Secondary

Switch

Latch Heads

Door

Third door

Switch

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