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1. Control panel
2. Door opening button
3. Waveguide cover
4. Seal packing
5. Oven cavity
6. Door
7. Door safety latch

8. Door hinges
9. Door seals and sealing surfaces
10.Oven lamp
11.Ventilation openings
12.Outer case
13.Power cord

1. Place the roller stay on the floor of the oven cavity,

engaging shaft into turntable motor shaft.

2. Then place the turntable on the roller stay.

12

11

13

5

10

9

8

7

6

4

3

7

1

2

Turntable

Roller stay

Seal packing

COOKING CONTROL

TIMER (0 - 30 minutes)

COOING & DEFROST GUIDE

4

1. When the timer knob is at "0", the oven is OFF condi-

tion.

2. Closing the oven door activates the monitored latch

switch and the latch switch.

IMPORTANT
When the oven door is closed, the contacts (COM-NC) of
the monitor switch  must be open.
When the microwave oven is plugged in a wall outlet, rated
voltage is supplied to the noise filter and the control unit.

HIGH COOKING
Set the cooking control to HIGH and then set the timer.

1. Following components are energized.

High voltage rectifier

High voltage transformer

High voltage capacitor

High voltage fuse

Turntable motor

Timer motor

Fan motor

Magnetron

Oven lamp

Control unit

CONNECTED COMPONENTS

RELAY

High voltage transformer

RY1

2. Rated voltage is supplied to the primary winding of the

high voltage transformer . The voltage is converted to
about 3.3 volts A.C. output on the filament winding and
high voltage of approximately 2000 volts A.C. on the
secondary winding.

3. The filament winding voltage (3.3 volts) heats the

magnetron filament and the high voltage (2000 volts) is
sent to the voltage doubling circuit, where it is doubled
to negative voltage of approximately 4000 volts D.C..

4. The 2450 MHz microwave energy produced in the

magnetron  generates a wave length of 12.24 cm. This
energy is channelled through the waveguide (transport
channel) into the oven cavity, where the food is placed
to be cooked.

5. When the cooking time is up, the timer returns to "0",

the bell rings and the contacts of the timer switch are
opened. The following components are turned off.

High voltage rectifier

High voltage transformer

High voltage capacitor

High voltage fuse

Turntable motor

Timer motor

Fan motor

Magnetron

Oven lamp

Control unit

6. When the oven door is opened during a cook cycle, the

switches come to the following position and they are
common to the other cooking conditions too.

          CONDITION
DURING

DOOR OPEN

SWITCH

CONTACT

COOKING

(NO COOKING)

Monitored latch switch COM-NO

Closed

  Open

Latch switch

COM-NO

Closed

  Open

Monitor switch

COM-NC

Open

  Closed

The circuits to the high voltage transformer , turntable
motor , timer motor , fan motor , oven lamp  and control

unit are cut off when the contacts (COM-NO) of the
monitored latch switch  and latch switch  are made
open.
The timer stops to indicate how much cooking time
remains.

7. MONITOR SWITCH CIRCUIT

The monitor switch  is mechanically controlled by oven
door, and monitors the operation of the monitored latch
switch .

7-1 When the oven door is opened during or after the

cycle of a cooking program, the monitored latch
switch  and latch switch  must open their contacts
(COM-NO) first. After that the contacts (COM-NC) of
the monitor switch  can be closed.

7-2. When the oven door is closed, the contacts (COM-

NC) of the monitor switch  must be opened first. And
then the contacts (COM-NO) of the monitored latch
switch  and the latch switch  are closed.

7-3. When the oven door is opened and the contacts

(COM-NO) of the monitored latch switch  and con-
tacts of the timer switch remain closed. The fuse
T6.3A will blow, because the monitor switch is closed
and a short circuit is caused.

When the microwave oven is preset for variable cooking
power, rated voltage is supplied to the high voltage trans-
former intermittently within a 32-second time base through
the relay contact which is coupled with the current-limiting
relay. The following levels of microwave power are given.

SETTING;

NOTE: The ON/OFF time ratio does not exactly corre-

spond to the percentage of microwave power,
because approx. 3 seconds are needed for heat-
ing up the magnetron filament.

1. If the oven is set for more than 20 minutes at HIGH,

after the first 20 minutes the power level will automati-
cally adjust itself to 70% power to avoid overcooking.

2. If the oven is operated for more than 90 minutes

continuously (at any power levels), the relay RY1
opens. And the circuit to the high voltage transformer
will be cut off.

32 sec. ON

Approx. 70%

100%

HIGH

MED HIGH

MED

MED LOW

LOW

24 sec. ON

8 sec. OFF

14 sec. OFF

10 sec. OFF

26 sec. OFF

Approx. 50%

18 sec. ON

Approx. 30%

12 sec. ON

Approx. 10%

6 sec. ON

5

The door is opened by pushing the open button on the
control panel, refer to the Figure D-1.
When the open button is pushed, the open button pushes
up the switch lever, and then the switch lever pushes up
the latch head. The latch heads are moved upward and
released from latch hook. Now the door will open.

1. When the oven door is closed, the contacts (COM-NO)

must be closed.

1. When the oven door is closed, the contacts (COM-NC)

must be opened.

2. When the oven door is opened, the contacts (COM-

NC) must be closed.

3. If the oven door is opened and he contacts (COM-NO)

of the moniored latch switch  fail to open, the fuse
T6.3A blows immediately after closing the contacts
(COM-NC) of the monitor switch .

CAUTION: BEFORE REPLACING A BLOWN FUSE

TEST MONITORED LATCH SWITCH  AND
MONITOR SWITCH  FOR PROPER OPERA-
TION.  (REFER TO CHAPTER “TEST PRO-
CEDURE”).

1. The fuse  T6.3A blows when the contacts (COM-NO)

of the monitored latch switch  remain closed with the
oven door open and when the contacts (COM-NC) of
the monitor switch  are closes.

2. If the wire harness or electrical components are short-

circuited, the fuse  T6.3A blows to prevent an electric
shock or fire hazard.

The high voltage fuse blows when the high voltage rectifier
or the magnetron is shorted.

The temperature fuse, located on the top of the oven
cavity, is designed to prevent damage to the oven by fire.

If the food load is overcooked, by either error in cook time
or defect in the control unit, the temperature fuse will open.
Under normal operation, the temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the oven cavity, the temperature fuse will
open at 120˚C, causing the oven to shut down.

The turntable motor drives the turntable roller assembly to
rotate the turntable.

The fan motor drives a blade which draws external cool air.
This cool air is directed through the air vents surrounding
the magnetron and cools the magnetron. This air is chan-
nelled through the oven cavity to remove steam and
vapours given off from heating food. It is then exhausted
through the exhausting air vents at the rear of the oven
cavity.

1. When the timer switch is at "0" position, the switch of

the timer is opened.

2. When the timer is turned clockwise from "0" position,

the switch of the timer is closed.

The noise filter assembly prevents radio frequency inter-
ference that might flow back in the power circuit.

Latch Heads

Latch Hook

Door

Monitored
Latch Switch

Monitor Switch

Switch Lever

Latch Switch

6

CK = Check / RE = Replace

MAGNETRON

HIGH VOLTAGE TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE WIRE

HIGH VOLTAGE CAPACITOR

MONITORED LATCH SWITCH 

LATCH

 SWITCH 

MONITOR SWITCH 

TEMPERATURE FUSE 

TIMER MOTOR

TIMER SWITCH

FAN MOTOR

TURNTABLE MOTOR

FUSE T6.3A

CONTROL UNIT

RELAY (RY-1)

FOIL PATERN ON P.W.B.

POWER SUPPLY CORD

SHORTED WIRE HARNESS

OPENED WIRE HARNESS

OVEN LAMP

WALL OUTLET

MISADJUSTMENT SWITCH

HOME FUSE OR BREAKER

BLOCKED COOLING FAN

BLOCKED VENTILATION

NOISE FILTER

H.V. FUSE

Home fuse blows when power
supply cord is plugged into
wall outlet.

FUSE T6.3A blows when
power supply cord is plugged
into wall outlet.

Oven does not start when the
timer is set.

Oven lamp does not light
(Other function is normal.)

Fan motor does not operate.
(Other function is normal.)

Turntable motor does not op-
erate. (Other function is nor-
mal.)

Oven or any electrical parts
does not stop.

Oven seems to be operating
but little or no heat is produced
in oven load. (Microwave
power level is set at HIGH.)

Oven does not seems to be
operating properly when MED
HIGH, MED, MED LOW or
LOW is set. (Oven operates
properly at HIGH.)

Oven goes into cook cycle but
shuts down before end of cook-
ing cycle.

OFF
CONDITION

PROBLEM

CONDITION

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

TEST PROCEDURE

ON
CONDITION

A B C

CK

D E E E     F K   K   I   I   G   L M N

RE CKCKRECK CKCKCK CK

H J

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 fuse  T6.3A in the monitored latch switch  - timer

switch  - monitor switch circuit, check the monitored latch switch , timer switch and monitor switch  before
replacing the fuse  T6.3A.