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3

1 Door opening handle
2 Control panel
3 Digital display
4 See through door
7 Door latches
6 Door hinges
7 Door seals and sealing surfaces
8 Coupling
9 Oven cavity
10 Oven lamp
11 Waveguide cover
12 Ventilation openings
13 Outer case cabinet
14 Power cord
15 Turntable
16 Turntable support

1. EXPRESS COOK keys

Use to cook 7 popular foods.

2. EXPRESS DEFROST keys

Use to defrost 3 popular foods.

3. INSTANT COOK keys

Use to cook 4 popular foods. menus. (See NOTE.)

4. DIGITAL DISPLAY
5. WEIGHT CONVERSION key

Use to change weight, e.g. Kg/g to Lb/oz.

6. KITCHEN TIMER key

Press to use as a minute timer, or to programme
standing time.

7. TIME key

Use to enter clocking time.

8. POWER LEVEL key

Press to select microwave power level.

9. START/ AUTO MINUTE key

Press to start a programme. Press to cook on 100P for
1 minute on or increase time during cooking in multiples
of 1 minute. (See NOTE.)

10.STOP/CLEAR key

Press once to stop a programme, twice to cancel a
programme.

11.LESS/ MORE keys

Press to shorten/ lengthen cooking time.

12.WEIGHT keys

Press up or down to select correct weight/ number of
pieces.
When the minimum (or maximum) weight/ number is
reached, the display will not change, even if you
continue to press the DOWN (or UP) key.

13.CLOCK SET key

Use to set the clock or display the time.

14.DELAY START key

Use to programme DELAY START.

4

Closing the door activates all door interlock switches
(1st. latch switch, 2nd. interlock relay control switch).

IMPORTANT
When the oven door is closed, the monitor switch contacts
(COM-NC) 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.

1. The display will show flashing "88:88".
2. To set any programmes or set the clock, you must

first touch the STOP/CLEAR pad.

3.        :        appears in the display.

NOTE: When the oven door is opened, the oven lamp

comes on at this time.

HIGH COOKING
Enter a desired cooking time with the touching TIME keys
and start the oven with touching STARTkey.

CONNECTED COMPONENTS

RELAY

Oven lamp, Fan motors, Turntable motor

RY1

High voltage transformer

RY2

1. 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.

2. 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..

3. The 2450 MHz microwave energy produced in the

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

4. When the cooking time is up, a signal tone is heard and

the relays RY1+RY2 go back to their home position.
The circuits to the oven lamp, high voltage transformer,
fan motors and turntable motor are cut off.

5. When the door is opened during a cook cycle, the

switches come to the following condition

CONDITION
DURING

DOOR OPEN

SWITCH

CONTACT

COOKING

(NO COOKING)

1st. interlock switch

COM-NO

Closed

  Open

2nd. interlock relay
control switch

COM-NO

Closed

  Open

Monitor switch

COM-NC

Open

  Closed

The circuits to the high voltage transformer, fan motors
and turntable motor are cut off when the 1st. interlock
switch  and 2nd. interlock relay control switch are made
open. The oven lamp remains on even if the oven door

is opened after the cooking cycle has been interrupted,
because the relay RY1 stays closed. Shown in the
display is the remaining time.

6.

MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by
oven door, and monitors the operation of the 1st.
interlock switch and the relay RY1.

6-1 When the oven door is opened during or after the

cycle of a cooking program, the 1st. interlock switch
and 2nd. interlock relay control switch must open their
contacts first.
After that the contacts (COM-NC) of the monitor
switch can be closed.

6-2. When the oven door is closed, the contacts (COM-

NC) of the monitor switch must be opened. After that
the contacts of the 1st. interlock switch and 2nd.
interlock relay control switch are closed.

6-3. When the oven door is opened and the contacts of

the1st. interlock switch and the relay RY1 remain
closed, the fuse F10A 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 power transformer
intermittently within a 32-second time base through the
relay contact which is coupled with the current-limiting
relay RY2. The following levels of microwave power are
given.

SETTING;

NOTE: The ON/OFF time ratio does not exactly correspond

to the percentage of microwave power, because
approx. 3 seconds are needed for heating up the
magnetron filament.

After 100% power cooking mode is carried out for more
than 40 minutes, the power out-put is automatically re-
duced to 70%.  Even if the cooking time is shorter than for
40 minutes, the power output is reduced to 70% after total
cooking time over 40 minutes when the oven is started in
100% power cooking mode again within 1 minute and 35
seconds.

100P (HIGH)

32 sec. ON

70P (MEDIUM 

HIGH)

Approx. 70%

100%

24 sec. ON

8 sec. OFF

14 sec. OFF

20 sec. OFF

26 sec. OFF

50P (MEDIUM)

Approx. 50%

18 sec. ON

30P (MEDIUM 

LOW)

Approx. 30%

12 sec. ON

10P (LOW)

Approx. 10%

6 sec. ON

5

The thermal cut-out, located on the top of the oven cavity,
is designed to prevent damage to the oven by fire. If the
foods load is overcooked, by either error in cook time or
defect in the control unit, the thermal cut-out will open.
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 125˚C, causing the oven to shut down. The
defective thermal cut-out must be replaced with new one.

The thermal cut-out located near the magnetron is de-
signed to prevent damage to the magnetron if an over
heated condition develops in the tube due to cooling fan
failure, obstructed air guide, dirty or blocked air intake, etc.
Under normal operation, the thermal cut-out remains
closed. However, when abnormally high temperatures are
reached within the magnetron, the thermal cut-out will
open at 125˚C causing the oven to shut down.  The
defective thermal cut-out must be replaced with new one.

The thermostat protects the high voltage transformer
against over heating. If the temperature goes up higher
than 150˚C because the fan motor is interrupted or the
ventilation openings are blocked, the thermostat will cycle,
line voltage to the high voltage transformer will also cycle.
(If operated, check the magnetron for damage.)

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
channeled through the oven cavity to remove steam and
vapors given off from the heating foods. It is then ex-
hausted through the exhausting air vents at the oven
cavity

The noise filter prevents the radio frequency interference
that might flow back in the power circuit.

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

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

must be closed.

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

NO) must be opened.

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 the contacts (COM-NO)

of the 1st. interlock switch and the relay RY1 fail to
open, the fuse F10A blows  simultaneously with closing
the contacts (COM-NC) of the monitor switch.

CAUTION: BEFORE REPLACING A BLOWN FUSE

F10A TEST THE 1ST. INTERLOCK SWITCH,
RELAY  RY1, MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OP-
ERATION.

Ω

The monitor resistor prevents the fuse F10A bursting
when the fuse F10A blows due to the operation of the
monitor switch.

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

1. The fuse F10A blows when the contacts (COM-NO) of

the 1st. interlock switch and the relay RY1 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 fuse F10A blows to prevent an electric
shock or fire hazard.

Latch 
Heads

Door

Latch Hook

2nd. Interlock
Relay Control 
Switch

1st. Interlock
 Switch

Monitor Switch

6

CK = Check / RE = Replace

MAGNETRON

HIGH VOLTAGE TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE CAPACITOR

1ST. INTERLOCK SWITCH

2ND.INTERLOCK RELAY

CONTROL SWITCH

MONITOR SWITCH

MONITOR RESISTOR

THERMAL CUT-OUT 125

˚C

FAN MOTOR

TURNTABLE MOTOR

FUSE F10A

TOUCH CONTROL PANEL

KEY UNIT

RELAY (RY-1, RY-2)

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

HIGH VOLTAGE FUSE

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

FUSE F10A blows when
power supply cord is plugged
into wall outlet.

Display does not show any-
thing when power supply cord
is plugged into wall outlet.

Display  does not operate prop-
erly when STOP/CLEAR key
is touched.

Oven lamp does not light at
door opened. (Display ap-
pears.)

Oven does not start when the
START key is touched.  (Dis-
play appears)

Oven lamp does not light (Dis-
play appears.)

Fan motor does not operate.
(Display appears.)

Turntable motor assembly
does not operate. (Display ap-
pears.)

Oven or any electrical parts
does not stop when cooking
time is 0 or STOP/CLEAR key
is touched.

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 70%,
50%, 30% or 10% is set. (Oven
operates properly at 100%
power and when the STOP/
CLEAR key is touched the
oven stops.)

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

TEST PROCEDURE

A B C D E

E

E G F H   H I L M N O

 RE CK CK RE CK CKCK CK CK

J K

CONDITION

PROBLEM

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

ON
CONDITION

OFF
CONDITION

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 F10A in the 1st. interlock switch - relay RY1

- monitor switch - monitor resistor circuit, check the 1st. interlock switch, relay RY1, monitor switch and
monitor resistor before replacing the fuse F10A.