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1. Control panel

2. Door lock openings

3. Tray

4. Splash cover

5. Oven lamp

6. Air intake filter

7. Air intake openings

8. Oven cavity

9. Door seals and sealing surfaces

10. Door hinges

11.  Door

12. Safety door latches

13. Door open handle.

14. Outer cabinet

15. Oven lamp access cover

16. Ventilation openings

17.  Power supply cord

18 Mounting plate

19 Screw for mounting plate

DISPLAY AND INDICATORS
Check indicators after the oven starts to

confirm the oven is operating as de-
sired.

1.

Cook indicator

This indicator shows cooking in progress.

2.

Digital display

3.

Microwave power level indicator

4.

Power 100%

5.

Power 50%

6.

Power 20%

7.

Power 10%

8.

ELECTRIC TIMER

Rotate the knob to enter cooking time.

9.

START button

1

2

3

4

5

7

6

8

9

10

11

12

13

15

16

14

18

19

17

MICROWAVE POWER
LEVEL button

2
1

3

4

5

6

7

8

9

/100%

/ 50%

/ 20%

/ 10%

4

Closing the door activates all door interlock switches
(1st latch switch, 2nd latch switch, 3rd latch switch and stop
switch)

IMPORTANT
When the oven door is closed, the monitor switch contacts
COM-NC must be open. When the microwave oven is
plunged in a wall outlet (230  volts, 50Hz), the line voltage is
supplied to the point A5+A7 in the control panel.

1. The digital display shows      .
NOTE: When the door is opened or after cooking, oven

lamp, blower motor and stirrer motors work for 1
minute.

Enter a desired cooking time with the turning ELECTRIC
TIMER knob. And then push START button.

CONNECTED COMPONENTS

RELAY

Oven lamp/ Blower motor/ Stirrer motors

RY1

Power transformer T1

RY3

Power transformer T2

RY4

1. The line 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 mag-

netron 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 channelled 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 RY3+RY4 go back to their home position. The
circuits to the high voltage transformers T1+T2. The
relay RY1 remains and oven lamp, blower motor and
stirrer motors work for 1 minute.

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 latch switch

COM-NO

Closed

  Open

Monitor switch

COM-NC

Open

  Closed

2nd latch switch

COM-NO

Closed

  Open

Stop switch

COM-NO

Closed

  Open

3rd latch switch

COM-NO

Closed

  Open

The circuits to the high voltage transformers T1+T2 are
cut off when the 1st latch, 2nd latch, 3rd latch and stop
switches  SW1+SW2+SW3+SW5 are made open. The
blower motor BM, stirrer motors and 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, but
the program is cancelled if the oven is not started within
3 minutes.

6. MONITOR SWITCH CIRCUIT

The monitor switch SW4 is mechanically controlled by
oven door, and monitors the operation of the 1st latch
switch SW1.

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

of a cooking program, the 1st, 2nd, 3rd latch and stop
switches SW1+SW2+SW3+SW5 must open their con-
tacts first. After that the contacts (COM-NC) of the
monitor switch SW4 can be closed.

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

of the monitor switch SW4 must be opened first. After
that the contacts (COM-NO)of the 1st, 2nd, 3rd latch
and stop switches SW1+SW2+SW3+SW5 must be
closed.

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

1st latch switch SW1 remain closed, remains closed,
the fuse F2 F6.3A will blow, because the monitor switch
is closed and a short circuit is caused.

When the microwave oven is preset for variable cooking
power, the line voltage is supplied to the high voltage
transformers T1+T2 intermittently within a 48 second time
base through the contacts of the relays RY3+RY4.
The following levels of microwaves power are given.

48 sec. ON

100%

26sec. ON

50%

12 sec. ON

20%

8 sec. ON

10%

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

spond to the percentage of microwave power, be-
cause approx. 3 seconds are needed for heating up
the magnetron filament.

Two magnetrons MG1+MG2 are equipped in order to get
higher microwave power output. The primary windings of the
high voltage transformers T1+T2 are connected so that each

5

The monitor switch is activated (the contacts opened) the
upper latch head and switch lever A while the door is
closed. The switch is intended to render the oven inopera-
tive by means of blowing the fuse F2 F6.3A when the
contacts of the 1st latch switch SW1 fail to open when the
door is opened.

Function
1. When the door is opened, the monitor switch SW4

contacts close (to the ON condition) due to their being
normally closed. At this time the 1st latch switch  SW1
is 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 opened and 1st latch switch con-
tacts are closed (On opening the door, each of these
switches operate inversely.)

3. If the door is opened and the 1st latch switch contacts

fail to open, the fuse F2 F6.3A blows simultaneously
with closing of the monitor switch contacts.

CAUTION:BEFORE REPLACING A BLOWN FUSE F2

F6.3A TEST THE 1ST LATCH SWITCH,
MONITOR SWITCH AND MONITOR RESIS-
TOR FOR PROPER OPERATION. (REFER
TO CHAPTER “TEST PROCEDURE”).

The monitor resistor prevents the fuse F2 F6.3A 250V
bursting when the fuse F2 F6.3A 250V blows due to the
operation of the monitor switch.

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

If the wire harness or electrical components make a short-
circuit, this weak point/ Fuse F1 blows to prevent an
electric shock or fire hazard.

1. The door release lever is pulled.
2. The upper latch head is lifted up by the linked door

release lever.

3. The latch lever is lifted up by the door release lever.
4. The joint lever is lifted up by the latch lever.
5. The lower latch head is lifted up by the joint lever.
6. Now both latch heads are lifted up, so they can be

released from the latch hook.

7. Now the door can be opened.

Latch head

Monitor switch

Latch hook

1st. latch switch

2nd. latch switch

Stop switch

3rd. latch switch

Latch head

Joint lever

Door release
lever

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.

COMMERCIAL
FREQUENCY
(50HZ)

POWER OUTPUT
BY MAGNETRON 1

POWER OUTPUT
BY MAGNETRON 2

OPERATION OF
MAGNETRON

magnetron can be oscillated alternatively according to the

frequency of the power supply. Refer to the Figure 1 and 2.

T1: HIGH VOLTAGE
      TRANSFORMER

ASYMMETRIC

RECTIFIER

 H. V. RECTIFIER

C1: H.V. CAPACITOR

MG1: MAGNETRON (UPPER)

(REAR)

ASYMMETRIC

RECTIFIER

 H. V. RECTIFIER

C2: H.V. CAPACITOR

MG2: MAGNETRON (LOWER)

T2: HIGH VOLTAGE
      TRANSFORMER

(FRONT)

6

The air temperature around the lower magnetron is
detected through the resistance of the thermistor.
If the temperature is high, the control panel will display
"EE17" and the oven will stop to protect the lower magn-
etron against overheat.
If the thermistor is open, the control panel will display
"EE16" and the oven will stop.

These thermal cut-outs protect the magnetrons against
overheat. If their temperature go up higher than 145˚C
because the blower motor is interrupted, the ventilation
openings are blocked, the thermal cut-outs TC1+TC2 will
open and the line voltage to the high voltage transformer
T1+T2 will be cut off and the operations of the magnetrons
MG1+MG2 will be stopped. The defective thermal cut-out
must be replaced with new rated one.

This thermal cut-out protect the blower motor against
overheat. If its temperature goes up higher than 115˚C
because the blower motor is locked or the ventilation
openings are blocked, the contacts of the thermal cut-out
TC3 will open and the line voltage to the control unit will
be cut off and the operation of the oven will be stopped.
The defective thermal cut-out must be replaced with new
rated one.

This 

thermal cut-out

 protects the oven against overheat. If

the temperature goes up higher than 115˚C because the
food catches fire, the contacts of 

thermal cut-out

 will open

and the line voltage to the control unit will be cut off and the
operation of the oven will be stopped. The defective 

thermal

cut-out

 must be replaced with a new rated one.

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

The stirrer motor drives a stirrer antenna to stir the
microwave radiation from the waveguide.

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

circuited, this fuse blows to prevent an electric shock
or fire hazard.

2. The fuse also blows when 1st latch switch SW1

remains closed with the oven door open and when the
monitor switch SW4 closes.

The asymmetric rectifier is solid state device that pre-
vents current flow is both directions. And it prevents the
temperature rise of the high voltage transformer by
blowing the weak point / fuse WP1 or WP2 when the high
voltage rectifier is shorted.

The rated peak reverse voltage of D1 of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2 of
the asymmetric rectifier is 1.7 KV. D1 and D2 of the
asymmetric rectifier or high voltage rectifier are shorted
when the each peak reverse voltage goes beyond the
each rated peak reverse voltage. (The process of the
blowing the weak point / fuse WP1 or WP2)
1. The high voltage rectifier is shorted by some fault

when microwave cooking.

2. The peak reverse voltage of D2 of the rectifier goes

beyond the rated peak reverse voltage 1.7 KV in the
voltage doubler circuit.

3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high

voltage winding of the high voltage transformer.

5. The large electric currents flow through the primary

winding of the high voltage transformer.

6. The weak point/ fuse WP1 or WP2 blows by the large

electric currents.

7. The power supplying to the high voltage transformer

is cut off.

The thermistor is a negative temperature coefficient type.
The temperature in the exhaust duct is detected through
the resistance of the thermistor.
If the temperature is high, the control panel will display
“EE7” and the oven will stop to avoid overheating and
catching fire.
If the thermistor is open, the control panel will display
"EE6" and the oven will stop.

This thermistor detects ambient air temperature.