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1. DIGITAL DISPLAY
2. INDICATORS
3. EXPRESS COOK Key
4. EXPRESS DEFROST Key
5. TIME Keys
6. START/AUTO MINUTE Key
7. STOP/CLEAR Key
8. POWER/WEIGHT Key

6. Door seals sealing surfaces
7. Coupling
8. Control panel
9. Liquid crystal display

10. Waveguide cover

1. Door open button
2. Oven lamp
3. Door hinges
4. Door safety latches
5. See through door

11. Power supply cord
12. Ventilation openings
13. Turntable
14. Roller stay

8

1

9

14

10 4

2

4

3

5

6

7

13

11

12

3

4

7
8

5

6

2

1

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 flashes "88:88".
2. To set any programmes or set the clock, you must first

touch the STOP/CLEAR key.

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 touching the TIME keys
and start the oven with touching START key.

CONNECTED COMPONENTS

RELAY

Oven lamp, Fan motor, 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 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 RY1+RY2 go back to their home position.
The circuits to the oven lamp, high voltage transformer,
fan motor 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. latch 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 motor
turntable motor and oven lamp are cut off when the 1st.
latch switch and 2nd. interlock relay control switch are
made open.

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. latch switch
and 2nd. interlock relay.

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

cycle of a cooking program, the 1st. latch 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. latch switch and 2nd. interlock
relay control switch are closed.

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

the 1st latch switch and 2nd. interlock relay remain
closed. The fuse T6.3A will blow, because the moni-
tor 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.

If the oven set for more than 20 minutes at 100% power
level, after the first 20 minutes the power level will automati-
cally adjust itself to 70% power to avoid overcooking.

100P

32 sec. ON

70P

Approx. 70%

100%

24 sec. ON

8 sec. OFF

14 sec. OFF

20 sec. OFF

26 sec. OFF

50P

Approx. 50%

18 sec. ON

30P

Approx. 30%

12 sec. ON

10P

Approx. 10%

6 sec. ON

5

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 248˚F(120˚C), causing the oven to shut down.

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

The turntable motor drives the roller stay 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
channelled through the oven cavity to remove steam and
vapours given off from the heating foods. It is then ex-
hausted through the exhausting air vents at the oven
cavity.

1. When the oven is switched on at microwave cooking,

at first the contacts of the surge relay is open and the
surge current flows through the surge resistor RS.

2. And then after a few msec., the contacts of the surge

relay RY1 are closed and rated voltage are supplied to
the high voltage transformer.

3. The surge resistor RS lets the current (peak current)

flow when the oven is switched on. If the surge resistor
is defective, the home fuse or monitor fuse may break
down when the oven is switched on (microwave mode).

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.

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 latch switch and 2nd. interlock relay fail to
open, the fuse blows simultaneously with closing the
contacts (COM-NC) of the monitor switch.

CAUTION: BEFORE REPLACING A FUSE TEST THE

1ST LATCH SWITCH, 2ND. INTERLOCK
RELAY AND MONITOR SWITCH FOR
PROPER OPERATION. (REFER TO CHAP-
TER "TEST PROCEDURE".)

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

latch switch, 2nd. interlock relay remain closed with the
oven door open and when the monitor switch  closes.

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

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

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

Latch Heads

Latch Hook

Door

2nd. Interlock Relay
Control Switch

Monitor Switch

Switch Lever

1st. Latch Switch

6

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 1st. latch switch - 2nd. interlock

relay  - monitor switch circuit, check the 1st. latch switch, 2nd. interlock relay control switch, 2nd. interlock
relay and monitor switch before replacing the fuse T6.3A.

CK = Check / RE = Replace

MAGNETRON

HIGH VOLTAGE  TRANSFORMER

HIGH VOLTAGE RECTIFIER ASSEMBLY

HIGH VOLTAGE WIRE

HIGH VOLTAGE CAPACITOR

1ST. LATCH SWITCH

2ND

. INTERLOCK RELAY CONTROL

 SWITCH

MONITOR SWITCH

TEMPERATURE FUSE (OVEN)

FAN MOTOR

TURNTABLE MOTOR

FUSE T6.3A

TOUCH CONTROL PANEL

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

KEY UNIT (MEMBRANE SWITCH)

H.V. FUSE

SURGE RELAY

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.

"88:88" does not appear in dis-
play but power supply cord is
plugged into wall outlet.

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

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 does not oper-
ate. (Display appears.)

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 100%)

Oven does not seems to be
operating properly when 70%,
50%, 30% or 10% is set.

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  G  G   H   K M N

RE CKCKRECK CKCKCKCK

I L J

CK