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3. If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.

Check them and replace the defective parts and the high voltage fuse.

4. CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE REPLACEMENT.

1. CARRY OUT 3D CHECKS.
2. Disconnect the leads from the terminals of noise filter.

Using an ohmmeter, check between the terminals as described in the
following table.

Between N and L

Approx. 680 k

Ω

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit

If incorrect readings are obtained, replace the noise filter unit.

CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. If the fuse 20A is blown, there is a shorts or grounds in electrical parts or wire harness Check then and replace

the defective parts or repaire the wire harness.

3. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. If the fuse F10A is blown when the door is opened, check the secondary interlock switch, relay RY1, relay

RY2 and monitor switch.

3. If the fuse F10A is blown by incorrect door switching, replace the defective switch(es) and the fuse F10A.
4. If the fuse F10A is blown, there is a shorts or grounds in electrical parts or wire harness.

Check them and replace the defective parts or repair the wire harness.

5. CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE FUSE F10A WITH CORRECT VALUE REPLACEMENT.

FUSE

20A

N

L

LINE CROSS CAPACITOR   1.0

µ/AC275V 

NOISE SUPPRESSION COIL 

LINE BYPASS 
CAPACITOR
0.0047

µ/AC250V

LINE BYPASS
CAPACITOR
0.0047

µ/AC250V

RESISTOR   
10M    1/2W

RESISTOR   680K    1/2W

WHT

RED

NOISE FILTER

1. CARRY OUT 3D CHECKS.
2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the

temperature of the magnetron reaches approximately 150˚C. An open temperature fuse indicates overheating
of the magnetron. Check for restricted air flow to the magnetron, especially the cooling duct and cooling fan.

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE TEMPERATURE FUSE.

1. CARRY OUT 3D CHECKS.
2. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the

temperature of the thermal cut-out reaches approximately 170˚C. The thermal cut-out resets automatically
at approximately 155˚C. If thermal cut-out has opened under normal condition, replace the same item as in
the parts list.
An open thermal cut-out indicates overheating of the top heating element unit. Check for restricted air flow
to the top heat element  unit through the vent holes of the oven cavity, especially the heater duct upper and
convection fan.

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE THERMAL CUT-OUT.

12

1. CARRY OUT 3D CHECKS.
2. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the

temperature of the thermal cut-out reaches approximately 150˚C. The thermal cut-out resets automatically
at approximately 130˚C. If thermal cut-out has opened under normal condition, replace the same item as in
the parts list.
An open thermal cut-out indicates overheating of the side heating element unit. Check for restricted air flow
to the side heat element  unit through the vent holes of the oven cavity, especially the heater duct left and
convection fan.

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE THERMAL CUT-OUT.

1. CARRY OUT 3D CHECKS.
2. Make sure the heating element is fully cooled and test as follows;

a. Disconnect wire leads from the heating element and measure the resistance with an ohmmeter. On the R

x 1 scale, the resistance between the heating element terminals should be approximately 37.2

Ω.

b. Disconnect wire leads from the heating element  and measure the insulation resistance with 500V -

100M

Ω insulation resistance meter. The insulation resistance between heating element terminal and

cavity should be more than 0.5M

Ω.

3. If the meter does not indicate above resistance, replace the top heating element.
4. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Make sure the heating element is fully cooled and test as follows;

a. Disconnect wire leads from the heating element and measure the resistance with an ohmmeter. On the R x 1 scale,

the resistance between the heating element terminals should be approximately 55.7 

Ω.

b. Disconnect wire leads from the heating element  and measure the insulation resistance with 500V -

100M

Ω insulation resistance meter. The insulation resistance between heating element terminal and

cavity should be more than 0.5M

Ω.

3. If the meter does not indicate above resistance, replace the side heating element.
4. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Disconnect connector-E from the control unit. Measure the resistance of the thermistor with an ohmmeter.

Connect the ohmmeter leads to Pin No’s E-5 and E-6.

Room Temperature

Resistance

68˚F(20˚C) - 86˚F(30˚C)

Approx. 360 k

Ω - 152 KΩ

4. If the meter does not indicate above resistance, replace the thermistor.

5. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the temperature

of the  chassis support left reaches approximately 150˚C. An open temperature fuse indicates overheating of
the chassis support left. Check for restricted air flow to the chassis support left, especially the cooling fan.

3. CARRY OUT 4R CHECKS.

CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,

REPLACE TEMPERATURE FUSE.

1. CARRY OUT 3D CHECKS.
2. Disconnect input leads and check for short or open between the terminals using an ohmmeter.

13

Checking with a high ohm scale, if the capacitor is normal, the meter will indicate continuity for a short time
and should indicate an open circuit once the capacitor is charged. If the above is not the case, check the
capacitor with an ohmmeter to see if it is shorted between the terminals. If it is shorted, replace the capacitor.

3. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Disconnect the 3-pin connector of the jet motor from the main wire harness.
4. Measure the resistance of the jet motor with an ohmmeter.

The resistance of the main coil, across the black and the red wires, should be approximately 130 ohms. The
resistance of the sub coil, across the black and the white wires, should be approximately 140 ohms.

5. Also, the jet motor has the thermal cut-out in it.

Measure the resistance of the main coil (or the sub coil). The resistance across the black and the red wires
(or across the black and the white wires) should be
above resistance unless the temperature of the thermal
cut-out reaches approximately 130˚C. The thermal
cut-out resets automatically at 100˚C. If an ohmmeter
indicates an open circuit under normal condition,
replace the jet motor because the thermal cut-out has
opened. An open thermal cut-out indicates overheating
of the jet motor. Check for restricted air flow to the jet
motor or a lock of the convection fan, especially the
fan motor (high voltage transformer side).

6. CARRY OUT 4R CHECKS.

It is difficult to measure the exact temperature in the convection oven. An accurate thermocouple type
temperature tester must be used. A low priced bi-metal type thermometer is not reliable or accurate.
The temperature should be checked with outer case cabinet installed, approx. 5 minutes after preheat
temperature is reached (audible signal sounds four times). The temperature experienced may be approx. 17˚C
more or less than indicated on the display, however, in most cases the food cooking results will be satisfactory.
Difference in power supply voltage will also affect the oven temperature. The Household power supply voltage may
sometimes become lower than the rated voltage and cause under-cooking. If the power supply voltage is 10% lower
than the rated voltage, longer cooking time is required by 10% to 20%.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals

as described in the table below.

Table: Resistance of Motor

Motors

Resistance

Fan motor

Approximately 77 

Ω

Turntable motor

Approximately 12 k

Ω

If incorrect readings are obtained, replace the motor.
4. CARRY OUT 4R CHECKS.

BLK

RED

WHT

Main Coil

3-pin 
Connector

Sub Coil

Thermal

Cut-out

130ßC OFF
100ßC ON

130‰

140‰

JET MOTOR

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike
conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter.
In this service manual, troubleshooting by unit replacement is described according to the symptoms indicated.

1) CARRY OUT 3D CHECKS.
2) Disconnect the leads to the primary of the high voltage transformer.
3) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

14

1.  Tact switches on the CPU unit or the control unit (switch unit)

1) Re-install the outer case (cabinet).

2) Reconnect the power supply cord after the outer case is installed.
3) Run the oven and check all functions.

The following symptoms indicate a defective tact switch.

a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
If the tact switch is defective.
1) CARRY OUT 3D CHECKS.
2) Check which tact switch is defective, one on the CPU unit or one on the control unit (switch unit), referring

to "TACT SWITCH TEST". (Procedure V)

3) Replace the unit that has a defective tact switch.
4) Reconnect all leads removed from components during testing.
5) Re-install the outer case (cabinet).
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions.

2. CPU Unit

The following symptoms  indicate a defective CPU unit.  Reconnect the power supply cord. And  check for
followings.

2-1 In connection with indicators

a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f ) A certain group of indicators do not light up.
g) The figure of all digits flicker.

2-2 Other possible problems caused by defective CPU unit.

a) Cooking is not possible.
b) Proper temperature measurement is not obtained.

3. Other possible problems caused by defective control unit (switch unit).

a) Buzzer does not sound or continues to sound.

4. Other possible problems caused by defective power unit.

a) Cooking is not possible.
b) Electrical parts do not operate.

c) Oven or electrical parts do not stop.

d) Proper temperature measurement is not obtained.

When testing is completed, CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2.  Remove the CPU unit and the control unit (switch unit), referring to "CONTROL PANEL ASSEMBLY, CPU

UNIT AND CONTROL UNIT REMOVAL".

3.  By using an ohmmeter, check the tact switch operation.
4. When the tact switch is not depressed, an ohmmeter should indicate an open circuit. When the tact switch

is depressed, an ohmmeter should indicate a short circuit. If improper operation is indicated, the tact switch
is probably defective.

5. Refer to the switch unit matrix, and judge which unit has any defective tact switches.
6. Replace the CPU unit or the control unit that has any defective tact switches.
7. Assemble the control panel and reinstall it to the oven.
8. CARRY OUT 4R CHECKS.

<CONTROL UNIT (SWITCH UNIT)>

J6

J3

J5

J4

J2

J1

SP1

R11

R10

1.5K 1/4W

3.3K 1/4W

CN-J

10Pin

J7

J8

J10

J9

SW1-10

S10B-PH

START

(SW11)

1

 

11

6 

16

2 

12

7 

17

3 

13

8 

18

4 

14

9 

19

5 

15

0 

20

(SW1)

SPEED

GRILL

SPEED

CONV.

(SW2)

(SW3)

(SW6)

(SW5)

(SW4)

(SW7)

(SW10)

(SW8)

(SW9)

SET

PAUSE

CHECK

OVEN

(˚C)

HOLD

150˚C

MICRO-

WAVE

MANUAL
REPEAT

WH-A

SW11-23

(SW12) (SW13)

(SW14)

(SW18)

(SW17)

(SW16)

(SW15)

(SW22)

(SW21)

(SW20)

(SW19)

(SW23)

STOP

CLEAR