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9

CARRY OUT 

4. 

4R CHECKS.

CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested using an ohmmeter set to its 

highest range. Connect the ohmmeter across the terminal of the high voltage rectifier and note the reading obtained. Reverse the me -

ter leads and note this second reading. The normal resistance is infinite in one direction and more than 100 kW in the other direction.
CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Isolate the high voltage capacitor from the circuit.

1. 

Continuity check must be carried out with measuring instrument which is set to the highest resistance range.

2. 

A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MW after it has been charged.

3. 

A short -circuited capacitor shows continuity all the time.

4. 

An open capacitor constantly shows a resistance about 10 MW because of its internal 10MW resistance.

5. 

When the internal wire is opened in the high voltage capacitor shows an infinite resistance.

6. 

The resistance across all the terminals and the chassis must be infinite when the capacitor is normal.

7. 

If incorrect reading are obtained, the high voltage capacitor must be replaced.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table.

Released

Open circuit

Short circuit 

Depressed

Short circuit 

Open circuit.

If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the temperature fuse. Then using an ohmmeter, make a continuity test across the two ter -
minals as described in the below.

Parts Name

Temperature of "ON" condition 

(Closed circuit).

Temperature of "OFF" condition 

(Open circuit).

Indication of ohmmeter 

(When room temperature is approx. 20°C.)

Temperature fuse 150°C

This is not resetable type.

Above 150°C

Closed circuit

If incorrect readings are obtained, replace the temperature fuse.
An open circuit temperature fuse (OVEN) indicates that the food in the oven cavity may catch fire, this may be due to overheating pro -

duced by improper setting of the cooking time or failure of the control panel.
CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.
Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals as described in the table 
below.

Fan motor

Approximately 250 W

Turntable motor

Approximately 14.7 kW

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

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10

CARRY OUT 3D CHECKS.
If the fuse T6.3A is blown when the door is opened, check the 1st. latch switch, relay (RY1), 2nd. interlock relay (RY2) and monitor 
switch.

If the fuse T6.3A is blown by incorrect door switching replace the defective switch(es) and the fuse T6.3A.
If the fuse T6.3A 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.

CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE FUSE T6.3A WITH THE CORRECT VALUE REPLACEMENT.

CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the noise filter. Using an ohmme -

ter, check between the terminals as described in the following table. 

Between N and L 

Open circuit

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.

CARRY OUT 3D CHECKS.
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.
CARRY OUT 4R CHECKS.

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

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, the touch control panel 
assembly is divided into two units, Control Unit and Switch Unit, and also the Control Unit is divided into two units, CPU Unit and Pow -
er Unit, and troubleshooting by unit replacement is described according to the symptoms indicated.

1.  Switch Unit. Note: Check switch unit wire harness connection before replacement. 

 

The following symptoms indicate a defective switch unit. Replace the switch unit.

a)  When touching the buttons, a certain button produces no signal at all.

b)  When touching the buttons, sometimes a button produces no signal.
c)  When rotating the TIMER/WEIGHT knob, the cooking time or the weight can not be input.

2.  Control Unit.

 

The following symptoms indicate a defective control unit. Before replacing the switch unit, perform the Switch unit test (Procedure L) 
to determine if control unit is faulty. 

2 -1.  In connection with buttons.

a)  When touching the buttons, a certain group of buttons do not produce a signal. 

b)  When touching the buttons, no buttons produce a signal.

2 -2.  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 up. 

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.

3.  Other possible troubles caused by defective control unit.

a)  Buzzer does not sound or continues to sound.
b)  Clock does not operate properly.
c)  Cooking is not possible.

RED

WHT

FUSE
T6.3A

N

L

NOISE SUPPRESSION COIL 

NOISE FILTER

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11

CARRY OUT 

1. 

3D CHECKS.

Isolate the switch unit with the control panel frame to be tested.

2. 

Using an ohmmeter and referring to the switch unit matrix indicated on the switch unit circuit, check the circuit between the pins of 

3. 

the switch unit that correspond to the STOP button. When the button is pressed, the ohmmeter should indicate short circuit. When 
the button is released, the ohmmeter should indicate open circuit. If incorrect readings are obtained, the switch unit button is faulty 
and must be replaced. About the other buttons, the above method may be used.

CARRY OUT 

4. 

4R CHECKS.

A-3

A-4

A-5

A-6

B-2

B-3

A-1

A

B

C

SW100

A-2

C100

C101

R100

R101

A-7

B-1

C-1

C-2

C-3

3PIN

WIRE 

HARNESS

SWITCH UNIT

EXPRESS

COOK

MEAT

JOINT

TIME

WEIGHT

MINCED

MEAT

WHOLE

POULTRY

POWER

LEVEL

STOP

CLEAR

START

AUTO

MINUTE

SW1

SW2

SW3

SW4

SW5

SW6

SW7

CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between the upper side terminal of the relay RY1 and the oven side terminal of the relay 

RY2 on the control unit with an A.C. voltmeter. The meter should indicate 230 - 240 volts, if not check oven circuit.

These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.

DC. voltage indicated .................. Defective relay.

DC. voltage not indicated ............

Check diode which is connected to the relay coil. If diode is good, control unit is defective.

RY1

Approx. 12.6V D.C.

Oven lamp / Turntable motor / Cooling fan motor

RY2

Approx. 12.1V D.C.

High voltage transformer

CARRY OUT 4R CHECKS.

To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the PWB, this foil pattern acts 
as a fuse. If the foil pattern is open, follow the troubleshooting guide given below for repair.

Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

1

The rated AC voltage is not present between the upper side terminal of 
the relay RY1 and the oven side terminal of the relay RY2.

Check supply voltage and oven power cord.

2

The rated AC voltage is present to primary side of low voltage transformer.

Low voltage transformer or secondary circuit defective.

Check and repair.

3

Only pattern at "a" is broken.

*Insert jumper wire J1 and solder.

4

Pattern at "a" and "b" are broken.

*Insert the coil RCILF2003YAZZ between "c" and "d".

CARRY OUT 4R CHECKS.

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12

The touch control section consists of the following units as shown in the touch control panel circuit.

(1) Switch Unit

(2) Control Unit

The principal functions of these units and their related signals are explained below.

The  switch  unit  is  composed  of  a  matrix,  signals  generated  in  the  LSI  are  sent  to  the  switch  unit  through  P22,  P24,  P25  and  P26. 
When a button is pressed, a signal is completed through the switch unit and passed back to the LSI through P50 and P52 to perform 
the function that was requested. When the jog dial is rotated, the encoder converts the signal from the power source circuit into the 
pulse signal, and the pulse signal is sent to the LSI through P31 and P32.

Control unit consists of LSI, reset circuit, indicator circuit, power source circuit, relay circuit, buzzer circuit and synchronizing signal cir -
cuit. 

1)  Reset Circuit

 

This circuit generates a signal which resets the LSI to the initial state when power is supplied.

2)  Indicator Circuit

 

This circuit consists of 4 -digits, 12 -segments and 3 -common electrodes using a Liquid Crystal Display.

3)  Power Source Circuit
 

This circuit generates voltage necessary in the control unit from the AC line voltage. In addition, the synchronizing signal is 

available in order to compose a basic standard time in the clock circuit.

 

Symbol 

Voltage 

Application

 

VSS 

 -5V 

LSI(IC1) 

4)  Relay Circuit

 

To drive the magnetron, fan motor, turntable motor and light the oven lamp.

5)  Buzzer Circuit
 

The buzzer is responsive to signals from the LSI to emit audible sounds (switch unit touch sound and completion sound).

6)  Synchronizing Signal Circuit
 

The power source synchronizing signal is available in order to compose a basic standard time in the clock circuit. It accompanies 

a very small error because it works on commercial frequency.

7)  2nd. Interlock Relay Control Switch
 

A switch to "tell" the LSI if the door is open or closed.

8)  Back Light Circuit
 

A circuit to drive the back light (Light emitting diodes LD1 - LD4).

This  unit  uses  CMOS  LSI  in  the  integral  part  of  the  circuits. 
When  handling  these  parts,  the  following  precautions  should 
be strictly followed. CMOS LSI have extremely high impedance 
at its input and output terminals. For this reason, it is easily in -
fluenced by the surrounding high voltage power source, static 
electricity  charge  in  clothes,  etc.,  and  sometimes  it  is  not  fully 
protected by the built -in protection circuit.

In order to protect CMOS LSI.

1)  When  storing  and  transporting,  thoroughly  wrap  them  in 

aluminium  foil. Also  wrap  PW  boards  containing  them  in 
aluminium foil.

2)  When  soldering,  ground  the  technician  as  shown  in  the 

figure and use grounded soldering iron and work table.

approx. 1M ohm

We  describe  the  procedures  to  permit  servicing  of  the  touch 
control  panel  of  the  microwave  oven  and  the  precautions  you 
must take when doing so. To perform the servicing, power to the 
touch control panel is available either from the power line of the 
oven itself or from an external power source.

CAUTION: THE HIGH VOLTAGE TRANSFORMER OF THE MI -

CROWAVE OVEN IS STILL LIVE DURING SERVIC -
ING AND PRESENTS A HAZARD. 

 

Therefore, before checking the performance of the touch 
control panel, 

(1)  Disconnect  the  power  supply  cord  and  then  remove 

outer case.

(2)  Open the door and block it open.
 

Discharge high voltage capacitor.

(3)  Disconnect  the  leads  to  the  primary  of  the  power 

transformer.

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