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15

Resistance of Blower motor should be approximately 52

Ω

.

Resistance of Stirrer motor should be approximately 8.8 k

Ω

.

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

L (min)

Cx 

±

 20%

Cy 

±

 20%

0.5mH

0.22 

µ

F

4700 pF

Between N and L

Open circuit

Between terminal N and WHITW

Short circuit

Between terminal L and BLK

Short circuit

If incorrect readings are absorbed, replace the noise filter.

CARRY OUT 4R CHECKS

L

N

L

L

F1

Cy

BLK

WHT

Cx

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of noise filter. Using an ohmmeter, check between the
terminals as described in the following table.

The touch control panel consists of circuits including semiconductors such as LSI 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,  troubleshooting by unit replacement is described according to
the symptoms indicated.
1. Switch Unit

The following symptoms indicate a defective switch unit. Replace the switch unit.
a) When touching the select buttons, a certain button produces no signal at all.
b) When touching the select buttons, sometimes a button produces no signal.

2. Control Unit

The following symptoms may indicate a defective control unit. Replacing the control unit.

2-1 Programming problems.

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

2-2 Display problems.

a) For a certain digit, all or some segments do not light up.
b) For 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.

2-3 Other possible problems caused by defective control unit.

a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.

Note:

When defective components, (the Control Unit or Switch Unit) are replaed, the defective part
or parts must be properly packed for return in the shipping carton. with its cushion material,
in which the new replacement part was shipped to you.

16

1. CARRY OUT 3D CHECKS.
2. Remove the switch unit from the control panel, referring to control panel removal.
3. To test the switches (SW1-SW5) on the switch unit, check between the terminals of the connector

CN-F as described in the following table by using ohmmeter when the switches are released and
depressed.

SW1

F1 - F4

O.C.

S.C.

SW2

F1 - F5

O.C.

S.C.

SW3

F2 - F4

O.C.

S.C.

SW4

F2 - F5

O.C.

S.C.

SW5

F3 - F4

O.C.

S.C.

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.

STEPS

OCCURANCE

CAUSE OR CORRECTION

1

The rated AC voltage is not present at

Check supply voltage and oven power cord.

POWER terminal of CPU connector (CN-A)

2

The rated AC voltage is present at primary

Low voltage transformer or secondary circuit defective.

side of low voltage transformer.

Check and repair.

3

Only pattern at "a" is broken.

*Insert jumper wire J9 and solder.

(CARRY OUT 3D CHECKS BEFORE REPAIR)

4

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

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

(CARRY OUT 3D CHECKS BEFORE REPAIR)

O.C. : Open Circuit

S.C. : Short Circuit

CARRY OUT 3D CHECKS.

Remove the outer case and  check voltage between Pin Nos. 5 and 7 of the  connector (A) on the
control unit with an A.C. voltmeter. The meter should indicate 230 volts, if not check control unit
circuity.

RY1, RY2 and RY3 Relay Test
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. 18.0V D.C.

Oven lamp,Blower motor and Stirrer motor

RY2

APPROX. 17.5V D.C.

Power transformer 1

RY3

APPROX. 17.5V D.C.

Power transformer 2

 CARRY OUT 4R CHECKS.

17

S1

S2

2

3

P

TI

C31

D23

+

–

VRS1

(J9)

(J8)

OL, BM

POWER

7

5

3

1

D21

CN–A

NOTE: *At the time of these repairs, make a

visual inspection of the varistor for
burning damage and examine the
transformer with tester for the
presence of layer short-circuit (check
primary coil resistance). If any
abnormal condition is detected,
replace the defective parts.

CARRY OUT 4R CHECKS.

18

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

(1) Control Unit
(2) Key Unit

The principal functions of these units and the signals
communicated among them are explained below.

Signal of key touch and oven function control are all
processed by one microcomputer.

This circuit changes output voltage at the secondary
side of the low voltage (T1) transformer to volatges
required at each part by full wave rectifying circuit,
constant voltage circuit, etc..

This is an Auto-clear Circuit, i.e., a reset circuit, which
enables IC1 to be activated from initial state.

This is a circuit for generating power SYNC signal by
virtue of the secondary side output of transformer T1.
This signal is used for a basic frequency to time
processing and so on.

This is a circuit for controlling clock frequency required
for operating IC1.

This is a one-chip microcomputer, responsible for
controlling the entire control unit.

This is a circuit for driving display tubes by IC1 output.

This is a circuit for transmitting switch input informa-
tion to IC1.

This is a circuit for driving sound body by IC1 output.

This is a circuit for driving output relay by IC1 output.

This is a circuit for driving IC1 to detect door opening/
closing.

This is a circuit for transmitting output change of

OUTLINE OF CONTROL PANEL

thermistor (Exhaust Air Temperature Sensor) to IC1.

This circuit detects problems in the magnetron / high
voltage circuit by sensing a variation in the current
flowing through the primary winding of the high voltage
transformer.
During heating, the primary current of the high voltage
transformers also flows through the primary winding of
the current transformers CT1 and CT2. This causes a
current to be induced in the secondary windings of
CT1/CT2 and results in an AC voltage  which is
determined by R30/R31.
This AC voltage is then half wave rectified by D30/D31
and smoothed (filtered) by C30/C31.
This AC voltage is the input to the AN3 and AN4 ports
of IC1, which determines if there is a magnetron / high
voltage problem.

HIGH VOLTAGE TRANSFORMER

HIGH VOLTAGE CIRCUIT
MAIN BODY SIDE

T/C SIDE

CT1 or CT2

RY2 or RY3

R30 or
R31

R65 or
R66

D30 or
D31

R32 or
R33

Vc

C30 or C31

IC1
AN3 or
AN4 PORT

D32 or
D33

This is a circuit for transmitting output change of
thermistor (Magnetron Temperature Sensor) to IC1.

This is a circuit for transmitting output change of
thermistor (Intake Air Sensor) to IC1.

The switch unit is composed of a matrix circuit in which
when a switch it touched, one of signals P43 - P45
generated by the LSI, is passed through the switch
and returned to the LSI as one of signals P50 - P51.

The encoder converts the signal generated by LSI into
the pulse signal, and the pulse signal is returned to the
LSI.