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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.

1. CARRY OUT 3D CHECKS.

2. Isolate the key unit with the control panel frame to be tested.

3. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the circuit between the pins of the key unit that

correspond to the STOP/CLEAR key. When the pad is pressed, the ohmmeter should indicate short circuit. When the pad is released, the ohmme-
ter should indicate open circuit. If incorrect readings are obtained, the key unit is faulty and must be replaced. About the other pads, the above
method may be used.

4. CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between the normal open terminal of the relay RY1 and the normal open 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.

RY1 and RY2 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.

CARRY OUT 4R CHECKS.

RELAY SYMBOL

OPERATIONAL VOLTAGE

CONNECTED COMPONENTS

RY1

Approx. 12.9V D.C.

Oven lamp / Turntable motor / Cooling fan motor

RY2

Approx. 12.3V D.C.

High voltage transformer

Pin 10

Pin 1

G1

G2

G3

G4

G5

G6

G7

G8

G9

G10

10 sec.

1 min.

10 min

AUTO

COOK

MEAT

JOINT

ROAST BEEF

LAMB

ROAST

PORK

ROAST

POULTRY

TIME

WEIGHT

STOP

CLEAR

START

AUTO MINUTE

WEIGHT

POWER

LEVEL

TIME

KITCHEN TIMER

CLOCK SET

CHICKEN

QUATERS

WHOLE

POULTRY

Key unit (Membrane Switch) front view

Key unit ribbon cable

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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.

NOTE: *At the time of making these repairs, make a visual inspection of the varistor.

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

CARRY OUT 4R CHECKS.

STEPS

OCCURRENCE

CAUSE OR CORRECTION

1

The rated AC voltage is not present between the normal open terminal of the 
relay RY1 and the normal open 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”.

(J1)

VRS1

RY1

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R269WM

Service Manual

 

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

(1) Key Unit      (2) Control Unit       

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

The key unit is composed of a matrix, signals generated in the LSI are
sent to the key unit through P22, P23, P24, P25, P26 and P33. When
a key pad is touched, a signal is completed through the key unit and
passed back to the LSI through P50, P51, P52 and P53 to perform the
function that was requested.

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 elec-
trodes 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.

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 (key touch sound and completion sound).

6) Synchronizing Signal Circuit

The power source synchronizing signal is available in order to com-
pose 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 han-
dling these parts, the following precautions should be strictly followed.
CMOS LSI have extremely high impedance at its input and output ter-
minals. For this reason, it is easily influenced 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.

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 exter-
nal power source.

1. Servicing the touch control panel with power supply of the oven:

CAUTION: THE HIGH VOLTAGE TRANSFORMER OF THE MICRO-

WAVE OVEN IS STILL LIVE DURING SERVICING 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.

3) Discharge high voltage capacitor.

4) Disconnect the leads to the primary of the power transformer.

5) Ensure that these leads remain isolated from other components

and oven chassis by using insulation tape.

6) After that procedure, re-connect the power supply cord.

After checking the performance of the touch control panel,

1) Disconnect the power supply cord.

2) Open the door and block it open.

3) Re-connect the leads to the primary of the power transformer.

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

5) Re-connect the power supply cord after the outer case is

installed.

6) Run the oven and check all functions.

a) On some models, the power supply cord between the touch

control panel and the oven itself is so short that the two can't
be separated. For those models, check and repair all the
controls (sensor-related ones included) of the touch control
panel while keeping it connected to the oven.

b) On some models, the power supply cord between the touch

control panel and the oven proper is so long enough that
they may be separated from each other. For those models,
therefore, it is possible to check and repair the controls of the
touch control panel while keeping it apart from the oven
proper; in this case you must short both ends of the door
sensing switch (on PWB) of the touch control panel with a
jumper, which brings about an operational state that is equiv-
alent to the oven door being closed. As for the sensor-
related controls of the touch control panel, checking them is
possible if the dummy resistor(s) with resistance equal to
that of the controls are used.

2. Servicing the touch control panel with power supply from an exter-

nal power source:

Symbol

Voltage

Application

VSS

-5V

LSI(IC1) 

approx. 1M ohm

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Disconnect the touch control panel completely from the oven
proper, and short both ends of the door sensing switch (on PWB) of
the touch control panel, which brings about an operational state
that is equivalent to the oven door being closed. Connect an exter-
nal power source to the power input terminal of the touch control
panel, then it is possible to check and repair the controls of the
touch control panel; it is also possible to check the sensor-related
controls of the touch control panel by using the dummy resistor(s).

Tools required to service the touch control panel assembly.

1) Soldering iron: 60W

(It is recommended to use a soldering iron with a grounding termi-
nal.)

2) Oscilloscope: Single beam, frequency range: DC - 10MHz type or

more advanced model.

3) Others: Hand tools

1) Before turning on the power source of the control unit, remove the

aluminium foil applied for preventing static electricity.

2) Connect the connector of the key unit to the control unit being sure

that the lead wires are not twisted.

3) After aluminium foil is removed, be careful that abnormal voltage

due to static electricity etc. is not applied to the input or output ter-
minals.

4) Attach connectors, electrolytic capacitors, etc. to PWB, making

sure that all connections are tight.

5) Be sure to use specified components where high precision is

required.