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R259(W)

9 – 3

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:

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.

63

BZO90

OUT

Signal to sound buzzer (2.0 kHz).
A: key touch sound.
B: Completion sound.

64

P20

OUT Terminal not used.

A

B

0.1 sec.

2.0 sec.

H : GND

L : -5V

H : GND

L : -5V

approx. 1M ohm

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10 – 1

R259(W)

Service Manual

 

The “Main PWB” of this model employs lead-free solder. This is indicated by the “LF” symbol printed on the PWB and in the service manual. The suffix
letter indicates the alloy type of the solder.

When repairing a PWB with the “LF” symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder may result in cold soldered
joints and damage to printed patterns.)

As the melting point of lead-free solder is approximately 40

°C higher than tin/lead alloy solder, it is recommend that a dedicated bit is used, and that

the iron temperature is adjusted accordingly.

As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wettability, (flow), to prevent damage to the land of the PWB, extreme
care should be taken not to leave the bit in contact with the PWB for an extended period of time. Remove the bit as soon as a good flow is achieved.
The high content of tin in lead free solder will cause premature corrosion of the bit. To reduce wear on the bit, reduce the temperature or turn off the
iron when it is not required. 

Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their characteristics, making good soldering
more difficult. It will be necessary to clean and replace bits more often when using lead-free solder. To reduce bit wear, care should be taken to clean
the bit thoroughly after each use.

Indicates lead-free solder of tin, silver and copper

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11 – 1

R259(W)

Service Manual

 

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in severe, possibly fatal,
electric shock.

(Example)

High Voltage Capacitor, High Voltage Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage fuse, High Voltage Harness etc..

WARNING:

1) Disconnect the power supply cord.

2) Visually check the door and cavity face plate for damage (dents,

cracks, signs of arcing etc.).

Carry out any remedial work that is necessary before operating the
oven.

Do not operate the oven if any of the following conditions exist;

1) Door does not close firmly.

2) Door hinge, support or latch hook is damaged.

3) The door gasket or seal is damaged.

4) The door is bent or warped.

5) There are defective parts in the door interlock system.

6) There are defective parts in the microwave generating and trans-

mission assembly.

7) There is visible damage to the oven.

Do not operate the oven:

1) Without the RF gasket (Magnetron).

2) If the wave guide or oven cavity are not intact.

3) If the door is not closed.

4) If the outer case (cabinet) is not fitted.

1. Before wiring, 

1) Disconnect the power supply cord.

2) Open the door and block it open.

3) Discharge the high voltage capacitor and wait for 60 seconds.

2. Don't let the wire leads touch to the following parts;

1) High voltage parts:

Magnetron, High voltage transformer, High voltage capacitor,
High voltage rectifier assembly and High voltage fuse.

2) Hot parts:

Oven lamp, Magnetron, High voltage transformer and Oven
cavity.

3) Sharp edge:

Bottom plate, Oven cavity, Waveguide flange and other metallic
plate.

4) Movable parts (to prevent a fault)

Fan blade, Fan motor, Turntable motor and Switch.

3. Do not catch the wire leads in the outer case cabinet.

4. Insert the positive lock connector certainly until its pin is locked and

make sure that the wire leads do not come off even if the wire leads
are pulled.

5. To prevent an error function, connect the wire leads correctly, refer-

ring to the Pictorial Diagram. 

Please refer to ‘OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS’, when carrying out any of the following removal proce-
dures:

To remove the outer case, procedure as follows.

1. Disconnect the oven from power supply.

2. Open the oven door and wedge it open.

3. Remove the two (2) screws from right side of the outer case cabi-

net.

4. Remove the five (5) screws from rear and along the side edge of

case.

5. Slide the entire case back about 3cm to free it from retaining clips

on the cavity face plate.

6. Lift the entire case from the oven.

7. Discharge the H.V. capacitor before carrying out any further work.

8. Do not operate the oven with the outer case removed.

NOTE: Step 1, 2 and 7 form the basis of the 3D checks.

CAUTION: DISCONNECT OVEN FROM POWER SUPPLY BEFORE

REMOVING OUTER CASE.

1. CARRY OUT 3D CHECKS.

2. Disconnect the wire leads (main wire harness and H.V. fuse) from

high voltage transformer.

 

                                                                                                

                                                      1) Disconnect the supply.                                                     3)Discharge high voltage capacitor.
                                                      2)Door opened, and wedged open.

R259(W)

11 – 2

3. Disconnect the filament lead of high voltage transformer from the

magnetron.

4. Disconnect the filament lead of the high voltage transformer from

high voltage capacitor.

5. Remove the two (2) screws holding the transformer to bottom plate

from below.

6. Remove the two (2) screws holding the transformer to bottom plate

from above. 

7. Remove the transformer. 

To remove the components, proceed as follows.

1. CARRY OUT 3D CHECKS.

2. Disconnect the H.V. fuse from the high voltage transformer.

3. Disconnect the H.V. wire of the H.V. rectifier assembly from the

magnetron.

4. Disconnect the filament lead of the high voltage transformer from

the H.V. capacitor.

5. Remove one (1) screw holding capacitor holder to the oven cavity

back plate.

6. Remove one (1) screw holding earth side terminal of high voltage

rectifier assembly, and remove capacitor holder.

7. Disconnect all the leads and terminals of high voltage rectifier

assembly from high voltage capacitor.

8. Disconnect the H.V. fuse from the high voltage capacitor.

9. Now H.V. rectifier assembly, H.V. fuse and H.V. capacitor should be

free.

CAUTION: WHEN REPLACING HIGH VOLTAGE RECTIFIER

ASSEMBLY, ENSURE THAT THE CATHODE (EARTH)
CONNECTION IS SECURELY FIXED TO THE CAPACI-
TOR HOLDER WITH AN EARTHING SCREW.

CAUTION: DO NOT REPLACE ONLY HIGH VOLTAGE RECTIFIER.

WHEN REPLACING IT, REPLACE HIGH VOLTAGE REC-
TIFIER ASSEMBLY.

1. CARRY OUT 3D CHECKS.

2. Disconnect the wire leads from the magnetron.

3. Remove the two (2) screws holding the air duct to the oven cavity.

4. Release the air duct from the oven cavity.

5. Carefully remove the four (4) screws holding the magnetron to the

waveguide flange.

6. Lift up magnetron with care so that the magnetron antenna is not

hit by any metal object around antenna.

7. Now, the magnetron is free.

1. Reinstall the magnetron to the waveguide flange with the four (4)

screws.

2. Reinstall the air duct to the oven cavity with the two (2) screws.

3. Reconnect the wire leads to the magnetron. Refer to “PICTORIAL

DIAGRAM”.

4. Reinstall the outer case and check that the oven is operating prop-

erly.

CAUTION: WHEN REPLACING THE MAGNETRON, BE SURE THE

R.F. GASKET IS IN PLACE AND THE MAGNETRON
MOUNTING SCREWS ARE TIGHTENED SECURELY.

1. CARRY OUT 3D CHECKS.

2. Push the lever of positive lock

® connector.

3. Pull down on the positive lock

® connector.

CAUTION: WHEN CONNECTING THE POSITIVE LOCK

®

CONNECTORS TO THE TERMINALS, CON-
NECT THE POSITIVE LOCK

® SO THAT THE

LEVER FACES YOU.

1. Disconnect the power supply cord.

2. Remove turntable and turntable support from oven cavity.

3. Lay the oven on it's backside. Remove the turntable motor cover by

snipping off the material in four corners.

4. Where the corners have been snipped off bend corner areas flat.

No sharp edges must be evident after removal of the turntable
motor cover.

5. Disconnect wire leads from turntable motor.

(See “Positive lock connector removal”)

6. Remove one (1) screw holding turntable motor to oven cavity.

7. Remove the TTM packing from the turntable motor.

Terminal

Push

Pull down

1

2

Lever

Positive lock¨

connector

Figure C-1. Positive lock, connector