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R-252M   17

approx. 1M ohm

This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following pre-
cautions should be strictly followed. CMOS LSI have
extremely high impedance at its input and output
terminals. For this reason, it is easily influenced by the
surrounding high voltage power source, static electric-
ity 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 con-
taining 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 external power source.

Therefore, when checking the performance of the
touch control panel, put the outer cabinet on the
oven to avoid touching the high voltage trans-
former, or unplug the primary terminal (connector)
of the high voltage transformer to turn it off; the end
of such connector must be insulated with an insulat-
ing tape. After servicing, be sure to replace the
leads to their original locations.

A. On some models, the power supply cord be-

tween 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 be-

tween 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 equivalent 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.

supply from an external 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 external power source to the power input termi-
nal 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 as-
sembly.
1) Soldering iron: 30W

(It is recommended to use a soldering iron with a
grounding terminal.)

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 prevent-
ing 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 terminals.

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.

R-252M   18

1. Disconnect oven from power supply.
2. Visually check the door and cavity face plate for dam-

age (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 or 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 transmission 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.

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

6. Discharge the H.V. capacitor before carrying out any

further work.

7. Do not operate the oven with the outer case removed.
NOTE; Step 1, 2 and 6 form the basis of the 3D checks.

CAUTION: DISCHARGE HIGH VOLTAGE CAPACI-

TOR BEFORE TOUCHING ANY OVEN
COMPONENT OR WIRING.

To remove the outer case proceed as follows.
1. Disconnect oven from power supply.
2. Open the oven door and wedge it open.
3. Remove the screws from rear and along the side edge

of case.

4. Slide the entire case back about 3 cm to free it from

retaining clips on the cavity face plate.

5. Lift the entire case from the oven.

7. Now, the high voltage rectifier and the capacitor should

be free.

CAUTION: WHEN REPLACING HIGH VOLTAGE REC-

TIFIER, ENSURE THAT THE CATHODE
(EARTH) CONNECTION IS SECURELY
FIXED TO THE CAPACITOR HOLDER AND
BASE PLATE WITH AN EARTHING
SCREW.

To remove the components, proceed as follows.
1. CARRY OUT 3D CHECKS.
2. Disconnect all the leads and the terminal of high

voltage rectifier from the high voltage capacitor.

3. Remove one (1) screw holding earth side terminal of

the high voltage rectifier and remove the capacitor
holder from the base plate.

4. Remove the capacitor from the capacitor holder.

Ensure the following:

1. Wires must not touch:

a) High voltage parts.
    (Magnetron, high voltage transformer, high voltage capacitor and high voltage rectifier assembly)
b) Parts that become hot.
    (Heating elements, oven lamp, oven cavity magnetron and high voltage transformer)
c) Sharp edges.
    (Bottom plates, oven cavity, waveguide flange, chassis support and other metallic parts)
d) Movable parts.
    (Fan blade, any motor, switch, switch lever and open button)

2. Positive lock connectors are fitted correctly.
3. Wires are connected correctly as per pictoral diagram.
4. No wire leads are trapped by the outer wrap.

WARNING: WIRING/RE-WIRING
Before carrying out any work; carry out 3D checks.
1. Disconnect the supply.
2. Door opened, and wedged open.
3. Discharge the high voltage capacitor.

R-252M   19

1. CARRY OUT 3D CHECKS.
2. Disconnect the wire leads from the fan motor.
3. Remove the two (2) screws holding the fan motor to the

oven cavity back plate.

4. Remove the fan blade from the fan motor shaft accord-

ing to the following procedure.
1) Hold the edge of the rotor of the fan motor by using

a pair of groove joint pliers.

2) Remove the fan blade from the shaft of the fan

motor by pulling and rotating the fan blade with your
hand.

3) Now, the fan blade will be free.

5. Now, the fan motor is free.

1.

Install the fan blade to the fan motor shaft according
to the following procedure.

1)

Hold the centre of the bracket which supports the
shaft of the fan motor on a flat table.

2)

Install the fan blade to the shaft of fan motor by
pushing the fan blade with a small, light weight, ball
peen hammer or rubber mallet.

2.

Install the fan motor to the oven cavity back plate with
the two (2) screws.

1. Disconnect the oven from the power supply.
2. Remove the turntable motor cover by snipping off the

material in four corners.

3. Where the corners have been snipped off bent corner

areas flat. No sharp edge must be evident after re-
moval of turntable motor cover.

4. Disconnect the wire leads from the turntable motor and

remove the one (1) screw holding the turntable motor.

5. Turntable motor is now free.
6. After replacement use the one (1) screw to fit the

turntable motor cover.

1. CARRY OUT 3D CHECKS.
2. Disconnect the main wire harness and the stop switch

harness from the control panel.

3. Remove the one (1) screw holding the control panel to

the oven cavity.

4. Lift the control panel assembly and pull it forward.

Now, the control panel assembly is free.

1. CARRY OUT 3D CHECKS.
2. Disconnect the H.V. wire B and filament lead of the

transformer from the magnetron.

3. Remove the chassis support screw and the screw

holding chassis support to magnetron.

4. Move the air intake duct to left.
5. Carefully remove two (2) screws holding magnetron to

the waveguide, when removing the screws hold the
magnetron to prevent it from falling.

6. Remove the magnetron from the waveguide with care

so the magnetron antenna is not hit by any metal object
around the antenna.

CAUTION: WHEN REPLACING THE MAGNETRON,

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

REINSTALL THE MAGNETRON TO WAVE
GUIDE FLANGE WITH THE TWO (2)
SCREWS DIAGONALLY.

1. CARRY OUT 3D CHECKS.
2. Disconnect the filament leads of high voltage trans-

former from high voltage capacitor and the magnetron.

3. Disconnect the H.V. wire A from the high voltage

transformer.

4. Remove the four (4) screws holding the transformer to

base plate.

7. Remove the transformer.
8. Now the high voltage transformer is free.

R-252M   20

1. CARRY OUT 3D CHECKS.
2. Remove the one (1) screw and nut holding the green/

yellow wire to the oven cavity.

3. Disconnect the leads of the power supply cord from the

noise filter, referring to the Figure C-1(a).

4. Release the power supply cord from the rear cabinet.
5. Now, the power supply cord is free.

1. Insert the moulding cord stopper of power supply cord

into the square hole of the rear cabinet, referring to the
Figure C-1(b). Installation of Power supply cord.

2. Install the earth wire lead of power supply cord to the

oven cavity with one (1) screw and nut, tighten the
screw.

3. Connect the brown and blue wire leads of power supply

cord to the noise filter correctly, referring to the Pictorial
Diagram.

OVEN CAVITY
BACK PLATE

SQUARE HOLE

MOULDING
CORD
STOPPER

POWER SUPPLY
CORD

GROMMET
MOULDING

1. CARRY OUT 3D CHECKS.
2. Disconnect the wire lead from the oven lamp, refer-

ring to "Positive lock

®

 connector removal".

3. Lift up the oven lamp with release.
4. Now, the oven lamp is free.

BULB

LOCK

3. Reconnect the wire leads to the fan motor, referring to

the pictorial diagram.

1. CARRY OUT 3D CHECKS.
2. Push the lever of positive lock

®

 connector.

3. Pull down on the positive lock

®

 connector.

CAUTION: WHEN YOU (SERVICE ENGINEERS) CON-

NECT THE POSITIVE LOCK

®

 CONNEC-

TORS TO THE TERMINALS, CONNECT
THE POSITIVE LOCK

®

 SO THAT THE LE-

VER FACES YOU .

Terminal

Push

Pull down

1

2

Lever

Positive lock®

connector

Coil

Gap

Rotor

Bracket

Stator

Groove joint pliers

Shaft

Axis

Stator

Rotor

These are the position 
where should be 
pinched with pliers

Shaft

Table

Center of 
bracket

OVEN CAVITY
BACK PLATE

BROWN WIRE

POWER 
SUPPLY CORD

CHASSIS SUPPORT

BLUE WIRE

NOISE FILTER

N

L

F1

RED

WHT