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R-24STM - 13

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 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.

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 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 transformer, 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 insulating tape.
After servicing, be sure to replace the leads to their
original locations.

A. On some models, the power supply cord between

the touch control panel and the oven 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

Transistor
2SA1267Y
KRA101M
KRC101M
KRC105M

panel while keeping it  connected to the oven.

B. On some models, the power supply cord between

the touch control panel and the oven 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; 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, 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 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: 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 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 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-24STM - 14

1. CARRY OUT 3D CHECKS.
2. Make sure that a definite "click" can be heard when the

microwave oven door is unlatched. (Hold the door in a
closed position, then pull the door open slowly, this
causes the latch heads to rise, it is then possible to hear
a "click" as the door switches operate.)

3. 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 hinges or latch hook is damaged.
3. The door 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 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.

To remove the components, proceed as follows.

1. CARRY OUT 3D CHECKS
2. Disconnect all the leads and terminal of high voltage

rectifier from high voltage capacitor.

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

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

4. Remove the capacitor from the capacitor holder.
5. Now the high voltage rectifier and capacitor should be

free.

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

To remove the outer case, proceed as follows.
1. Disconnect oven from power supply.
2. Remove the screws from rear and along the side edge

of case.

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

retaining clips on the cavity face plate.

4. Lift the entire case from the oven.

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

further work.

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

CAUTION: DISCHARGE HIGH VOLTAGE

CAPACITOR BEFORE TOUCHING ANY
OVEN COMPONENTS OR WIRING.

CAUTION: WHEN REPLACING HIGH VOLTAGE

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

R-24STM - 15

REMOVAL
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.  The fan motor is now free.

4. Remove the fan blade from the fan motor shaft according

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.
INSTALLATION
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 removal
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 repplacement use the one (1) screw to fit the

turntable motor cover.

1. CARRY OUT 3D CHECKS.
2. Disconnect the main wire 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 transformer

from high voltage capacitor and the magnetron.

3. Disconnect the H.V. wires from the high voltage capacitor

and magnetron.

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-24STM - 16

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

1. CARRY OUT 3D CHECKS.

2. Disconnect the wire lead from the oven lamp, referring

to "Positive lock

®

 connector removal".

3. Lift up the oven lamp from the clips of the air intake duct.
4. Now, the oven lamp is free.

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.
Re-install
1. Insert the moulding cord stopper of power supply cord

into the square hole of the rear cabinet, referring to the

Power supply cord

Oven cavity 
back plate

Green / Yellow
Wire

Brown Wire

Noise filter

Chassis
support

Blue Wire

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 and tighten.

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

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

3. Re-connect the wire leads to the fan motor, referring to the

pictorial diagram.

CAUTION: WHEN YOU (SERVICE ENGNEERS) CON-

NECT THE POSITIVE LOCK

®

 CONNEC-

TORS TO THE TERMINALS, CONNECT THE
POSITIVE LOCK

®

 SO THAT THE LEVER

FACES YOU.

Terminal

Push

Pull down

1

2

Lever

Positive lock®

connector

3. Pull down on the positive lock

®

 connector.

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

®

 connector.

Lock

Socket

Bulb

OVEN CAVITY
BACK PLATE

SQUARE HOLE

MOULDING
CORD
STOPPER

POWER SUPPLY
CORD

GROMMET
MOULDING