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Transistor
KIA79L05P
DTB143ES
DTD143ES
KRA101M

Transistor
2SB1238

Transistor
2SB953

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 all 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 external power source.

(1) Servicing the touch control panel with power supply of

the oven:
CAUTION: THE HIGH VOLTAGE TRANSFORMER

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 itself is so short that
the two can’t be separated. For those models, check
and repair all the controls (sensor-related ones in-
cluded) 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 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 dummy
resistor(s) with resistance equal to that of the controls
are used.

(2) Servicing the touch control panel with power 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 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 as-
sembly.

1) Soldering iron: 60W

(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

5. Other Precautions
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 abnor-

mal 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.

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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.
Example:

Indicates lead-free solder of tin, silver and copper.

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.

Sn-Ag-Cu

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1. Disconnect the oven from power supply.
2. Make sure that a definite “click” can be heard when the

microwave oven door is unlatched. (Hold the door in a
closed position with one hand, then grip the door
handle and the door lever assembly with the other, this
causes the latch leads 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 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 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.

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

T

o remove the components, procedure as follows.

1. Disconnect oven from power supply.
2. Open the oven door and wedge it open.
3. Remove the screws from the rear and along side the edge of

the outer case.

4. Slide the case back about 1 inch (3 cm) to free it from the oven

cavity.

5. Lift entire case from the unit.
6. DISCHARGE TWO HIGH VOLTAGE CAPACITORS BE-

7. Now, outer case is free.
N.B.; Step 1,2 and 9 form the basis of the 3D checks.

CAUTION: DISCHARGE TWO HIGH VOLTAGE CAPACI-

TORS BEFORE TOUCHING ANY OVEN COM-
PONENTS OR WIRING.

To remove rear cabinet and power supply cord:
8. Disconnect the power supply cord from the noise filter.
9. Remove the one (1) screws holding the grounding wire of

power supply cord to the oven cavity.

10. Remove the screws holding the rear cabinet to the oven

cavity and blower motor.

11. Remove the  rear cabinet with the power supply cord from the

oven cavity.

12. Loosen the tab of the cord bushing, and remove the power

supply cord with the cord bushing from the rear cabinet.

13. Remove the cord bushing from the power supply cord,
14. Now, the power supply cord and rear cabinet are free.

To prevent an electric shock, take the following
precautions.
1. Before wiring,

1) Disconnect the power supply cord.
2) Open the door and block it open.
3) Discharge the two high voltage capacitors and

wait for 60 seconds.

2. Don’t let the wire leads touch to the followiong parts;

1) High voltage parts:

Magnetron, High voltage transformer, High volt-
age 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,
Chassis support and other metallic plate.

4) Movable parts (to prevent a fault)

Blower fan blade, Blower fan motor, Switches,
Switch levers, Antenna motors and Sirrer anten-
nas.

3. Do not catch the wire leads in the outer case cabinet.
4. Insert the positive lock connector 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, referring to the Pictorial Diagram.

1. CARRY OUT 3D CHECKS.
2. Remove the rear cabinet, too.
3. Disconnect wire lead(s) of high voltage transformer(s) from

magnetron(s).

4. Remove the wire lead(s) of high voltage transformer(s) from

the wire holder.

5. Pull out the wire lead(s) of high voltage transformer(s) from

the tube.

6. Disconnect wire lead(s) of high voltage transformer(s) from

high voltage capacitor(s).

7. Disconnect the high voltage fuse(s) from high voltage

transformer(s).

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8. Disconnect the main wire harness from high voltage

transformer(s).

9. Remove two (2) screws holding each power transformer to

1. CARRY OUT 3D CHECKS.
2. Remove the rear cabinet, too.
3. Remove the magnetron from the waveguide flange, referring

to "MAGNETRON(S)  REMOVAL".

4. Now, the magnetron with the magnetron thermistor should

be free.

5. Remove the thermistor angle from the magnetron by pulling

out.

6. Straighten the tab of the magnetron thermistor angle holding

the magnetron thermistor.

7. Remove the magnetron thermistor from the thermistor angle.
8. Now, the magnetron thermistor is free.

Re-install
1. Install the magnetron thermistor to the thermistor angle as

shown in Figure C-1.

2. Hold the magnetron thermistor to the thermistor angle by

bending the tab of the thermistor angle.

3. Insert the thermistor angle between the 2nd. fin and 3rd. fin

from the upper fin of the magnetron and push it until the
thermistor angle stops.

NOTE: The magnetron thermistor should be between the upper

fin and the 2nd. fin.

4. Re-install the magnetron to the waveguide flange with four

(4) screws.

base plate.

10. Remove the high voltage transformer(s) from base plate.
12. Now, high voltage transformer(s) are free.

Removal
1. CARRY OUT 3D CHECKS.
2. Remove the rear cabinet, too.
3. Remove the two (2) screws holding magnetron exhaust duct

to upper and lower waveguide.

4. Remove the magnetron exhaust duct from oven cavity.
5. Disconnect wire leads from magnetron(s ).
6. Disconnect  magnetron thermistor from the connector of the

stop switch harness.

7. Remove the one (1) screw holding the thermistor angle to the

upper magnetron.

8. Remove the four (4) screws holding each magnetron to upper

and/or lower waveguide. When removing the screws, hold
the magnetron   to prevent it from falling.

9. Remove the magnetron(s) from upper and/or lower waveguide

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

10. Pull out the thermistor angle from the upper magnetron.
11. Now, the magnetron(s) is (are) free.

CAUTION: WHEN REPLACING MAGNETRON, BE SURE

THE R.F. GASKET IS IN PLACE AND MOUNT-
ING SCREWS ARE TIGHTENED SECURELY.

5. Re-install the thermistor angle to the waveguide flange with

one (1) screw.

6. Re-install the magnetron exhaust duct to the upper and lower

waveguide flanges with two (2) screws.

7. Route the thermistor harness under the magnetron tempera-

ture fuse.

8. Connect the thermistor harness to the stop switch harness.
9. Connect the wire leads to the upper magnetron, referring to

the pictorial diagram.

10. Re-install the power supply cord, rear cabinet and outer case

cabinet to the oven by reversing the procedures of  "OUTER
CASE, REAR CABINET AND POWER SUPPLY CORD
REMOVAL".

1. CARRY OUT 3D CHECKS.
2. Remove the rear cabinet, too.
3. Remove  two (2) screws holding earth side terminals of high

voltage rectifier assembly to the capacitor holder and oven
cavity.

4. Disconnect all wire leads from the high voltage capacitor.
5. Disconnect high voltage fuse(s) from the high voltage

transformer(s). Now, high voltage fuse(s) is(are) free.

6. Remove the three (3) screws holding the blower motor to the

top of oven cavity, the chassis support and air duct.

7. Disconnect high voltage wire lead(s) of the high voltage

rectifier assembly from the magnetron(s).
Now, the the high voltage rectifier assembly is free.

8. Remove  two (2) screws holding the capacitor holder to oven

cavity.
Now, the capacitors are free.

CAUTION:
1. DISCHARGE THE TWO HIGH VOLTAGE CAPACITORS

BEFORE TOUCHING ANY OVEN COMPONENTS OR WIR-
ING.

2. DO NOT REPLACE ONLY THE HIGH VOLTAGE RECTI-

FIER. IF IT IS DEFECTIVE, REPLACE THE HIGH VOLT-
AGE RECTIFIER ASSEMBLY.

3. WHEN REPLACING THE HIGH VOLTAGE RECTIFIER

ASSEMBLY AND THE HIGH VOLTAGE CAPACITOR, THE
CATHODE (EARTH) SIDE TERMINAL OF THE HIGH VOLT-
AGE RECTIFIER MUST BE SECURED FIRMLY WITH A
EARTHING SCREW.

Upper magnetron

Upper fin

Tab

Thermistor
angle

Magnetron 
thermistor

1. CARRY OUT 3D CHECKS.
2. Remove the rear cabinet, too.
3. Disconnect the wire leads from the blower motor and noise

filter.

4. Remove the one (1) screw holding the blower motor angle to

the oven cavity.

5. Remove the one (1) screw holding the blower motor angle to

the chassis support.