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10

891M -

Components
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 all PW boards

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.

supply of the oven:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE
MICROWAVE OVEN IS STILL LIVE DURING
SERVICING PRESENTS A HAZARD.
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.

Transistor
2SB1238

Transistor
KRC243M

containing them in aluminium foil.

2) When soldering, ground the technician as shown in

approx. 1M ohm

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
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.

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
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

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 connectors 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.

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891M -

1. Disconnect oven from power supply and remove outer case.

2. Discharge high voltage capacitor.

3. Remove the control panel assembly from the oven, referring to "CONTROL PANEL ASSEMBLY REMOVAL".

4. Remove the five (5) screws holding the display unit and the power unit to the control panel frame.

5. Remove the display unit and the power unit from the control panel frame.

6. Remove the solder holding the tab (near capacitor C11) of LCD vessel to the printed wiring board.

7. Make the four (4) tabs of LCD vessel straight.

8. Release the LCD vessel from the printed wiring board.

9. Now, the two (2) lamps LMP1 and LMP2 can be found.

10. Remove the solder holding the lamps LMP1 and LMP2 to the printed wiring board.

11. Now, the lamps LMP1 and LMP2 are free.

LCD
vessel
tab

IC2

IC1

C11

LCD
vessel
tab

NOTE:  The CPU/Display unit is not suitable for service repair for individual components.  However by referring to this page

the back light lamp can only be repaired.

12

891M -

7. Remove the one (1) nut holding the convection fan,

washers, pipe and auxiliary fan to the convection fan
motor shaft.

8. Remove the two (2) screws holding the convection motor

mounting plate to the convection fan duct.

9. Remove the pin on the convection fan motor shaft.
10. Remove the two (2) screws holding the convection motor

mounting plate to the convection fan motor.

11. Now, the convection fan motor is free.

CONVECTION FAN MOTOR
1. CARRY OUT3DCHECKS.
2. Remove the two (2) screws holding the back plate to oven

cavity.

3. Disconnect the wire leads from the convection motor.
4. Remove the two (2) screws holding the convection fan

duct to the oven cavity from out-side.

5. Remove the four (4) screws holding the convection fan

duct to the oven cavity.

6. Now the convection fan duct is free.

pulling lower portion of door toward the oven face. Both
results (plays of the door) should be less than 0.5mm.

2. The 1st latch switch and stop switch interrupt the circuit

before the door can be opened.

3. The monitor switch contacts of (COM.- NC.) close when

the door is opened and the monitored latch switch contacts
of (COM.- NO.) open and  contacts of (COM.- NC.) close
when the door is opened.

4. Re-install outer case and check for microwave leakage

around the door with an approved microwave survey
meter. (Refer to Microwave Measurement Procedure.)

If the monitored switch, stop switch and monitor switch do not
operate properly due to a mis-adjustment, the following
adjustment should be made.
1. CARRY OUT 3D CHECKS
2. Loosen the two (2) screw holding the latch hook to the

oven cavity front flange.

3. With the door closed, adjust latch hook by moving it back

and forward or up and down. In and out play of the door
allowed by the latch hook should be less than 0.5 mm.
The horizontal position of the latch hook should be placed
where the latch head has pushed the plungers of the
monitor switch with the door closed. The vertical position
of the latch hook should be placed where the latch head
has pushed the plungers of the monitored latch switch
and stop switch with the door closed.

4. Secure the screws firmly.
5. Make sure all of the switches operate. If the latch head

has not pushed the plungers of the monitor switch with
door closed, adjust the latch hook position.
At that time, the latch head should have pushed the
plungers of the monitored latch switch and stop switch. If
the latch head has not pushed the plungers of the
monitored latch switch and stop switch with door closed,
loose two (2) screws holding latch hook to oven cavity
front flange and adjust the latch hook position.

After adjustment, make sure of the following:
1. In and out play of door remains less than 0.5 mm when

latched position. First check latch hook position, pushing
and pulling upper portion of door toward the oven face.
Then check the lower latch hook position, pushing and

LATCH
HEADS

LATCH HOOK

MONITORED LATCH
SWITCH

STOP SWITCH

OPEN LEVER

DOOR OPEN BUTTON

MONITOR 
SWITCH

GRILL HEATER
1. CARRY OUT 3D CHECKS
2. Disconnect the wire leads to the grill heating element.
3. Remove the two(2) screws holding the exhaust duct

assembly to the oven cavity.

4. Push the two tabs holding the grill heating element

assembly to the oven cavity.

5. Release the grill heating element assembly from the

oven cavity by sliding the cover.

6. Now the grill heating element assembly is free.

BOTTOM HEATER
1. CARRY OUT 3D CHECKS.
2. Remove the fan duct from the oven cavity.
3. Disconnect the wire leads from the bottom heating

element.

4. Remove the two (2) nuts holding the bottom heating

element to the oven cavity right wall.

5. Remove the two (2) nuts holding the bottom heating

element to the heater cover with the heat sealed spring
at the oven cavity left wall.

6. Remove the bottom heating element from the oven

cavity.

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891M -

CHOKE COVER

PUTTY KNIFE

DOOR FRAME

1. CARRY OUT 3D CHECKS.
2. Push the open button and open the door slightly.
3. Insert a putty knife (thickness of about 0.5mm) into the

gap between the choke cover and door frame as shown
in Figure C-5 to free engaging parts.

4. Release choke cover  from door panel.
5. Now choke cover is free.
6. Lift the door upwards.
7. Now, door sub assembly is free from oven cavity.
8. Remove the four (4) screws holding the door panel to the

door frame.

9. Release door panel from six (6) tabs of door frame by

sliding door panel downward.

10. Now, door panel is free.
11. Slide latch head upward and remove it from door frame

with releasing latch spring from door frame and latch
head.

12. Now, latch head and latch spring are free.
13. Remove the two (2) screws holding the glass stopper to

the door frame.

14. Remove the glass stopper from the door frame.
15. Slide the front door glass leftwards and then slide

downwards to release the tabs holding it.

16. Now, the front door glass is free

RE-INSTALL
1. Re-install the front door glass to the door frame as follows.

Insert the upper edge of the front door glass into the six
(6) tabs of the door frame.

a) Slide the front door glass upwards and insert the lower

edge of the front door glass into the six (6) tabs of the door
frame.

b) Slide the front door glass rightwards and insert the right

edge of the front door glass into the one (1) tab of the door
frame.

2. Re-install the glass stopper and the door frame as follows.

Re-install the glass stopper to the door frame so that the
two (2) holes of the glass stopper meet the two (2) pins of
the door frame.

a) Hold the glass stopper to the door frame with the two (2)

screws.

3. Re-install the latch spring to the latch head. Re-install the

latch spring to the door frame. Re-install latch head to
door frame.

4. Re-install door panel to door frame by fitting six (6) tabs

of door frame to six (6) holes of door panel.

5. Hold the door panel to the door frame with four (4) screws.
6. Locate door panel hinge pins into cavity hinge location

holes.

7. Re-install choke cover  to door panel by clipping into

position.

After any service, make sure of the following :
1. Door latch heads smoothly catch latch hook through latch

holes and that latch head goes through centre of latch
hole.

2. Deviation of door alignment from horizontal line of cavity

face plate is to be less than 1.0mm.

3. Check for microwave leakage around door with an

approved microwave survey meter.  (Refer to Microwave
Measurement Procedure.)

Note:

The door on a microwave oven is designed to act as
an electronic seal preventing the leakage of
microwave energy from oven cavity during cook
cycle. This function does not require that door be air-
tight, moisture (condensation)-tight or light-tight.
Therefore, occasional appearance of moisture, light
or sensing of gentle warm air movement around
oven door is not abnormal and do not of themselves,
indicate a leakage of microwave energy from oven
cavity.

PIN

PIN

OVEN HINGE

CHOKE COVER

DOOR
PANEL

DOOR SUB 
ASSEMBLY