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871M - 13

 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 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.

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

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.

Transistor
2SB1238

Transistor
DTA123ES
KRA101M
KRC243M

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 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 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.

 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.

871M - 14

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.

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.

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.

1. CARRY OUT 3D CHECKS.
2. Remove the control panel assembly referring to

"CONTROL PANEL REMOVAL".

3. Disconnect the leads from all switches.
4. Remove the two (2) screws holding the latch hook to the

oven cavity.

5. Remove the latch hook.
6. Push the retaining tab slightly and remove the switch.

1. CARRY OUT 3D CHECKS.
2. Remove the fan duct from the oven cavity, referring to

"FAN MOTOR REPLACEMENT".

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.

5. Release the grill heating element assembly from the

oven cavity by sliding the cover.

6. Now the grill heating element assembly is free.

MONITOR SWITCH

1ST LATCH SWITCH

TAB

TAB

STOP SWITCH

MONITORED LATCH SWITCH

871M - 15

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.

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

871M - 16

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

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 downwards 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 o 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.

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. Door is positioned with its face pressed toward cavity

face plate.

4. 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