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R-795M- 

21

47

P21

OUT

Grill (TOP) heating element driving signal.
To turn on and off the grill heating element relay
(RY3). “L” level during grill cooking, oven cooking or
dual cooking. “H” level otherwise. The heater relay
turns on and off within a 54 second time base in
accordance with the special progrom in LSI.

48

P20

OUT

Oven lamp and turntable motor driving signal(Square Waveform : 50Hz).
To turn on and off shut-off relay (RY1).
The square waveform voltage is
delivered to the relay (RY1) driving
circuit.

49-50

P17-P16

OUT

Terminal not used.

51-80

SEG39-SEG10

OUT

Segment data signal.
Connected to LCD.
The relation between signals are as follows:

LSI signal (Pin No.)

LCD (Pin No.)

LSI signal (Pin No.) LCD (Pin No.)

SEG 0 (90) .................... SEG39 (51)

SEG21 (69) ................. SEG19 (19)

SEG 1 (89) .................... SEG38 (50)

SEG22 (68) ................. SEG18 (18)

SEG 2 (88) .................... SEG37 (49)

SEG23 (67) ................. SEG17 (17)

SEG 3 (87) .................... SEG36 (48)

SEG24 (66) ................. SEG16 (16)

SEG 4 (86) .................... SEG35 (47)

SEG25 (65) ................. SEG15 (15)

SEG 5 (85) .................... SEG34 (46)

SEG26 (64) ................. SEG14 (14)

SEG 6 (84) .................... SEG33 (45)

SEG27 (63) ................. SEG13 (13)

SEG 7 (83) .................... SEG32 (44)

SEG28 (62) ................. SEG12 (12)

SEG 8 (82) .................... SEG31 (43)

SEG29 (61) ................. SEG11 (11)

SEG10 (80) ................... SEG30 (30)

SEG30 (60) ................. SEG10 (10)

SEG11 (79) ................... SEG29 (29)

SEG31 (59) ................... SEG 9 ( 9)

SEG12 (78) ................... SEG28 (28)

SEG32 (58) ................... SEG 8 ( 8)

SEG13 (77) ................... SEG27 (27)

SEG33 (57) ................... SEG 7 ( 7)

SEG14 (76) ................... SEG26 (26)

SEG34 (56) ................... SEG 6 ( 6)

SEG15 (75) ................... SEG25 (25)

SEG35 (55) ................... SEG 5 ( 5)

SEG16 (74) ................... SEG24 (24)

SEG36 (54) ................... SEG 4 ( 4)

SEG17 (73) ................... SEG23 (23)

SEG37 (53) ................... SEG 3 ( 3)

SEG18 (72) ................... SEG22 (22)

SEG38 (52) ................... SEG 2 ( 2)

SEG19 (71) ................... SEG21 (21)

SEG39 (51) ................... SEG 1 ( 1)

SEG20 (70) ................... SEG20 (20)

81

SEG9

OUT

Terminal not used.

82-90

SEG8-SEG0

OUT

Segment data signal.
Connected to LCD. Signal is similar to SEG39.

91

VCC

IN

Connected to GND.

92

VREF

IN

Connected to GND.

93

AVSS

IN

Connected to VC.

94

COM3

OUT

Terminal not used.

95

COM2

OUT

Common data signal: COM3.
Connected to LCD (Pin No. 35).

96

COM1

OUT

Common data signal: COM2.
Connected to LCD (Pin No. 34).

97

COM0

OUT

Common data signal: COM1.
Connected to LCD (Pin No. 33).

98-99

VL3-VL2

IN

Power source voltage input terminal.
Standard voltage for LCD.

100

C2

IN

Terminal not used.

The I/O signal of the LSI are detailed in the following table

During cooking

L

H

20 msec.

ON

OFF

During

cooking

L

GND

H.

(Grill, Oven, Dual )

R-795M

22

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.

We describe the procedures to permit servicing of the
touch control panel of the microwave oven and the pre-
cautions 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.

T

herefore, before checking the performance of the touch

control panel,
1) Disconnect the power supply cord, and then remove

outer case.

2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power

transformer.

5) Ensure that these leads remain isolated from other

components and oven chassis by using insulation
tape.

6) After that procedure, re-connect the power supply

cord.

After checking the performance of the touch control

panel,

1) Disconnect the power supply cord.
2) Open the door and block it open.
3) Re-connect the leads to the primary of the power

transformer.

4) Re-install the outer case (cabinet).
5) Re-connect the power supply cord after the outer

case is installed.

6) Run the oven and check all functions.

 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.

 On some models, the power supply cord between the

touch control panel and the oven 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 the
dummy resistor(s) with resistance equal to that of the
controls are used.

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 assem-
bly.
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 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.

approx. 1M ohm

Transistor
KRC243M
KTA1274

R-795M- 

23

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.

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 one (1) screw holding the back plate to the

oven cavity rear plate. Remove the back plate

4. Remove the one (1) screw holding the air duct assem-

bly to the oven cavity rear plate.

5. Remove the air duct assembly
6. Remove the eight (8) screws from rear and along the

side edge of case.

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

retaining clips on the cavity face plate.

8. Lift the entire case from the oven.

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

further work.

10.Do not operate the oven with the outer case removed.
N.B.; Step 1, 2 and 9 form the basis of the 3D checks.

CAUTION: DISCHARGE HIGH VOLTAGE CAPACI-

TOR BEFORE TOUCHING ANY OVEN
COMPONENT OR WIRING.

CAUTION: WHEN THE OUTER CASE CABINET IS

RE-INSTALLED, INSTALL IT BEFORE THE
BACK PLATE IS INSTALLED, OR THE
OUTER CASE CABINET WILL BE DE-
FORMED.

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

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

1) Disconnect the power supply.
2) Open the door and wedge the door open.
3) Discharge the high voltage capacitor and wait for

60 seconds.

2. Don't let the wire leads touch to the following parts;

1) High voltage parts:

Magnetron, High voltage transformer, High volt-
age capacitor and High voltage rectifier assem-
bly.

2) Hot parts:

Top heating element, Bottom heating element,

Oven lamp, Magnetron, High voltage transformer
and Oven cavity.

3) Sharp edge:

Bottom plate, Oven cavity, Weveguide flange,
Chassis support and other metallic plate.

4) Movable parts (to prevent a fault)

Fan blade, Fan motor, Switch, Turntable motor.

3. Do not catch the wire leads in the outer case cabinet.
4. Insert the positive lock connector certainly until its pin

is locked. And make sure that the wire leads should
not  come off even if the wire leads is pulled.

5. To prevent an error function, connect the wire leads

correctly, referring to the Pictorial Diagram.

To remove the components, proceed as follows.
1. CARRY OUT 3D CHECKS.
2. Disconnect the filament lead of the high voltage trans-

former and the high voltage transformer secondary
wire  from the high voltage capacitor.

3. Disconnect the high voltage wire B from the magnetron.
4. Remove one (1) screw holding earth side terminal of

the high voltage rectifier assembly.

5. Remove one (1) screw holding fan duct to the oven

cavity rear plate.

6. Remove one (1) screw holding capacitor holder to the

oven cavity rear plate.

7. Release the capacitor holder from the fan duct.
8. Remove the high voltage capacitor from the capacitor

holder.

9. Disconnect the high voltage wire B and the high voltage

rectifier assembly from the high voltage capacitor.

10.Disconnect the high voltage rectifier assembly from the

high voltage wire B.

11.Now, the high voltage rectifier assembly and the high

voltage capacitor should be free.

CAUTION: WHEN REPLACING HIGH VOLTAGE

RECTIFIER ASSEMBLY, ENSURE THAT
THE CATHODE (EARTH) CONNECTION
IS SECURELY FIXED TO THE CAPACI-
TOR HOLDER WITH AN EARTHING
SCREW.

R-795M

24

1. CARRY OUT 3D CHECKS.
2. Disconnect the wire leads and the connectors from the

control unit.

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

assembly to the oven cavty front plate.

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

Now the control panel assembly is free.

NOTE:
1. Before attaching a new key unit, wipe off remaining

adhesive on the control panel frame surfaces com-
pletely with a soft cloth soaked in alcohol.

2. When attaching the key unit to the control panel frame,

adjust the upper edge and right edge of the key unit to
the correct position of  control panel frame.

3. Stick the key unit firmly to the control panel frame by

rubbing with soft cloth not to scratch.

12.Remove the two (2) screws and nuts holding the fan

motor to the fan duct.

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 high voltage transformer secondary

wire  from the high voltage transformer.

4. Disconnect the main wire harness from the high volt-

age transformer.

5. Remove the two (2) screws and one (1) washer holding

the transformer to the base plate.

7. Remove the transformer.
8. Now the high voltage transformer 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 one (1) screw holding the chassis support

to the magnetron.

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

Terminal

Push

Pull down

1

2

Lever

Positive lock¤
connector

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 .

1. CARRY OUT 3D CHECKS.
2. Remove the one (1) screw holding the noise filter to the

chassis support.

3. Release the noise filter from the tabs of the fan duct.
4. Remove the one (1) screw holding the chassis support

to the oven cavity front flange.

5. Remove one(1) screw holding the chassis support to the

magnetron.

6. Remove the chassis support from the oven cavity.
7. Disconnect the wire leads from the fan duct.
8. Remove the one (1) screw holding the capacitor holder

to the oven cavity back plate.

9. Release the tabs of the capacitor holder from the fan

duct.

10.Remove the one (1) screw holding the fan duct to the

oven cavity back plate.

11.Remove the fan duct from the oven.
12.Remove the fan duct 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 assembly from the shaft of

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

3) Now, the fan blade is free.