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R-962M - 17

 

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 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 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
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, 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.

R-962M - 18

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

"CONTROL PANEL REMOVAL".

3. Disconnect the all leads from the switches.
4. Remove each one (1) screw holding the upper latch hook

and lower latch hook to the oven cavity.

5. Remove the upper and lower latch hooks from the oven

cavity.

6. Push the monitored latch switch downwards with pushing

the retaining tab.

7. Push the monitor switch or stop switch rightwards with

pushing the retaining tab.

CAUTION: WHEN REMOVING THE SWITCH, DO NOT

BREAK THE TABS OF THE LATCH HOOKS.

1. CARRY OUT 3D CHECKS
2. Remove five (5) screws holding the upper and lower oven

hinge to the oven cavity.

3. Now, the lower oven hinge is free.
4. Separate the door assembly and upper oven hinge. Door

assembly is now free.

5. Re-install lower oven hinge to the new door assembly.
6. On re-installing new door assembly, secure the upper

and lower oven hinges with the five (5) mounting screws
to the oven cavity. Make sure the door is parallel with
bottom line of the oven face plate and the latch head pass
through the latch holes correctly.

7. CARRY OUT 4R CHECKS
Note: After any service to the door, the approved microwave

survey meter should be used to assure in compliance
with proper microwave radiation  standards. (Refer to
Microwave Measurement Procedure.)

1. Insert an iron plate (thickness of about 0.5mm) or flat type

screw driver to the gap between the choke cover and
door panel as shown in figure C-9 to free the engaging
part. The protect sheet may be used so as not to damage
the door panel.

2. Lift up the choke cover, now choke cove is free.

FLAT TYPE
SCREW-DRIVER

PROTECT BY TAPE

CHOKE
COVER

DOOR
PANEL

DOOR

RE-INSTALL

DOOR 
ASSEMBLY

SCREWS

SCREWS

UPPER
OVEN HINGE

OUTER CASE
CABINET

LOWER
OVEN HINGE

LATCH
HEADS

SW3 Monitor

 switch

SW1 Monitored
 latch switch

SW2 Stop
 switch

Tab

Tab

Tab

R-962M - 19

Remove the door assembly, referring  from item 1 through to

item 4 of “DOOR REPLACEMENT”.

1. Place the door assembly on a soft cloth facing up.
2. Remove the choke cover, referring to “CHOKE COVER

REMOVAL”.

3. Remove the eight (8) screws holding the door frame to

the door panel assembly.

4. Release the the door frame from door assembly. Now,

the door frame is free.

5. Remove the two (2) glass stopper holding door glass to

the door frame.

6. Slide the door glass to the up side until stopped by door

frame.

7. Lift up the door glass, now the door glass is free.

1. Remove the choke cover, referring to “CHOKE COVER

REMOVAL”.

2. Release the latch spring from the tabs of the door panel.
3. Release the latch spring from the latch head.
4. Release the latch head from the door panel.
5. Now, the latch head is free.

  Before carrying out any work carry out 3D checks

1)  

isconnect the supply.

2)  

oor opened, and wedged open

3)  

ischarge high voltage capactior

Ensure the following:

1.  Wires must not touch:

a)  High voltage parts.

(Magnetron, high voltage transformer, high voltage capacitor and high voltage rectifier assembly)

b)  Parts that become hot.

(Heating elements, oven lamp, oven cavity magnetron and high voltage transformer)

c)  Sharp edges

(Bottom plates, oven cavity, waveguide flange, chassis support and other metallic parts)

d)  Movable parts

(Fan blade, any motor, switch lever and open button)

2.  Positive lock connectors are fitted correctly.  Ensure the locking pin is located correctly.
3.  Wires are connected correctly as per pictorial diagram.
4.  No wire leads are trapped by the outer wrap.

R-962M - 20

After any repair, the microwave oven must be checked for
microwave leakage to ensure continued safe operation. BS
EN 60335-2-25 specifies that the maximum permitted leak-
age with a load of 275 ml is 50 W/m

2 

(equivalent to 5 mW/cm

2)

at  a distance of 5 cm from the oven.

The following items are required to carry out this test:-
1.  A low form of 600 ml beaker made from an electrically

non-conductive material, such as glass or plastic, with an
inside diameter of approximately 8.5 cm. This must
contain 275 

±

 15 ml of water, at an initial temperature of

20 

±

 2˚C.

2. A leakage detector which has been calibrated within the

preceding 12 months to a stand whose accuracy  can be
traced to National Physical Laboratory Standards.

Recommended instruments are:

Apollo "XI"
Celtec "A100"

Before commencing the test, check that the leakage detector
is functioning and adjusted according to the manufacturer's
instructions, and any spacers are fitted to ensure that meas-
urement is taken 5cm from the surface of the oven.

1. Place the beaker containing the water load in the oven

cavity at the centre of the turntable. The placing of this
standard load in the oven is important, not only to protect
the oven, but also to ensure that any leakage it is not
disguised by too large a load absorbing energy.

2. Close the oven door, and with the power level set to

FULL, turn the oven ON with the timer set for a few
minutes operation. Should the water begin to boil before
the test has been completed, it should be replaced.

3. As shown in the diagram below, move the probe slowly

(not faster than 2.5 cm/sec.);-

a) around the edge of the door following the gap
b) across the face of the door
c) across any vents in the oven's sides, rear or top

Dotted line indicates the path taken by the leakage detector.

Whilst the maximum leakage permitted in BS EN 60335-2-25 is 50 W/m

2 

(equivalent to 5 mW/cm

2

), it is not normal to detect

any significant leakage, and therefore any detected leakage should be investigated.