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R-953/963M - 15

CARRY OUT 3D CHECKS.

If the fuse 20A is blown, there is a shorts or grounds in electrical parts or wire harness. Check them and
replace the defective parts or repair the wire harness.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

1. If the fuse F8A  is blown when the door is opened, check the monitored latch switch and monitor

switch.

2. If the fuse F8A is blown by incorrect door switching replace the defective switch(es) and the  fuse

F8A.

3. If the fuse F8A is blown, there could be shorts in the asymmetric rectifier or there is a ground in wire

harness. A short in the asymmetric rectifier may be occurred due to short or ground in H.V. rectifier,
magnetron, high voltage transformer or H.V. wire. Check them and replace the defective parts or
repair the wire harness.

CARRY OUT 4R CHECKS.

Between N and L

Approx. 680 k

Ω

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit

If incorrect readings are absorbed, replace the noise filter unit.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Before carrying out the following tests make sure the heating element is cool completely.

1. Resistance of heating element.

Disconnect the wire leads to the heating element to be tested.  Using ohmmeter with low resistance
range. Check the resistance across the terminals of the heating element as described in the
following table.

Table: Resistance of heating element

Parts name

Resistance

Grill heating elements (top)

Approximately 44.4 

Ω

 (22.2 

Ω

 x 2)

Convection heating element

Approximately 42.5 

Ω

2. Insulation resistance.

Disconnect the wire leads to the heating element to be tested. Check the insulation resistance
between the element terminal and cavity using a 500V - 100M

Ω

 insulation tester.  The insulation

resistance should be more than 10 M

Ω

 in the cold start.

If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably
faulty and should be replaced.

CARRY OUT 4R CHECKS.

F8A

20A

WHT

RED

R1

R2

N

Cx

Cy

L

L

L

L (min)

Cx 

±

 20%

Cy 

±

 20%

1.0mH

0.22

µ

F

4700pF

R-953/963M - 16

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance can not be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key
Unit, and also the Control unit is divided into two units, CPU unit and Power unit, and troubleshooting
by replacement is described according to the symptoms indicated.
1.  Key Unit   Note : Check key unit ribbon connection before replacement.

The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.

2. Control Panel

The following symptoms indicate a defective control unit. Before replacing the control unit perform
the key unit test (Procedure N) to determine if control unit is faulty.

2-1  In connection with pads

a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.

2-2  In connection with indicators

a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light up.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.

2-3  Other possible troubles caused by defective control unit.

a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
d) Proper temperature measurement is not obtained.

If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable
is marking good contact, verify that the door sensing switch (stop switch) operates properly; that is the
contacts are closed when the door is closed and open when the door is open. If the door sensing switch
(stop switch) is good, disconnect the flat ribbon cable that connects the key unit to the control unit and
make sure the door sensing switch is closed (either close the door or short the door sensing switch
connecter). Use the Key unit matrix indicated on the control panel schematic and place a jumper wire
between the pins that correspond to the STOP/CLEAR pad marking momentary contact. If the control
unit responds by clearing with a beep the key unit is faulty and must be replaced. If the control unit does
not respond, it is faulty and must be replaced.  If a specific pad does not respond, the above method
may be used (after clearing the control unit) to determine if the control unit or key pad is at fault.

CARRY OUT 4R CHECKS.

G12

G11

G10

G 9

G 8

ROAST

POULTRY

ROAST

PORK

MINCED

MEAT

MORE

STEAK/
CHOPS

AUTO

COOK

KITCHEN

TIMER

Kg / Lb

10 sec.

1 min.

10 min.

GRILL

CHICKEN

PORTIONS

MICRO.

POWER

STOP

CLEAR

CONV.

(˚C)

LESS

UP

DOWN

DUAL

CONV./

GRILL

ROAST

BEEF/

LAMB

AUTO

START

AUTO

MINUTE

CLOCK

START

G 7

G 6

G 5

G 4

G 3

G 2

G 1

G12

G11

G10

G 9

G 8

ROAST

POULTRY

ROAST

PORK

MINCED

MEAT

CANNED

FOOD

MORE

STEAK/
CHOPS

FRESH

VEG.

RICE/

PASTA

KITCHEN

TIMER

Kg / Lb

10 sec.

1 min.

10 min.

GRILL

CHICKEN

PORTIONS

FRESH

FISH

AUTO

COOK

MICRO.

POWER

CONV.

(˚C)

STOP

CLEAR

LESS

UP

DOWN

info

DUAL

CONV./

GRILL

ROAST

BEEF/

LAMB

CHILLED

READY
MEALS

FROZEN

READY
MEALS

AUTO

START

AUTO

MINUTE

CLOCK

START

G 7

G 6

G 5

G 4

G 3

G 2

G 1

R-953/963M - 17

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on the
control unit with an A.C. voltmeter.
The meter should indicate 230-240 volts, if not check oven circuit.

Relay Test
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation, grill
operation, convection operation or dual operation.

DC. voltage indicated .......... Defective relay.
DC. voltage not indicated .... Check diode which is connected to the relay coil. If diode is good,

control unit is defective.

RELAY SYMBOL

OPERATIONAL VOLTAGE

CONNECTED COMPONENTS

RY1

Approx. 18.0V D.C.

Oven lamp / Turntable motor

RY2

Approx. 18.0V D.C.

High voltage transformer

RY3

Approx. 24.0V D.C.

Grill (Top) heating element

RY4

Approx. 24.0V D.C.

Convection heating element

RY5

Approx. 24.0V D.C.

Touch control transformer

RY6

Approx. 24.0V D.C.

Fan motor

RY7

Approx. 24.0V D.C.

Convection motor

RY8

Approx. 24.0V D.C.

Damper motor

CARRY OUT 4R CHECKS.

To protect the electronic circuits, this model is provided with a fine foil pattern added to the input circuit
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

STEPS

OCCURRENCE

CAUSE OR CORRECTION

1

The rated AC voltage is not present between

Check supply voltage and oven power cord.

Pin Nos. 1 and 3 of the 4-pin connector (E).

2

The rated AC voltage is present at primary

Low voltage transformer or secondary circuit defective.

side of low voltage transformer.

Check and repair.

3

Only pattern at "a" is broken.

*Insert jumper wire J1 and solder.
(CARRY OUT 3D CHECKS BEFORE REPAIR.)

4

Pattern at "a" and "b" are broken.

*Insert the coil RCILF2003YAZZ between "c" and "d".
(CARRY OUT 3D CHECKS BEFORE REPAIR.)

NOTE: *At the time of these repairs, make a

visual inspection of the varistor for
burning damage and examine the
transformer with tester for the pres-
ence of layer short circuit (check pri-
mary coil resistance). If any abnormal
condition is detected, replace the de-
fective parts.

CARRY OUT 4R CHECKS.

(J1)

(J2)

9

1

7

CN - E

CN - A

VRS1

R-953/963M - 18

Checking the initial sensor cooking condition
(1) The oven should be plugged in at least two minutes before sensor cooking.
(2) Room temperature should not exceed 35˚C.
(3) The unit should not be installed in any area where heat and steam are generated. The unit should

not be installed, for example, next to a conventional surface unit. Refer to the "INSTALLATION
Instructions" .

(4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To

permit adequate ventilation, be sure to install so as not to block these vents. There should be some
space for air circulation.

(5) Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any

moisture with a dry cloth or paper towel.

(6) The Sensor works with food at normal storage temperature. For example, chicken pieces would

be at refrigerator temperature and canned soup at room temperature.

(7) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The

sensor will detect the vapour given of by the spray and turn off before food is properly cooked.

(8) If the sensor has not detected the vapour of the food, ERROR will appear and the oven will shut

off.

Water load cooking test
Make sure the oven has been plugged in at least five minutes before checking sensor cook operation.
The cabinet should be installed and screws tightened.
(1) Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
(2) Place the container on the center of tray in the oven cavity.
(3) Close the door.
(4) Touch FRESH FISH pad. Now, the oven is in the sensor cooking condition and "FRESH FISH"

will appear in the display.

(5) The oven will operate for the first 16 seconds, without generating microwave energy.
NOTE: ERROR will appear if the door is opened or STOP/CLEAR pad is touched during first stage

of sensor cooking.

(6) After approximately 16 seconds, microwave energy is produced, and the display should start to

count down the remaining cooking time, and oven should turn off after water is boiling (bubbling).

If the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation
below.

To determine if the sensor is defective, the simplest method is to replace it with a new replacement
sensor.
(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Remove the AH sensor.
(4) Install the new AH sensor.
(5) Re-install the outer case.
(6) Reconnect the oven to the power supply and check the sensor cook operation proceed as follows:

6-1. Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.
6-2. Place the container on the center of tray in the oven cavity.
6-3. Close the door.
6-4. Touch FRESH FISH pad.
6-5. The control panel is in automatic sensor operation.
6-6. The display will start to count down the remaining cooking time, and the oven will turn off

automatically after the water is boiling (babbling).

If new sensor dose not operate properly, the problem is with the control unit.

(1) Disconnect oven from power supply and remove outer case.
(2) Discharge the high voltage capacitor.
(3) Disconnect the wire leads from the cook relay.
(4) Disconnect the sensor connector that is mounted to lower portion of control panel.
(5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.
(6) Reconnect the oven to the power supply and check the sensor cook operation, proceed as follows:

6-1. Touch FRESH FISH pad.
6-2. The control panel is in the sensor cooking operation.
6-3. After approximately 30 seconds, push plunger of select switch. This condition is same as

judgement by AH sensor.