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R-895M - 16

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of noise filter.
Using an ohmmeter, check between the terminals as
described in the following table.

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.

L (min)

Cx ± 20%

Cy ± 20%

R1

R2

1.0mH

0.22µF

4700pF

10 MΩ

680kΩ

Between N and L

Approx. 680 kΩ

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.

F8A

20A

WHT

RED

R1

R2

N

Cx

Cy

L

L

L

Table: Resistance of heating element

Parts name

Resistance

Grill heating element (top)

Approximately 48 Ω

Bottom heating element

Approximately 92 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 - 100MΩ insulation tester.  The insulation
resistance should be more than 10 MΩ 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.

R-895M - 17

The 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 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 ribbon cable is
making good contact, verify that the stop switch operates properly; that is the contacts are closed when
the door is closed and open when the door is open. If the stop switch is good, disconnect the flat ribbon
cable that connects the key unit to the control unit and make sure the stop switch is closed (either close
the door or short the stop 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 making
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 a 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.

G 9

G10

G11

G12

Pie/

Quiche

Ready

Meals

Rice/

Pasta

Italian

Dish

Indian

Dish

Roast

Pork

Chinese

Dish

Crispy

Potatoes

Roast

Beef/

Lamp

Crispy

Crumb

Foods

DUAL

CONV. /

GRILL

Roast

Poultry

POWER

LEVEL

STOP

CLEAR

PIZZA

Desserts

10sec.

1min.

10min.

GRILL BREAKFAST

MORE

Chicken

Quarters

Whole

Poultry

CONV

(˚C)

Meat

Joint

G 8

G 7

G 6

G 5

G 4

G 3

G 2

G 1

UP

LESS

DOWN

info

START

AUTO MINUTE

KITCHEN TIMER

CLOCK SET

R-895M - 18

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.

Bottom 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

CARRY OUT 4R CHECKS..

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 dam-
age and examine the transformer with tester
for the presence of layer short circuit (check
primary coil resistance).

If any abnormal condition is detected, re-
place the defective parts.

CARRY OUT 4R CHECKS.

CN-A

CN-E

D12

7

(J1)

D13

VRS1

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

R-895M - 18

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.

Bottom 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

CARRY OUT 4R CHECKS..

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 dam-
age and examine the transformer with tester
for the presence of layer short circuit (check
primary coil resistance).

If any abnormal condition is detected, re-
place the defective parts.

CARRY OUT 4R CHECKS.

CN-A

CN-E

D12

7

(J1)

D13

VRS1

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