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R-671M  -  13

CARRY OUT 3D CHECKS.

A. Isolate the high voltage capacitor from the circuit.
B. Continuity check must be carried out with measuring instrument which is set to the highest

resistance range.

C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M

Ω

 after

it has been charged.

D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10 M

Ω

 because of its internal 10M

Ω

resistance.

F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite when the capacitor is  normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the
following table.

Table: Terminal Connection of Switch

Plunger Operation

COM to NO

COM to NC

Released

Open circuit

Short circuit

Depressed

Short circuit

Open circuit

COM; Common terminal,
NO;

Normally open terminal

NC;

Normally close terminal

If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a continuity
test across the two terminals as described in the below.

Table: Thermal Cut-out Test

Temperature of "ON"

Temperature of "OFF"

Indication of ohmmeter

Parts Name

 condition  (closed circuit).

condition (open circuit).

(When room temperature

(˚C)

(˚C)

is approx. 20˚C.)

Thermal cut-out 145˚C

Cuts back in at 115˚C.

Above 145˚C

Closed circuit

Thermal cut-out 150˚C

Cuts back in at 130˚C.

Above 150˚C

Closed circuit

If incorrect readings are obtained, replace the thermal cut-out.

An open circuit thermal cut-out (HVT) indicates that the high voltage capacitor  has overheated, this may
be due to resistricted ventilation, cooling fan failure or a fault condition within the high voltage capacitor
or HV. circuit.

An open circuit thermal cut-out (OVEN) indicates that the food in the oven cavity may catch fire, this
may be due to over heating produced by improper setting of the cooking timer or failure of the control
panel.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

If the fuse 15A is blown, there could be 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.

R-671M  -  14

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 element (top)

Approximately 88 

Ω

Bottom heating element

Approximately 150 

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.

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.

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

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

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

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two
terminals as described in the table below.

Table: Resistance of Motor

Motors

Resistance

Fan motor

Approximately 300 

Ω

Turntable motor

Approximately 14.9 k

Ω

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

LINE BYPASS
CAPACITOR
4700p/250V

LINE BYPASS
CAPACITOR
4700p/250V

NOISE SUPPRESSION COIL

RESISTOR 680K/0.5W

10M/0.5W

LINE CROSS CAPACITOR
0.22

µ

/250V

FUSE 15A

FUSE F8A

NOISE 
FILTER

L

N

WHT

RED

R-671M  -  15

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 troubleshooting by unit 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 M) 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.

If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon is making
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 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 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.

MICROWAVE

POWER LEVEL

Kg / Lb

TIMER 

PIZZA

LESS

MORE

GRILL

BREAK

FAST

OVEN

CHIPS

DUAL

GRILL

START

AUTO MINUTE

AUTO START

CLOCK

BAKED

POTATOES

AUTO

COOK

AUTO

DEFROST

STOP/

CLEAR

MIXED

GRILL

1 min.

10 sec.

10 min.

Kg • Lb

g • oz

G 5

G 6

G 7

G 8

G 9

G10

G11

G12

G 4

G 3

G 2

G 1

R-671M  -  16

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 5 pin connector (A)  on the
control unit with an A.C. voltmeter.
The meter should indicate rated voltage, if not check oven circuit.

RY1, RY2, RY3, RY4, RY5 and RY6 Test
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking, grill cooking or dual
cooking 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. 24.0V D.C.

Oven lamp / Turntable motor

RY2

Approx. 18.0V D.C.

High voltage transformer

RY3

Approx. 24.0V D.C.

Top heating element

RY4

Approx. 30.0V D.C.

Bottom heating element

RY5

Approx. 24.0V D.C.

Fan motor

RY6

Approx. 24.0V D.C.

Touch control transformer

CARRY OUT 4R CHECKS.

To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary 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 at

Check supply voltage and oven power cord.

POWER terminal of CPU connector (CN-A).

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 a 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.

VRS1

CN - A

T1

1

(J1)

RY5