R-207 - Sharp Home Appliance Service Manual (repair manual). Page 13

11

In this service manual, troubleshooting by unit replacement is described according to the symptoms
indicated.
Control unit.
The following symptoms indicate a defective control unit.

a) When rotating the potentiometer, the power level can not be selected.
b) Cooking is not possible.

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between Pin No. 3 of the 2 pin connector (A) and the
common terminal of the relay RY1 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.

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. 12.0V D.C.

Oven lamp / Turntable motor / Fan motor

RY2

Approx. 11.0V D.C.

High voltage transformer

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.
CARRY OUT 3D CHECKS.

STEPS

OCCURRENCE

CAUSE OR CORRECTION

1

The rated voltage is not applied between Pin

Check supply voltage and oven power cord.

No. 3 of the 2 pin connector (A) and the
common terminal of the relay RY1.

2

Only pattern at “a” is broken.

*Insert jumper wire J1 and solder.

3

Pattern at “a” and “b” are broken.

*Insert the coil RCILF2003YAZZ between “c” and “d”.

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

a visual inspection of the varistor. Check
for burned damage. If any abnormal con-
dition is detected, replace the defective
control unit.

CARRY OUT 4R CHECKS.

D71

R75

(F1)

(J2)

D1

(J1)

D70