R-765M (serv.man7). Test procedure - Sharp Home Appliance Service Manual (repair manual). Page 6

R-765M - 15

Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

STEPS

OCCURANCE

CAUSE OR CORRECTION

The rated AC voltage is not present at

1

POWER terminal of CPU connector (CN-A).

Check supply voltage and oven power cord.

The rated AC voltage is present at primary

Low voltage transformer or secondary circuit defective.

2

side of low voltage transformer.

Check and repair.

*Insert jumper wire J1 and solder.

3

Only pattern at "a" is broken.

(CARRY OUT 3D CHECKS BEFORE REPAIR)

*Insert the coil RCILF2003YAZZ between "c" and "d".

4

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

(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 presence of layer short-
circuit (check primary coil resistance). If
any abnormal condition is detected,
replace the defective parts.

CARRY OUT 4R CHECKS.

3. Close the door.
4. Reconnect the supply.
5. Check the voltage between Pin Nos. 1 and 3 of the 3 pin connector (A) on the control unit with

an A.C. voltmeter. The meter should indicate 230-240 volts, if not check oven circuit.

6. RY1, RY2 and RY3 TEST
   These are operated by D.C. voltage. Check voltage at the relay coil with a D.C. voltmeter during the

microwave cooking operation, grill cooking or dual grill 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. 18.0V D.C.

Oven lamp / Turntable motor / Cooling fan motor

RY2

APPROX. 24.0V D.C.

Grill heating element

RY3

APPROX. 18.0V D.C.

High voltage transformer

CN - A

AC

31

VRS1

(J1)