R-211M. Complete - Sharp Home Appliance Service Manual (repair manual). Page 6

6

211M -

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, troubleshooting by replacement is described according to the symptoms indicated.
1. Control Panel

The following symptoms indicate a defective control unit.

1-1  In connection with LEDs

a) At a certain LED, all or some LEDs do not light up.
b) At a certain LED, brightness is low.
c) Only one LED does not light up.
d) All or some LEDs continue to light up.
e) A certain group of LEDs do not light up.
f) The LEDs flicker.

1-2  Other possible troubles caused by defective control unit.

a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.
c) Cooking time can not be set.
d) Power level can not be set.

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between Pin Nos. 3 and 5 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.

Relay Test
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation. convection cooking operation
or grill 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. 12.0V D.C.

High voltage transformer

CARRY OUT 4R CHECKS.