Read Sharp R-22AMM (serv.man7) Service Manual online
R22AMM
7 – 6
[16] P: RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 3 and 5 of the connector (A) on the control unit with an A.C. voltmeter. The meter should
indicate 230 - 240 volts, if not check control unit circuity.
indicate 230 - 240 volts, if not check control unit circuity.
RY1, RY3 and RY4 Relay Test
These relays are operated by D.C. voltage. 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.
CARRY OUT 4R CHECKS.
[17] Q: PROCEDURES TO CHECK THE CONTROL UNIT
When the indicator does not light up, follow the troubleshooting guide given below for repair.
CARRY OUT 3D CHECKS.
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 pres-
ence of layer short-circuit (check primary coil resistance). If any abnormal condition is detected, replace the defective parts.
CARRY OUT 4R CHECKS.
RELAY SYMBOL
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
APPROX. 25.9V D.C.
Oven lamp, Blower motor and Antenna motors
RY3
APPROX. 25.9V D.C.
High voltage transformer (T1)
RY4
APPROX. 25.9V D.C.
High voltage transformer (T2)
STEPS
OCCURRENCE
CAUSE OR CORRECTION
1
The rated AC voltage is not present at POWER terminal of
CPU connector (CN-A).
CPU connector (CN-A).
Check supply voltage and oven power cord.
2
The rated AC voltage is present at primary side of touch con-
trol transformer.
trol transformer.
Touch control transformer or secondary circuit defective. Check and
repair.
repair.
