Read Sharp R-291KM Service Manual online
[12] Procedure L: RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between the pin No.1 of connector CN-B and the oven side 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.
Remove the outer case and check voltage between the pin No.1 of connector CN-B and the oven side 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.
RY1 and RY3 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.
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 defec tive.
DC. voltage not indicated ............ Check diode which is connected to the relay coil. If diode is good, control unit is defec tive.
RELAY SYMBOL
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY2, RY3
Approx. 12.8 V D.C.
Oven lamp / Turntable motor / Cooling fan motor
RY1
Approx. 12.3V D.C.
High voltage transformer
CARRY OUT 4R CHECKS.
[13] Procedure M: PROCEDURES TO BE TAKEN WHEN THE THERMAL FUSE IN LOW
VOLTAGE TRANSFORMER ON THE PRINTED WIRING BOARD (PWB) IS OPEN
To protect the electronic circuits, this model is provided with a Thermal fuse in low voltage transformer on the PWB, follow
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Problem: POWER ON, indicator does not light up.
CARRY OUT 3D CHECKS.
Problem: POWER ON, indicator does not light up.
CARRY OUT 3D CHECKS.
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1
the pin No.1 of connector CN-B and the oven side terminal of
the relay RY1
Check supply voltage and oven power cord.
2
The rated AC voltage is present to primary side of low voltage transformer. Low voltage transformer or secondary circuit defective.
Check and replace the control unit.
R-291(K)M
8 – 5
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