Sharp R-930CS Service Manual page 20

R-930CS
PROCEDURE
LETTER
L THERMISTOR TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect connector-E from the control unit. Measure the resistance of the thermistor with an
ohmmeter. Connect the ohmmeter leads to Pin No's E-3 and E-4.
5. If the meter does not indicate above resistance, replace the thermistor.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
M DAMPER MOTOR TEST
When the power cord is plugged into the wall receptacle and 120 volts A.C. is supplied to the damper
motor, the motor operates until the damper is opened and the damper switch closes. Then the damper
motor stops operation.
If the damper motor does not operate, check for A.C. voltage with a voltmeter at the motor.
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Ensure that the leads remain isolated from other components and oven chassis by using insulation
tape.
6. Disconnect the wire leads of motor and connect the meter leads to the wire leads of main wire harness.
7. Re-connect the power cord into the wall receptacle.
8. If 120 volts A.C. is indicated at the wire leads, replace the motor and if 120 volts A.C. is not indicated,
check the wire harness and control unit.
9. Disconnect the power supply cord, and then remove outer case.
10.Open the door and block it open.
11.Discharge high voltage capacitor.
12.Reconnect all leads removed from components during testing.
13.Re-install the outer case (cabinet).
14.Reconnect the power supply cord after the outer case is installed.
15.Run the oven and check all functions.
N DAMPER SWITCH TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.
6. Disconnect the wire leads from the switch terminals and connect ohmmeter leads to the common
(COM.) and normally open (N.O.) terminals of the switch.
6-1. When switch actuator is pushed by the damper motor cam, the meter should be indicated a closed
circuit.
6-2. When power cord is plugged into the wall receptacle, the damper motor operates and damper cam will
start to rotate. When the switch actuator is released, the meter should be indicated an open circuit.
7. If improper operation is indicated, replace the damper switch.
8. Disconnect the power supply cord, and then remove outer case.
TEST PROCEDURES
COMPONENT TEST
Room Temperature
68˚F(20˚C) - 86˚F(30˚C)
18
Resistance
Approx. 350k - 155K