R-90GCK (serv.man7). Test procedure - Sharp Home Appliance Service Manual (repair manual). Page 5

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b. Disconnect wire leads from the heating element  and measure the insulation resistance with

500V - 100M

Ω

 insulation resistance meter. The insulation resistance between heating element

terminal and cavity should be more than 0.5M

Ω

.

3. If the meter does not indicate above resistance, replace the side heating element.
4. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. 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-5 and E-6.

Room Temperature

Resistance

68˚F(20˚C) - 86˚F(30˚C)

Approx. 360 k

Ω

 - 152 K

Ω

4. If the meter does not indicate above resistance, replace the thermistor.

5. CARRY OUT 4R CHECKS.

When the power cord is plugged into the wall receptacle and the rated voltage 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. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Disconnect the leads to the primary of the high voltage transformer.
4. Ensure that the leads remain isolated from other components and oven chassis by using insulation

tape.

5. Disconnect the wire leads of motor and connect the meter leads to the wire leads of main wire

harness.

6. Reconnect the power cord into the wall receptacle.
7. If the rated voltage is indicated at the wire leads, replace the motor and  if the rated voltage is not

indicated, check the wire harness and control unit.

8. Disconnect the oven from power supply.
9. Open the door and wedge it open.
10.Discharge high voltage capacitor.
11.CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Disconnect the leads to the primary of the high voltage transformer.
3. Ensure that the leads remain isolated from other components and oven chassis by using insulation

tape.

4. 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.

4-1. When switch actuator is pushed by the damper motor cam, the meter should be indicated a

closed circuit.

4-2. 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.

5. If improper operation is indicated, replace the damper switch.
6. Disconnect the oven from power supply, and then remove outer case.
7. Open the door and wedge it open.
8. Discharge high voltage capacitor.
9. CARRY OUT 4R CHECKS.