Sharp R-90GCH Service Manual page 20

R-90GCH
PROCEDURE
LETTER
M TOP HEATING ELEMENT H1 TEST
1. CARRY OUT 3D CHECKS.
2. Make sure the heating element is fully cooled and test as follows;
a. Disconnect wire leads from the heating element and measure the resistance with an ohmmeter.
On the R x 1 scale, the resistance between the heating element terminals should be approximately
34Ω.
b. Disconnect wire leads from the heating element and measure the insulation resistance with
500V - 100MΩ insulation resistance meter. The insulation resistance between heating element
terminal and cavity should be more than 0.5MΩ.
3. If the meter does not indicate above resistance, replace the top heating element.
4. CARRY OUT 4R CHECKS.
N SIDE HEATING ELEMENT H2 TEST
1. CARRY OUT 3D CHECKS.
2. Make sure the heating element is fully cooled and test as follows;
a. Disconnect wire leads from the heating element and measure the resistance with an ohmmeter. On the
R x 1 scale, the resistance between the heating element terminals should be approximately 43 Ω.
b. Disconnect wire leads from the heating element and measure the insulation resistance with
500V - 100MΩ insulation resistance meter. The insulation resistance between heating element
terminal and cavity should be more than 0.5MΩ.
3. If the meter does not indicate above resistance, replace the side heating element.
4. CARRY OUT 4R CHECKS.
O THERMISTOR TEST
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.
4. If the meter does not indicate above resistance, replace the thermistor.
5. CARRY OUT 4R CHECKS.
P DAMPER MOTOR DM TEST
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.
Q DAMPER SWITCH SW5 TEST
1. CARRY OUT 3D CHECKS.
TEST PROCEDURES
COMPONENT TEST
Room Temperature
68˚F(20˚C) - 86˚F(30˚C)
18
Resistance
Approx. 360 kΩ - 152 KΩ