R-8000GK - Sharp Home Appliance Service Manual (repair manual). Page 15

13

Checking with a high ohm scale, if the capacitor is normal, the meter will indicate continuity for a short time
and should indicate an open circuit once the capacitor is charged. If the above is not the case, check the
capacitor with an ohmmeter to see if it is shorted between the terminals. If it is shorted, replace the capacitor.

3. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Disconnect the 3-pin connector of the jet motor from the main wire harness.
4. Measure the resistance of the jet motor with an ohmmeter.

The resistance of the main coil, across the black and the red wires, should be approximately 130 ohms. The
resistance of the sub coil, across the black and the white wires, should be approximately 140 ohms.

5. Also, the jet motor has the thermal cut-out in it.

Measure the resistance of the main coil (or the sub coil). The resistance across the black and the red wires
(or across the black and the white wires) should be
above resistance unless the temperature of the thermal
cut-out reaches approximately 130˚C. The thermal
cut-out resets automatically at 100˚C. If an ohmmeter
indicates an open circuit under normal condition,
replace the jet motor because the thermal cut-out has
opened. An open thermal cut-out indicates overheating
of the jet motor. Check for restricted air flow to the jet
motor or a lock of the convection fan, especially the
fan motor (high voltage transformer side).

6. CARRY OUT 4R CHECKS.

It is difficult to measure the exact temperature in the convection oven. An accurate thermocouple type
temperature tester must be used. A low priced bi-metal type thermometer is not reliable or accurate.
The temperature should be checked with outer case cabinet installed, approx. 5 minutes after preheat
temperature is reached (audible signal sounds four times). The temperature experienced may be approx. 17˚C
more or less than indicated on the display, however, in most cases the food cooking results will be satisfactory.
Difference in power supply voltage will also affect the oven temperature. The Household power supply voltage may
sometimes become lower than the rated voltage and cause under-cooking. If the power supply voltage is 10% lower
than the rated voltage, longer cooking time is required by 10% to 20%.

1. CARRY OUT 3D CHECKS.
2. Remove the back plate from the oven, referring to “BACK PLATE REMOVAL”.
3. Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals

as described in the table below.

Table: Resistance of Motor

Motors

Resistance

Fan motor

Approximately 77 

Ω

Turntable motor

Approximately 12 k

Ω

If incorrect readings are obtained, replace the motor.
4. CARRY OUT 4R CHECKS.

BLK

RED

WHT

Main Coil

3-pin 
Connector

Sub Coil

Thermal

Cut-out

130ßC OFF
100ßC ON

130‰

140‰

JET MOTOR

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike
conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter.
In this service manual, troubleshooting by unit replacement is described according to the symptoms indicated.

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