R-465 (serv.man3). Troubleshooting guide and test procedure - Sharp Home Appliance Service Manual (repair manual). Page 4

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If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a
continuity test across the two terminals as described in the table below.

 CARRY OUT 4R CHECKS.

Table: Thermal cut-out Test

Temperature of "ON" condition

Temperature of  "OFF" condition

Indication ofohmmeter

Parts Name

(closed circuit) (˚C)

(open circuit) (˚C)

(When room temperature

 is approx. 20˚C)

Thermal cut-out 125˚C

This is not resetable type.

Above 125˚C

Closed circuit.

If incorrect readings are obtained, replace the thermal cut-out.

An open circuit thermal cut-out 125˚C (MG) indicates that the magnetron has overheated, this may
be due to resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV
circuit.

An open circuit thermal cut-out 125˚C (OVEN) indicates that the foods in the oven may catch fire, this
may  be due to over heating produced by improper setting of the cooking time or failure of the control
panel.

CARRY OUT 3D CHECKS.

Disconnect the leads from the monitor resistor. Using an ohmmeter and set on a low range. Check
between the terminals of the monitor resistor.

The resistance of monitor resistor is approx.  0.8 ohms.

If incorrect readings are obtained, replace the monitor resistor.

 CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

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 400 

Ω

Turntable motor

Approximately 12 k

Ω

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS

CARRY OUT 3D CHECKS.

1. If the fuse F10A is blown, there could be shorts or ground in electrical parts or wire harness.

Check them and replace the defective parts or repair the wire harness.

2. If the fuse F10A is blown when the door is opened, check the 1st. interlock switch, relay RY1,

monitor switch and monitor resistor.