Sharp R-2S56 - Test Procedures; Thermal and Fuse Tests; Motor Winding Test; Fuse Test

R-2S56
13
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 330 Ω
Turntable motor Approximately 12 kΩ
PROCEDURE
LETTER
COMPONENT TEST
TEST PROCEDURES (CONT'D)
G TEMPERATURE FUSE OR THERMAL CUT-OUT TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the temperature fuse or thermal cut-out. Then using an
ohmmeter, make a continuit test across the two terminals as described in the 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)
Temperature fuse 150˚C This is not resetable type Above 150˚C Closed circuit.
Thermal cut-out 95˚C Below 75˚C Above 95˚C Closed circuit.
If incorrect readings are obtained, replace the temp. fuse or thermal cut-out.
An open circuit temperature fuse (MAG.) indicates that the magnetron has overheated, this may be due
to resistricted ventilation, cooling fan failure.
An open circuit temperature fuse (OVEN) indicates that the oven cavity has overheated, this may be due
to no load operation.
An open circuit thermal cut-out 95˚C indicates that the fan motor winding has overheated, this may be
due to resisted ventilation or locked cooling fan.
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.
H MOTOR WINDING TEST
If incorrect readings are obtained, replace the motor.
CARRY OUT
4R CHECKS.
I FUSE
CARRY OUT 3D CHECKS.
If the fuse is blown when the door is opened, check the 1st latch switch, 2nd latch switch, monitor switch
and monitor resistor.
If the fuse is blown by incorrect door switching replace the defective switch(s) and the fuse.
If the fuse is blown, there is a short in the asymmetric rectifier or there is a ground in wire harness. A short
in the asymmetric rectifier may be occured due to short or ground in H.V. rectifier, magnetron, power
transformer or H.V. wire. Check them and replace the defective parts or repair the wire harness.
If the fuse is blown, there is a shorts or grounds in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION: Only replace fuse with the correct value replacement.