R-334 (serv.man4). Complete - Sharp Home Appliance Service Manual (repair manual). Page 17

R-334 - 17

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 below.

CARRY OUT 4R CHECKS

Temperature of ”ON” condition (closed circuit) ...................................................................

 This is not resetable type

Temperature of ”OFF” condition (open circuit) ....................................................................................

 Above 125

°

C

Indication of ohmmeter (When room temperature is approx. 20

°

C.) ........................................................

 Closed circuit

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

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

An open circuit thermal cut-out (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 timer or failure of the control panel.

CARRY OUT 3D CHECKS

1. If the special fuse F1 is blown, there could be shorts or grounds in electrical parts or wire harness.

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

2. If the special fuse F1 is blown, there could be a short in the asymmetric rectifier or there is a ground

in wire harness.  A short in the asymmetric rectifier may have occurred 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.

3. If the fuse  F1  8A is blown when the door is opened, check the primary latch switch and monitor switch.

If the fuse F1  8A is blown by incorrect door switching replace the defective switch(s) and the fuse
F1  8A.

CARRY OUT 4R CHECKS

CARRY OUT 3D CHECKS

Disconnect the leads from the terminals of
the noise filter.
Using an ohmmeter, check between the ter-
minals as described in the following table.

Between N and L

>100M

Ω

 ohm

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit

.ssp If incorrect readings are obtained, replace the noise filter unit.

CARRY OUT 4R CHECKS

L(min)

Cx 

±

 20%

Cy 

±

 20%

1mH

0.22

µ

F

0.0033

µ

F

RED

WHT

L

L

L

F8A

N

Cx

Cy

R2

R1

R1 = 10M

Ω

 

±

 5%

R2 = 680K

Ω

 

±

 5%