R-757M (serv.man17). Complete - Sharp Home Appliance Service Manual (repair manual). Page 13

R-757M - 13

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.

L (min)

Cx 

±

 20%

Cy 

±

 20%

1.0mH

0.22

µ

F

4700pF

Between N and L

Approx. 680 k

Ω

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit

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

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

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

Table: Resistance of Motor

Motors

Resistance

Fan motor

Approximately

290 

Ω

Turntable motor

Approximately 14.6 k

Ω

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

RED

WHT

L

L

R1

L

R2

N

Cx

Cy

20A

R1: 10M ohm 

±

 20%

R2: 680k ohm 

±

 20%

F8A

CARRY OUT 3D CHECKS.

Before carrying out the following tests make sure the heating element is cooled completely.

1. Resistance of heating element.

Disconnect the wire leads to the heating element to be tested.  Using ohmmeter with low resistance
range. Check the resistance across the terminals of the heating element as described in the
following table.

Table: Resistance of heating element

Parts name

Resistance

Grill heating element

Approximately 61 

Ω

2. Insulation resistance.

Disconnect the wire leads to the heating element to be tested. Check the insulation resistance
between the element terminal and cavity using a 500V - 100M

Ω

 insulation tester.  The insulation

resistance should be more than 10 M

Ω

 in the cold element.

If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably
faulty and should be replaced.

CARRY OUT 4R CHECKS.