R-238ASL (serv.man8). Test Procedures - Sharp Home Appliance Service Manual (repair manual). Page 3

R238A(SL)

8 – 3

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.

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

If the fuse T6.3A is blown when the door is opened, check the 1st. latch switch, rely (RY1), 2nd. interlock relay (RY2) and monitor switch.

If the fuse T6.3A is blown by incorrect door switching replace the defective switch(es) and the fuse T6.3A.

If the fuse T6.3A 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 T6.3A WITH THE CORRECT VALUE REPLACEMENT.

CARRY OUT 3D CHECKS.

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

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

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.

Check them and replace the defective parts and the high voltage fuse.

CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE REPLACEMENT. 

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, the touch control panel assembly is divided into two
units, Control Unit and Key Unit, and also the Control Unit is divided into two units, CPU Unit and Power Unit, and troubleshooting by unit replacement
is described according to the symptoms indicated.

1. Key Unit. Note: Check key unit ribbon connection before replacement.

The following symptoms indicate a defective key unit. Replace the key unit.

1) When touching the pads, a certain pad produces no signal at all.

2) When touching a number pad, two figures or more are displayed.

3) When touching the pads, sometimes a pad produces no signal.

2. Control Unit.

The following symptoms indicate a defective control unit. Before replacing the control unit, perform the Key unit test (Procedure L) to determine if
control unit is faulty. 

1) In connection with pads.

a) When touching the pads, a certain group of pads do not produce a signal.                                                                                                                                                     

b) When touching the pads, no pads produce a signal.

2) In connection with indicators.

Table: Resistance of Motor

Motors

Resistance

Fan motor

Approximately 250 

Ω

Turntable motor

Approximately 14.7 k

Ω

MEASURING POINT 

INDICATION OF OHMMETER

Between N and L 

Open circuit

Between terminal N and WHITE 

Short circuit

Between terminal L and RED 

Short circuit

RED

WHT

FUSE

T6.3A

N

L

NOISE SUPPRESSION COIL

NOISE FILTER