R-27STMA (serv.man8). Test Procedures - Sharp Home Appliance Service Manual (repair manual). Page 3

R27STMA

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 secondary interlock switch, primary 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.

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 Switch Unit, and also the Control Unit is divided into two units, CPU Unit and Power Unit, and troubleshooting by unit replace-
ment is described according to the symptoms indicated.

1. Switch Unit. Note: Check switch unit wire harness connection before replacement.

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

1) When touching the buttons, a certain button produces no signal at all.

2) When touching the buttons, sometimes a button produces no signal.

3) When rotating the TIMER/WEIGHT knob, the cooking time or the weight can not be input.

2. Control Unit.

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

1) In connection with buttons.

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

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

2) In connection with indicators.

a) At a certain digit, all or some segments do not light up.

b) At a certain digit, brightness is low.

c) Only one indicator does not light up. 

d) The corresponding segments of all digits do not light up; or they continue to light up.

e) Wrong figure appears.

f) A certain group of indicators do not light up.

g) The figure of all digits flicker.

Table: Resistance of Motor

Fan Motors

Turntable motor

Part Code

RMOTEA405WRZZ

RMOTDA289WRZZ

RMOTDA173WRE0

RMOTDA253WRZZ

Resistance

Approximately 388

Ω

Approximately 13.5k

Ω Approximately 12.2kΩ

Approximately 14.5k

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