Sharp R-3S68 Service Manual page 13

PROCEDURE
LETTER
G MONITOR RESISTOR TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the monitor resist. Using an ohmmeter and set on a low range. Check between
the terminals of the monitor resistor.
The resistance of monitor resistor is approx. 0.8 ohms.
If incorrect readings are obtained, replace the monitor resistor.
CARRY OUT 4R CHECKS.
H MOTOR WINDING TEST
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.
I BLOWN FUSE F M8A
CARRY OUT 3D CHECKS.
1. If the fuse M8A is blown, there could be shorts or ground in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
2. If the fuse M8A is blown when the door is opened, check the 1st. latch switch, 2nd. interlock relay,
2nd. interlock relaycontrol switch, monitor switch and monitor resistor.
If the fuse M8A is blown by incorrect door switching replace the defective switch(s) and the fuse M8A.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE FUSE M8A WITH THE CORRECT VALUE REPLACEMENT.
J TOUCH CONTROL PANEL ASSEMBLY TEST
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 in one unit, and troubleshooting by unit
replacement is described according to the symptoms indicated.
1. Tact Switch.
The following symptoms indicate a defective tact switch. Replace the tact switch.
a) When touching the tact switches, a certain tact switch produces no signal at all.
b) When touching the tact switches, sometimes a tact switch produces no signal.
2. Control Panel
The following symptoms may indicate a defective control unit. Before replacing the control unit,
perform the tact switch test (Procedure K) to determine if control unit is faulty.
2-1 In connection with tact switches.
a) When touching the tact switches, a certain group of tact switches do not produce a signal.
b) When touching the tact switches, no tact switches produce a signal.
TEST PROCEDURES (CONT'D)
COMPONENT TEST
Table: Resistance of Motor
Motors
Fan motor
Turntable motor
11
Resistance
Approximately 370 Ω
Approximately 16.08 kΩ
CARRY OUT 4R CHECKS
R-3S68