Sharp R-3A88, Service Manual

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R-3A88
11
PROCEDURE
LETTER
COMPONENT TEST
TEST PROCEDURES (CONT'D)
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.
G MONITOR RESISTOR 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.
H MOTOR WINDING TEST
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 370
Ω
Turntable motor Approximately 16.08 k
Ω
If incorrect readings are obtained, replace the motor. CARRY OUT 4R CHECKS
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 relay control 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 divided into two units, Control Unit and Key
Unit, and troubleshooting by 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.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Panel
The following symptoms indicate a defective control unit. Before replacing the control unit,
perform the Key unit test (Procedure K) to determine if control unit is faulty.
2-1 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.