Sharp R-950A Service Manual page 23

R-950A
PROCEDURE
LETTER
K 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.
CARRY OUT 4R CHECKS.
L 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.
If incorrect readings are obtained, replace the monitor resistor.
CARRY OUT 4R CHECKS.
M NOISE FILTER TEST.
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the noise
filter. Using an ohmmeter, check between the termi-
nals as described in the following table.
If incorrect readings are obtained, replace the noise
filter unit.
MEASURING POINT
Between N and L
Between terminal N and WHITE
Between terminal L and RED
CARRY OUT 4R CHECKS.
N 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 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.
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 Unit.
The following symptoms indicate a defective control unit. Replace the control unit.
TEST PROCEDURES
COMPONENT TEST
Table: Resistance of Motor
Motors
Fan motor
Turntable motor
Convection fan motor
Damper motor
The resistance of monitor resistor is approx. 0.8 ohms.
INDICATION OF OHMMETER
Open circuit
Short circuit
Short circuit
16
Resistance
Approximately 295 Ω
Approximately 19.2 kΩ
Approximately 210 Ω
Approximately 11 kΩ
NOISE FILTER
N
NOISE SUPPRESSION COIL
LINE CROSS CAPACITOR 0.22µ / AC 250V
LINE BYPASS CAPACITOR
LINE BYPASS CAPACITOR
0.0047µ /AC 250V 0.0047µ /AC 250V
WHT
L
FUSE
20A
RED