Sharp R-950A, Service Manual

Page: 23 / 43

R-950A
16
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
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.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 295
Ω
Turntable motor Approximately 19.2 k
Ω
Convection fan motor Approximately 210
Ω
Damper motor Approximately 11 k
Ω
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
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.
L MONITOR RESISTOR TEST
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.
FUSE
20A
L
N
LINE CROSS CAPACITOR 0.22
µ
/ AC 250V
NOISE SUPPRESSION COIL
LINE BYPASS CAPACITOR
0.0047
µ
/AC 250V
LINE BYPASS CAPACITOR
0.0047
µ
/AC 250V
NOISE FILTER
WHT
RED
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
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 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.
N TOUCH CONTROL PANEL ASSEMBLY TEST