Sharp R-380A, Service Manual

Page: 14 / 40

R-380A
12
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
this may be due to over heating produced by improper setting of the cooking time or failure of the
control panel.
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.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 390
Ω
Turntable motor Approximately 16.08 k
Ω
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS
H MOTOR WINDING TEST
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 2nd. latch 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.
3. If the fuse M8A is blown, there could be a short in the asymmetric rectifier or there could be a
ground in wire harness. A short in the asymmetric rectifier may have occured due to short or
ground in H.V. rectifier, magnetron, power transformer or H.V. wire. Check them and replace the
defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE FUSE M8A WITH THE CORRECT VALUE REPLACEMENT
I BLOWN FUSE F M8A
J 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.
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
N
L
Cx
L
L
Cy
WHT
RED
L (min) Cx
±
20% Cy
±
20%
600
µ
H 0.068
µ
F 0.0022
µ
F