Sharp R-880B Service Manual page 17

PROCEDURE
LETTER
G BLOWN FUSE M10A
CARRY OUT 3D CHECKS.
If the fuse M10A is blown when the door is opened, check the 1st. latch switch, 2nd. latch switch, monitor
switch and monitor resistor.
If the fuse M10A is blown, there could be a short or ground in electrical parts or wire harness. Check
them and replace the defective parts or repair the wire harness.
If the fuse M10A is blown, there could be a short in the asymmetric rectifier or there is a ground in wire
harness. A short in the asymmetric rectifier may be occurred due to short or ground in H.V. rectifier,
magnetron, high voltage transformer or H.V. wire. Check them and replace the defective parts or repair
the wire harness.
CARRY OUT 4R CHECKS.
CAUTION:
H BLOWN FUSE 15A
CARRY OUT 3D CHECKS.
If the fuse 15A is blown, there could be a short or ground in electrical parts or wire harness. Check them
and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION:
I NOISE FILTER TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of noise filter.
Using an ohmmeter, check between the terminals as
described in the following table.
If incorrect readings are absorbed, replace the noise filter unit.
CARRY OUT 4R CHECKS.
J 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.
K TOP HEATERS AND BOTTOM HEATER TEST
CARRY OUT 3D CHECKS.
Before carrying out the following tests make sure the heater is cool completely.
1. Resistance of heater.
Disconnect the wire leads to the heater to be tested. Using ohmmeter with low resistance range.
TEST PROCEDURES
Only replace fuse M10A with the correct value replacement.
Only replace fuse 15A with the correct value replacement.
MEASURING POINTS
Between N and L
Between terminal N and WHITE
Between terminal L and RED
Table: Resistance of Motor
Motors
Fan motor
Turntable motor
Convection motor
COMPONENT TEST
N
L
INDICATION OF OHMMETER
Approx. 680 k
Short circuit
Short circuit
Resistance
Approximately 290
Approximately 14 k
Approximately 293 k
15
WHT
RED
F8A
R-880B