Sharp R-671(B)M Service Manual page 14

TEST PROCEDURES
PROCEDURE
LETTER
H BLOWN FUSE F8A
CARRY OUT 3D CHECKS
If the fuse F8A is blown when the door is opened, check the primary latch switch, monitor switch and
monitor resistor.
If the fuse F8A is blown by incorrect door switching replace the defective switch(es) and the fuse F8A.
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 GRILL HEATING ELEMENT (TOP) AND BOTTOM HEATING ELEMENT TEST
CARRY OUT 3D CHECKS.
Before carrying out the following tests make sure the heating element is cool completely.
1. Resistance of heating element.
Disconnect the wire leads to the heating element to be tested. Using ohmmeter with low resistance
range. Check the resistance across the terminals of the heating element as described in the
following table.
2. Insulation resistance.
Disconnect the wire leads to the heating element to be tested. Check the insulation resistance
between the element terminal and cavity using a 500V - 100MΩ insulation tester. The insulation
resistance should be more than 10 MΩ in the cold start.
If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably
faulty and should be replaced.
CARRY OUT 4R CHECKS.
...
CONT
Only replace fuse 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
Table: Resistance of heating element
Parts name
Grill heating element (top)
Bottom heating element
R-671M - 14
COMPONENT TEST
N
LINE CROSS CAPACITOR
0.22µ/250V
WHT
INDICATION OF OHMMETER
Approx. 680 kΩ
Short circuit
Short circuit
Resistance
Approximately 300 Ω
Approximately 14.9 kΩ
Approximately 88 Ω
Approximately 150 Ω
L
FUSE 15A
NOISE
FILTER
10M/0.5W
NOISE SUPPRESSION COIL
RESISTOR 680K/0.5W
LINE BYPASS LINE BYPASS
CAPACITOR CAPACITOR
4700p/250V 4700p/250V
RED
Resistance