Sharp R-671(B) Service Manual page 18

TEST PROCEDURES
PROCEDURE
LETTER
If the fuse F8A (F2) is blown by incorrect door switching replace the defective switch(es) and the fuse
F8A (F2).
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-671 - 17
COMPONENT TEST
N
LINE CROSS CAPACITOR
0.22µ/250V
NOISE SUPPRESSION COIL
LINE BYPASS
CAPACITOR
4700p/250V
WHT
INDICATION OF OHMMETER
Resistance
Approximately 300 Ω
Approximately 14.9 kΩ
Approximately 76 Ω
Approximately 132 Ω
F1:
FUSE 15A
10M/0.5W
RESISTOR 680K/0.5W
LINE BYPASS
CAPACITOR
4700p/250V
RED
Approx. 680 kΩ
Short circuit
Short circuit
Resistance
L
NOISE
FILTER