Sharp R-933 Service Manual page 19

PROCEDURE
LETTER
An open circuit thermal cut-out (MG) TC1 indicates that the magnetron has overheated, this may be
due to resistricted ventilation, cooling fan failure.
An open circuit thermal cut-out (GRILL) TC2 indicates that the oven cavity has overheated, this may
be due to no load operation..
An open circuit thermal cut-out (CONV.) TC3 indicates that the convection fan winding has overheated,
this may be due to resistricted ventilation or locked cooling fan or locked convection fan motor.
CARRY OUT 4R CHECKS.
H 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.
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 BLOWN FUSE F1 20A
CARRY OUT 3D CHECKS.
If the fuse F1 20A is blown, there is a shorts or grounds in electrical parts or wire harness. Check them
and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION:
K BLOWN FUSE F2 F8A
CARRY OUT 3D CHECKS.
1. If the fuse F2 F8A is blown when the door is opened, check the monitored latch switch SW1 and
monitor switch SW3.
2. If the fuse F2 F8A is blown by incorrect door switching replace the defective switch(es) and the fuse
F2 F8A.
TEST PROCEDURES
Table: Resistance of Motor
Motors
Fan motor
Turntable motor
Convection fan motor
Damper motor
MEASURING POINTS
Between N and L
Between terminal N and WHITE
Between terminal L and RED
Only replace fuse with the correct value replacement.
COMPONENT TEST
Resistance
Approximately
Approximately
Approximately
Approximately
F1
L
20A
Cx
N
F2
F8A
Cx ± 20%
L (min)
1.0mH 0.22µF
INDICATION OF OHMMETER
17
293 Ω
15 kΩ
288 Ω
11 kΩ
WHT
L
L
R2
Cy
Cy ± 20%
R1 R2
4700pF 10MΩ 680kΩ
Approx. 680 kΩ
Short circuit
Short circuit
R1
RED