Sharp R-350J Service Manual page 12

R-350J
PROCEDURE
LETTER
C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MΩ after it has
been charged.
D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10 MΩ because of its internal 10MΩ resistance.
F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite when the capacitor is normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.
CARRY OUT 4R CHECKS.
E SWITCH TEST
CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following
table.
Plunger Operation
Released
Depressed
If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.
F TEMPERATURE FUSE TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the temperature fuse. Then using an ohmmeter, make a continuity
test across the two terminals as described in the table below.
CARRY OUT 4R CHECKS.
Parts Name
Temperature fuse 150˚C
If incorrect readings are obtained, replace the temperature fuse.
An open circuit temperature fuse (MG) indicates that the magnetron has overheated, this may be due to
resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV circuit.
An open circuit temperature fuse (OVEN) indicates that the foods in the oven may catch fire, this may be due
to over heating produced by improper setting of the cooking time or failure of the control panel.
G 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
H BLOWN FUSE F10A
CARRY OUT 3D CHECKS.
1. If the fuse F10A 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.
TEST PROCEDURES
Table: Terminal Connection of Switch
COM to NO
Open circuit
Short circuit
Table: Temperature fuse Test
Temperature of "ON" condition
(closed circuit) (˚C)
This is not resetable type.
Table: Resistance of Motor
Motors
Fan motor
Turntable motor
10
COMPONENT TEST
COM to NC COM; Common terminal
Short circuit NO;
Open circuit NC;
Temperature of "OFF" condition Indication of ohmmeter
(open circuit) (˚C)
Above 150˚C
Resistance
Approximately 250 Ω
Approximately 14.5 kΩ
Normally open terminal
Normally close terminal
(When room temperature
is approx. 20˚C)
Closed circuit.