Sharp R-290H, Service Manual

Page: 12 / 36

R-290H(S)
10
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
D HIGH VOLTAGE CAPACITOR TEST
CARRY OUT 3D CHECKS.
A. Isolate the high voltage capacitor from the circuit.
B. Continuity check must be carried out with measuring instrument which is set to the highest
resistance range.
C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M
Ω
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 M
Ω
because of its internal 10M
Ω
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
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in
the following table.
CARRY OUT 3D CHECKS.
Table: Terminal Connection of Switch
Plunger Operation COM to NO COM to NC
Released O.C. S.C.
Depressed S.C. O.C.
COM; Common terminal,
NO; Normally open terminal
NC; Normally close terminal
S.C.; Short circuit
O.C.; Open circuit
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 below.
Table:
Temperature Fuse
Test
Temperature of "ON" Temperature of "OFF" Indication of ohmmeter (When room
Parts Name condition (closed circuit). condition (open circuit). temperature is approx. 20˚C.)
Temperature fuse 120˚C This is not resetable type. Above 120˚C Closed circuit
If incorrect readings are obtained, replace the temperature fuse.
An open circuit temperature fuse (OVEN) indicates that the food in the oven cavity may catch fire,
this may be due to overheating produced by improper setting of the cooking time or failure of the
control panel.
CARRY OUT 4R CHECKS.
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.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 400 ohms
Turntable motor Approximately 14.8 kohms
If incorrect readings are obtained, replace the motor. CARRY OUT 4R CHECKS.