Sharp R-677W Service Manual page 16

PROCEDURE
LETTER
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 THERMAL CUT-OUT TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a
continuity test across the two terminals as described in the below.
Parts Name
Thermal cut-out 145˚C
Thermal cut-out 150˚C
If incorrect readings are obtained, replace the thermal cut-out.
An open circuit thermal cut-out TC1 (HVT) indicates that the high voltage transforner has overheated,
this may be due to resistricted ventilation, cooling fan failure or a fault condition within the high voltage
transformer or HV. circuit.
An open circuit thermal cut-out TC2 (OVEN) indicates that the food in the oven cavity may catch fire,
this may be due to over heating produced by improper setting of the cooking timer or failure of the
control panel.
CARRY OUT 4R CHECKS.
G BLOWN FUSE 20A (F1)
CARRY OUT 3D CHECKS.
If the fuse 15A is blown, there could be a shorts or a ground in electrical parts or wire harness. Check
them and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION:
H BLOWN FUSE F8A (F2)
CARRY OUT 3D CHECKS.
If the fuse F8A (F2) is blown when the door is opened, check the primary latch switch, monitor switch
and monitor resistor.
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:
TEST PROCEDURES
Table: Terminal Connection of Switch
COM to NO
Open circuit
Short circuit
Temperature of "ON"
condition (closed circuit).
(˚C)
Cuts back in at 115˚C.
Cuts back in at 130˚C.
Only replace fuse
Only replace fuse with the correct value replacement.
...
CONT
COMPONENT TEST
COM; Common terminal,
COM to NC
NO;
Short circuit
NC;
Open circuit
Table: Thermal Cut-out Test
Temperature of "OFF"
condition (open circuit).
(˚C)
Above 145˚C
Above 150˚C
20A with the correct value replacement.
R-677 - 16
Normally open terminal
Normally close terminal
Indication of ohmmeter
(When room temperature
is approx. 20˚C.)
Closed circuit
Closed circuit