Sharp R-763IN Service Manual page 16

TEST PROCEDURES
PROCEDURE
LETTER
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.
CARRY OUT 4R CHECKS
PARTS NAME
Condition
Temperature of "ON" condition
(closed circuit)
Temperature of "OFF" condition
(open circuit)
Indication of ohmmeter (When room
temperature is approx. 20°C.)
If incorrect readings are obtained replace the thermal cut-out.
An open circuit thermal cut-out (MG) indicates that magnetron has overheated, this may be due to
restricted ventilation, cooling fan failure or a fault condition within the magnetron or HV circuit.
An open circuit thermal cut-out (OVEN) indicates that the foods in the oven may have caught fire, this
may be due to over heating produced by improper setting of the cooking timer or failure of the control
panel.
G BLOWN FUSE 15A F2
CARRY OUT 3D CHECKS
If the fuse 15A is blown, there could be 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: Only replace fuse 15A with the correct value replacement
H BLOWN FUSE F8A F1
CARRY OUT 3D CHECKS
If the fuse F1 F8A is blown when the door is opened, check the monitored latch switch and monitor
switch.
If the fuse F1 F8A is blown by incorrect door switching replace the defective switch(s) and the fuse F1
F8A
BLOWN FUSE F1 F8A
If the fuse F1 is blown, there could be a short in the asymmetric rectifier or there is a ground in wire
harness. A short in the asymmetric rectifier may have occured due to short or ground in H.V. rectifier,
magnetron, power transformer or H.V. wire. Check them and replace the defective parts or repair the
wire harness.
CARRY OUT 4R CHECKS
CAUTION: Only replace fuse with the correct value replacement.
COMPONENT TEST
Table: Thermal Cut-out Test
THERMAL CUT-OUT
125°C (MAG)
This is not resetable type
Above 125°C
Closed circuit
R-763 -
14
THERMAL CUT-OUT
160°C (OVEN)
This is not resettable type
Above 160°C
Closed circuit