Sharp R-8380 Service Manual page 17

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TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
F MONITOR SWITCH TEST
Disconnect oven from power supply. Disconnect the lead wire to the monitor switch. Connect
one ohmmeter lead to NC terminal of monitor switch, and the other lead to COM terminal of
monitor switch, as shown figure. When the door is opened, the meter should indicate a close
circuit. When the plunger of monitor switch is pushed by a screw-driver through the latch hook
hole on the front plate of the oven cavity with the door opened, the meter should indicate an
open circuit. In case improper operation is indicated, replace the defective monitor switch. After
testing moniter switch, re-connect the wire leads to the monitor switch.
G
FUSE M8A
If the fuse in the monitor switch circuit is blown when the door is opened, check the upper latch
switch, lower latch switch and monitor switch according to the Test Procedure for those
switches, before replacing the blown fuse.
If the fuse is blown by improper switch operation, replace the defective switch and fuse at the
same time.
Replace just the fuse if the switches operate normally.
CAUTION; REPLACEMENT FUSE MUST BE THE L&TED FUSE IN PARTS LIST.
H OVEN THERMAL CUT-OUT TEST
t
Oven thermal cut-out is thermal cut-out. A continuity check across the thermal cut-out terminals
should indicaeflosed circuit unless the temperature of the oven thermal cu.+oGf%aches
approximately 104 "C. The thermal cut-out closes automatically at approximatefyy,C,j If im-
proper operatjonis'indicated replace thermal cut-out.
When the oven thermal cut-out opens, it indicates overheating of the heater duct. Check the
convection motor and convection fan or check if the ventilation openings are not blocked.
I
MAGNETRON TEMP. FUSE TEST
A continuity check across the temp. fuse terminals should indicate a closed circuit.
If the temperature of the magnetron reaches 145 "C, the temp. fuse opens. If the temp. fuse has
opened, replace the fuse. An open temp. fuse indicates overheating of the magnetron assembly.
Check for restricted air flow to the magnetron through the opening in the chassis, especially the
fan duct. Or an open temp. fuse indicates stop of fan motor. Check for fan motor.
J FAN THERMAL CUT-OUT TEST
Fan thermal cut-out is thermal cut-out. A continuity check across the thermal cut-out terminals
should indicate an closed circuit unless the temperature of the thermal cut-out reaches approxi-
mately 104 "C. The thermal cut-out closes automatically at approximately 84 "C. If improper
operation is indicated replace thermal cut-out.
When the fan thermal cut-out opens, it indicates overheating of the cooling fan motor. Check the
cooling fan motor or check if the ventilation openings are not blocked.
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