Sharp Sharp Microwave Oven r-8580 : User's Manual : Page 17

R-8580

TEST PROCEDURES (CONT’D)

PROCEDURE

LETTER

COMPONENT TEST

MONITOR SWITCH TEST

Before performing this test, disconnect oven from power supply and make sure that the upper

latch switch is operating properly referring to the above Switch Test Procedure.

Disconnect the wire lead from the monitor switch (NC) terminal.

Check the monitor switch operation by using the ohmmeter as follows.

When the door is open, the meter should indicate a closed circuit.

When the monitor switch actuater is pushed by a screw driver through the upper latch hole on

the front plate of the oven cavity with the door opened (in this condition the plunger of the

monitor switch is pushed in), the meter should indicate an open circuit.

If improper operation is indicated, replace the defective switch..

After testing the monitor switch, re-connect the wire lead to the monitor switch (NC) terminal.

SCREW.

\

UPPER ’

LACCH

HOLE

G

BLOWN FUSE

If the fuse in the upper latch-monitor switch circuit is blown when the door is opened, check the

upper latch switch and monitor switch according to the Test Procedure for those switches, before

replacing the blown fuse.

If the fuse is replaced, the monitor switch should be replaced at the same time.

If the fuse is blown by improper switch operation, adjust or replace the defective switch, fuse at

the same time.

Replace the fuse and monitor switch, even if the switches operate normally

CAUTION; REPLACEMENT FUSE MUST BE THE LISTED FUSE IN PARTS LIST.

H

TEMP. FUSE TEST

A continuity check across the temp. fuse terminals should indicate a closed circuit.

If the temperature of the magnetron reaches 142 ‘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

cooling duct and tolling fan.

I

THERMAL CUT-OUT

A continuity check across the thermal cut-out terminals should indicate a closed circuit unless

the temperature of the thermal cut-out reaches approximately 140 “C. The termal cut-out resets

automatically at approximately 115 “C.

If the thermal cut-out has opened under the normal condition, replace the same one is parts list.

An open thermal cut-out indicates overheating of the heater unit. Check for restricted air flow

to the heater unit through the vent holes of the oven cavity, especially the heater duct and con-

vection fan

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