R-1900M (serv.man7). Test Procedures - Sharp Home Appliance Service Manual (repair manual). Page 4

R1900M

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2. Before performing this test, make sure that the secondary interlock switches (1), (2) and the primary interlock relay RY1 are operating properly,

according to the above Switch Test Procedure. Disconnect the wire lead from the monitor switches (1), (2) (COM) terminals. Check the monitor
switches (1), (2) operation by using the ohmmeter as follows. When the door is open, the meter should indicate a closed circuit. When the monitor
switch actuator 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, the switch may be
defective. After testing the monitor switches, reconnect the wire lead to the monitor switch (COM) terminals and check the continuity of the monitor
circuit.

3. CARRY OUT 4R CHECKS.

1. CARRY OUT 3D CHECKS.

2. If the fuse F10 (1) or (2) is blown when the door is opened, check the primary interlock relay RY1, secondary interlock switches (1), (2) and moni-

tor switches (1), (2) according to the “TEST PROCEDURE” for those switches before replacing the blown fuse F10 (1) or (2).

CAUTION: CAUTION: BEFORE REPLACING A BLOWN FUSE F10 (1) OR (2), TEST THE PRIMARY INTERLOCK RELAY, SECONDARY INTER-

LOCK SWITCHES, DOOR SENSING SWITCH AND MONITOR SWITCHES FOR PROPER OPERATION.

3. If the fuse is blown, check the magnetron, high voltage capacitor, high voltage rectifier assembly, according to the “TEST PROCEDURE” before

replacing the blown fuse. Then replace the fuse.

4. CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

If the weak point is blown, the fan motor or exhaust fan could be locked or there could be a shorts in the fan motor or exhaust fan. Check them and
replace the defective parts.

CARRY OUT 4R CHECKS.

CAUTION: Only replace weak point with the correct value replacement.

CARRY OUT 3D CHECKS.

If the weak point is blown, there could be a 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 weak point with the correct value replacement.

1. CARRY OUT 3D CHECKS.

2. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the temperature of the temperature fuse reaches

specified temperature as shown below.

Magnetron temperature 
fuse (1)

150

°C

Non resetable type

EE1

Magnetron (1) Failure:
Test magnetron (1) and fan motor.

Magnetron temperature 
fuse (2)

EE2

Magnetron (2) Failure:
Test magnetron (2) and fan motor.

Magnetron temperature 
fuse (1), (2)

EE3

Magnetron (1), (2) Failure: Test magnetron (1), (2).
Check fan motor and ventilation opening.

Oven temperature fuse

120

°C

Non resetable type

Oven shut off

Food has been burned in oven.
Temperature of oven inside is very high.

Screw Driver

Ohmmeter

Monitor switch (2)

Latch hook

Monitor switch (1)