E: Switch Test; F: Monitor Switch Test; G: Thermistor Test; H: Thermal Cut-Out Test - Sharp AX-1100 Service Manual

[5] 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 Common terminal to Normally open terminal
Released
Depressed
If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.

[6] F: MONITOR SWITCH TEST

CARRY OUT 3D CHECKS.
Before performing this test, make sure that the monitored interlock switch and the relay RY-4 on the control unit are operating properly, according to
the above Switch Test Procedure. Disconnect the wire lead from the monitor switch (COM) 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 actuator is pushed by a screw driver
through the right 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 switch, reconnect
the wire lead to the monitor switch (COM) terminal and check the continuity of the monitor circuit.
CARRY OUT 4R CHECKS.

[7] G: THERMISTOR TEST

CARRY OUT 3D CHECKS.
Disconnect the thermistor from the control unit. Measure the resistance of the thermistor with an ohmmeter.
Room Temperature
Resistance Approximately 200 k
If the meter does not indicate above resistance, replace the thermistor.
CARRY OUT 4R CHECKS.

[8] H: 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 TC1 145C
Thermal cut-out TC2, TC3
If incorrect readings are obtained, replace the thermal cut-out.
An open circuit thermal cut-out (MG) TC1 indicates that the magnetron has overheated, this may be due to resistricted ventilation, cooling fan failure.
An open circuit thermal cut-out (OVEN) TC2 indicates that the oven cavity has overheated, this may be due to no load operation or fire in the oven
cavity.
An open circuit thermal cut-out (Engine) TC3 indicates that the engine unit has overheated, this may be due to empty water tank or pump motor fail-
ure.
CARRY OUT 4R CHECKS.

[9] I: BLOWN FUSE (F1) 20A

CARRY OUT 3D CHECKS.
If the fuse F1 20A is blown, there is 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 fuse with the correct value replacement.
Table: Terminal Connection of Switch
Open circuit
Short circuit
25C 100C
Approximately 10 k
Table: Thermal Cut-out Test
Temperature of "ON" condition
(closed circuit)
Bellow -20C
Bellow -20 or -35C.
Common terminal to Normally close terminal
Short circuit
Open circuit.
200C
Approximately 1 k
Temperature of "OFF" condition
(open circuit)
Above 145C
Above 170C
9 – 3
AX1100(R)
Indication of ohmmeter (When room
temperature is approx. 20C.)
Closed circuit
Closed circuit