Sharp R-1500AT, Service Manual

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R1500AT
6 – 3
3. CARRY OUT 4R CHECKS.
NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.
[4] D: HIGH VOLTAGE CAPACITOR (C1) AND/OR (C2) TEST
1. CARRY OUT 3D CHECKS.
2. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and check for short or open between the termi-
nals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity for a short time and should indicate an
open circuit once the capacitor is charged. If the above is not the case, check the capacitor with an ohmmeter to see if it is shorted between either
of the terminals and case. If it is shorted, replace the capacitor.
3. CARRY OUT 4R CHECKS.
[5] E: SECONDARY INTERLOCK SWITCH (SW1) AND/OR (SW2) TEST
1. CARRY OUT 3D CHECKS.
2. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch. The meter should indicate an
open circuit with the door open and a closed circuit with the door closed. If improper operation is indicated, replace the secondary interlock switch.
3. Isolate the switch (SW1) and connect the ohmmeter to the common (COM.) and normally close (NC) terminal of the switch (SW1). The meter
should indicate a close circuit with the door open and an open circuit with the door closed. If improper operation is indicated, replace the switch
(SW1).
4. CARRY OUT 4R CHECKS.
[6] F: PRIMARY INTERLOCK SYSTEM TEST
1. DOOR SENSING SWITCH (SW5)
1. CARRY OUT 3D CHECKS.
2. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch. The meter should indicate an
open circuit with the door open and a closed circuit with the door closed. If improper operation is indicated, replace the door sensing switch.
3. CARRY OUT 4R CHECKS.
2. PRIMARY INTERLOCK RELAY (RY1)
1. CARRY OUT 3D CHECKS.
2. Disconnect two (2) wire leads from the male tab terminals of the Primary Interlock Relay RY1. Check the state of the relay contacts using a ohm-
meter. The relay contacts should be open. If the relay contacts are closed, replace the circuit board entirely or the relay itself.
3. CARRY OUT 4R CHECKS.
[7] G: MONITOR SWITCH (SW3) AND/OR (SW4) TEST
1. CARRY OUT 3D CHECKS.
2. Before performing this test, make sure that the secondary interlock switches SW1, SW2 and the primary interlock relay RY1 are operating prop-
erly, according to the above Switch Test Procedure. Disconnect the wire lead from the monitor switches SW3, SW4 (COM) terminals. Check the
monitor switches SW3, SW4 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 continu-
ity of the monitor circuit.
3. CARRY OUT 4R CHECKS.
Screw Driver
Ohmmeter
Monitor switch (2)
Latch hook
Monitor switch (1)