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R1900J
[4] D: HIGH VOLTAGE CAPACITOR (1) AND/OR (2) 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 (1) AND/OR (2) 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
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 (1) AND/OR (2) TEST
1. CARRY OUT 3D CHECKS.
2. Before performing this test, make sure that the second-
ary 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 ohmme-
ter as follows. When the door is open, the meter should
indicate a closed circuit. When the monitor switch actua-
tor 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.
[8] H: WEAK POINT TEST
1. CARRY OUT 3D CHECKS.
2. If the weak point (1) or (2) is blown when the door is opened, check the primary interlock relay RY1, secondary interlock switches (1), (2) and mon-
itor switches (1), (2) according to the "TEST PROCEDURE" for those switches before replacing the blown weak point (1) or (2).
CAUTION: CAUTION: BEFORE REPLACING A BLOWN WEAK POINT (1) OR (2), TEST THE PRIMARY INTERLOCK RELAY RY-1, SECONDARY
INTERLOCK SWITCHES (1), (2), DOOR SENSING SWITCH AND MONITOR SWITCHES (1), (2) FOR PROPER OPERATION.
3. If the weak point is blown, check the magnetron, high voltage capacitor, high voltage rectifier assembly, according to the "TEST PROCEDURE"
before replacing the blown weak point. Then replace the weak point.
4. CARRY OUT 4R CHECKS.
Screw Driver
6 – 3
Latch hook
Monitor switch (2)
Monitor switch (1)
Ohmmeter
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