Troubleshooting Procedures; General - Maytag JMV8186AA Series Service Manual

Troubleshooting Procedures

To avoid risk of electrical shock, personal injury, or death, disconnect power to microwave and discharge
capacitors before servicing, unless testing requires power.
• Verify proper grounding before checking for trouble.
• Be careful of the high voltage circuit.
• Discharge the high voltage capacitor.
• When checking the continuity of the switches or of the high voltage transformer, disconnect one lead wire from
these parts and then check continuity with the AC plug removed. To do otherwise may result in a false reading
or damage to your meter.
•
Do not touch any part of the circuit on the printed circuit board, since static electric discharge may damage the
control panel. Always touch yourself to ground while working on this panel to discharge any static charge built
up in your body.
Symptom
Microwave is dead.
Fuse is OK.
No display/no operation.
No display/no operation.
Fuse has blown.
Cannot program
microwave (will not
accept key input).
Oven lamp, fan motor
and timer operational,
but no microwave
oscillation (heat).
Microwave lamp
illuminates and fan
motor engages.
Microwave is
programmable, but timer
is not operational.
Microwave output is low
(food cooks slower)
10
!
WARNING
!
CAUTION
Cause
1. Open or loose wire harness.
2. Open thermal cutout (Magnetron).
3. Open low voltage transformer.
4. Defective PCB assembly.
1. Shorted wire harness.
2. Defective primary latch switch (see Note 1).
3. Defective monitor switch (see Note 1).
4. Shorted high voltage capacitor.
5. Shorted high voltage transformer (see Note 2).
NOTE 1: These switches must be replaced at the same time. Also, check continuity
of power relay contacts. If continuity is indicated, replace power relay.
NOTE 2: When high voltage transformer is replaced, also check diode and
magnetron.
1. Key input sequence incorrect.
2. Open or loose membrane keypad connection.
3. Open or shorted membrane panel.
4. Defective PCB assembly.
1. Latch switches not properly aligned.
2. Magnetron filament circuit open or loose.
NOTE: Large amount of contact resistance
results in lower magnetron filament
voltage, causing the magnetron to lower
output and/or intermittent oscillation.
3. Defective high voltage components
(transformer, capacitor, diode, magnetron
fuse).
4. Power relay wiring open or loose.
5. Defective primary latch switch.
6. Defective power relay or PCB assembly.
1. Primary latch switch wiring loose or incorrectly
adjusted.
2. Primary latch switch defective.
1. Secondary interlock switch wiring open/loose.
2. Primary interlock switch incorrectly aligned.
3. Secondary interlock switch defective.
1. Decrease in power source voltage.
2. Magnetron filament circuit wiring open or loose.
3. Aging of magnetron.
16026440
Correction
Check fan motor when thermal
cutout is defective.
Check PCB assembly when low
voltage transformer is defective.
Check adjustment of primary,
interlock monitor, power relay
and door sensing switch.
Refer to Use and Care Guide
for microwave operation.
Replace membrane panel.
Replace main PCB assembly.
Adjust door and latch switches.
Check high voltage component
according to test procedure and
replace if defective.
Replace main PCB.
Adjust door and latch switches,
replace if defective.
Adjust door and interlock
switches, replace if defective.
Consult electrician and verify
household voltage levels.
Replace magnetron.
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