Troubleshooting Procedures; Troubleshooting Table - Maytag UMV1152CA Manual

Troubleshooting Procedures

To avoid risk of electrical shock, personal injury, or death, disconnect power to microwave oven and discharge the
high-voltage capacitor 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.

Troubleshooting Table

Symptom
Microwave oven does not work, no
display, fuse is OK.
Microwave oven does not work, no
display, fuse is blown.
*NOTES: If any primary, interlock monitor or door sensing switches are defective, replace all at the same time.
If power relay contacts measure continuity, replace also.
If high voltage transformer is replaced, check diode and magnetron also.
Microwave oven does not accept
key input (touch pad input).
Microwave oven timer operational,
but microwave does not oscillate
(rotate).
Microwave oven lamp and fan
motor activate.
Microwave oven is programmable,
but timer does not work.
Microwave oven output is low;
microwave oven takes a long time
to cook food.
10
!
WARNING
!
CAUTION
Cause
1. Open or loose wire harness.
2. Open thermal (magnetron) cutout.
3. Open low voltage transformer.
4. Defective PCB assembly.
1. Open or loose wire harness.
2. Defective primary latch switch.*
3. Defective monitor switch.*
4. Shorted high voltage capacitor.*
5. Shorted high voltage transformer.*
1. Key input is not in-sequence.
2. Open or loose connection between
key pad and PCB assembly.
3. Shorted or open key pad.
4. Defective PCB assembly.
1. Latch switches not aligned.
2. High voltage circuit loose connection
(magnetron filament circuit).
3. Defective high voltage components.
4. Power relay wiring open or loose.
5. Primary latch switch defective.
6. Power relay or PCB assembly
defective.
1. Primary latch switch misadjusted or
loose.
2. Primary latch switch defective.
1. Secondary interlock open or loose
wiring.
2. Primary interlock switch misadjusted.
3. Secondary interlock switch defective.
1. Decrease in power source voltage.
2. High voltage circuit loose connection
(magnetron filament circuit).
3. Magnetron aging.
16027303
Correction
If thermal (magnetron) cutout is
defective, check fan motor.
If low voltage transformer is
defective, check PCB assembly.
Check adjustment of primary,
interlock monitor and door
sensing switches.
Check power relay.
Refer to operation instructions.
Check connection between key
pad and PCB assembly.
Replace key pad membrane.
Replace PCB assembly.
Adjust latch switches.
Check connections to high
voltage circuits (magnetron).
Check transformer, capacitor,
diode and magnetron fuse.
Check power relay wiring.
Replace power relay or PCB
assembly.
Adjust door and latch switches.
Replace all latch/door switches.
Adjust door and latch switches.
Adjust door and latch switches.
Replace all latch/door switches.
Home voltage fluctuations.
Check/replace magnetron.
Check/replace magnetron.
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