Troubleshooting Procedures

!WARNING

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.

!CAUTION

•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		Cause	Correction
Microwave oven does not work, no	1.	Open or loose wire harness.	If thermal (magnetron) cutout is
display, fuse is OK.	2.	Open thermal (magnetron) cutout.	defective, check fan motor.
	3.	Open low voltage transformer.	If low voltage transformer is
	4.	Defective PCB assembly.	defective, check PCB assembly.
Microwave oven does not work, no	1.	Open or loose wire harness.	Check adjustment of primary,
display, fuse is blown.	2.	Defective primary latch switch.*	interlock monitor and door
	3.	Defective monitor switch.*	sensing switches.
	4.	Shorted high voltage capacitor.*	Check power relay.
	5.	Shorted high voltage transformer.*

*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	1.	Key input is not in-sequence.	Refer to operation instructions.
key input (touch pad input).	2.	Open or loose connection between	Check connection between key
		key pad and PCB assembly.	pad and PCB assembly.
	3.	Shorted or open key pad.	Replace key pad membrane.
	4.	Defective PCB assembly.	Replace PCB assembly.
Microwave oven timer operational,	1.	Latch switches not aligned.	Adjust latch switches.
but microwave does not oscillate	2.	High voltage circuit loose connection	Check connections to high
(rotate).		(magnetron filament circuit).	voltage circuits (magnetron).
	3.	Defective high voltage components.	Check transformer, capacitor,
	4.	Power relay wiring open or loose.	diode and magnetron fuse.
	5.	Primary latch switch defective.	Check power relay wiring.
	6.	Power relay or PCB assembly	Replace power relay or PCB
		defective.	assembly.
Microwave oven lamp and fan	1.	Primary latch switch misadjusted or	Adjust door and latch switches.
motor activate.		loose.
	2.	Primary latch switch defective.	Replace all latch/door switches.
Microwave oven is programmable,	1.	Secondary interlock open or loose	Adjust door and latch switches.
but timer does not work.		wiring.	Adjust door and latch switches.
	2.	Primary interlock switch misadjusted.	Adjust door and latch switches.
	3.	Secondary interlock switch defective.	Replace all latch/door switches.
Microwave oven output is low;	1.	Decrease in power source voltage.	Home voltage fluctuations.
microwave oven takes a long time	2.	High voltage circuit loose connection	Check/replace magnetron.
to cook food.		(magnetron filament circuit).
	3.	Magnetron aging.	Check/replace magnetron.

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