flashing, like microwaving a metal object

My microwave also started doing this, and simply cleaning the waveguide cover took care of the problem. In my microwave, the waveguide cover is on the inside of the microwave, high on the side wall. It's about the size of a playing card, made of plastic or fiberboard. I removed mine for cleaning, but that wasn't necessary. Simply keeping the inside of your microwave clean may solve this problem.

"Try to find where the arcing is coming from by viewing th e inside of the oven ""cavity"" while the problem is happening. You can safely run a microwave oven with a container of water inside (something like a margerine container for example). The arcing usually indicates that a component is breaking down and carbonizing, therefore becoming conductive and sparking while the oven is on.

It is common for the ""waveguide cover"" to do this. The problem is caused initially by food debris, etc. becoming stuck in the crevices of the cavity and then becoming conductive. When you locate what is arcing, you will know what component needs to be replaced. Jim"

"microwaves are not my playground but i think you should read the microwave troubleshooting

one question to clarify this a little bit

do you mean inside the chamber or inside the back of the microwave?"

"I just want you to understand the risk involved with tinkering with a microwave, from the microwave troubleshooting:

""Careless troubleshooting of a microwave oven can result in death or worse. Experienced technicians have met their maker as a result of a momentary lapse of judgement while testing an oven with the cover removed. Microwave ovens are without a doubt, the most deadly type of consumer electronic equipment in wide spread use.

Please be very careful if you remove any covers."

I'm suggesting that the user keep his/her hands in their pockets during the analysis phase. Make sure that the power is disconnected and the high voltage cap is discharged before doing any disassembly or replacement! Under those conditions, a microwave oven is completely safe to work on. I mean, after almost 40 years in the business, I'm still here!! JIm

"I removed the waveguide cover from my Sharp Microwave as suggested and found carbonized material on the surface that faces away from the oven cavity. It was somewhat baked on so I cleaned it, first with a wet cloth, and then scoured it with an abrasive sponge.

When I reinstalled the cover and tried using the oven the problem was completely resolved. Thanks for this information."