My GE microwave is starting to arc, You can see the arcs on the plate (I believe it is the wave guide cover) on the right side interior. Burn marks are evident on teh plate. Is it the waveguide cover or the magnatron going out. It doesn't smell when it arcs and no fuses are popped.

You may be able to get another mica sheet from a different brand or model and cut it to suit. They are called wave guide covers. I wouldn't recommend using silicone. These usually burn through if food has splattered on to it and eventually, it will burn a hole through the mica. Its common for them to arc around the place where they have burnt.

Sounds like it is arcing there. Is there a plastic or Mica cover there?? If so that is the wave guide cover and it will need to be replaced and any and all carbon burn marks totally cleaned out to be able to save the machine. You can remove the burnt cover and run the unit with a container of water in it to see if it still arcs. If it does more cleaning will be needed if not, replace the covers with new ones and you should be good.

Typically most arcing in a microwave is caused by food splatter. A microwave cannot tell the difference between what is on a plate or on the wall or ceiling. Every food particle in a microwave will continue to cook until it turns to carbon and will attract the microwave energy and focus it to that spot and the unit will arc. Thorough cleaning of the entire microwave cooking cavity and removal of any burn or soot mark will commonly stop the arcing. If your microwave has a painted cavity, you can even use some very fine sand paper to remove any burn mark. Always cover what you are warming and really keep the inside of the microwave clean. If your wave guide cover is made out of the Mica board, and If it has gotten wet from cleaning or from splatter, it must be replaced. You can either order a new one or order a sheet of the mica board and cut out a new one yourself. If the microwave is arcing in the waveguide, generally the unit will need to be replaced. One quick test to see if the unit will work is to remove the bad cover and place a small container of water in the unit, run the machine of a minute or so and see if it still arcs. If it does, the arcing is in the waveguide area, if not it may have just been a problem with the cover. You can run the unit without the waveguide cover in place, it is only there to prevent splatter from getting into the waveguide, so removing it to test the unit is ok. If the area inside the wave guide shows signs of soot and arcing. You can try to wipe that out with some alcohol or lacquer thinner and then try it again. Good Luck.

Remove waveguide cover and clean thoroughly.

That metal plate is probably the waveguide cover. It is made of Mica and must be kept clean otherwise it will arc and burn. The reason it arcs more when solid/frozen food are placed in the oven is because solid/frozen foods do not absorb as much energy as wet foods.
Replace it if it is burnt.

The plastic is a wave guide cover. It will need replaced to keep splatter from getting in there. The arcing has left carbon deposits that must be cleaned and any bare metal repainted with microwave paint. It might be fixable but that depends on the extent of the damage. Eric

Hi,

It looks like there's lightning (arcing) inside my microwave When you see arcing inside your microwave, it's because of food or liquid left in the cavity or on the wave-guide cover:

• If the wave guide has any burn spots, replace it and clean the unit well.
  
  
• If the cavity has any burn spots, spot-sand it smooth and touch it up with microwave interior paint.
  
  

Note… If there are any burn holes in the cavity, don't use the unit-seek help from a qualified appliance repair technician.

Thanks for contacting Fixya

Your problem is a common one. When you see arcing inside your microwave, it's because of food or liquid left in the cavity or on the wave-guide cover:

• If the wave guide has any burn spots, replace it and clean the unit well.
  
  
• If the cavity has any burn spots, spot-sand it smooth and touch it up with microwave interior paint.
  

Note… If there are any burn holes in the cavity, don't use the unit-seek help from a qualified appliance repair technician.

Q - When there is small amounts of food in the oven, arcing occurs right behind the plate where the wave guide comes into the oven. Sometimes it works well and sometimes you can't even put in a bag of popcorn. Any ideas? Could food have 'dripped' in here and be causing a microwave short?
 
A - Yes! Food splatter or drips can continue to cook and will carbon over creating sparks/arcs from the wave guide cover. Usually can clean up the food on and under the wave guide cover, if the oven liner has been damaged we usually lightly sand and touch up those marks with touch paint. Do not let it go for too long as damage to the magnetron end is possible as well :(   If the wave guide cover has been damaged, replace it!

Quite often this is due to grease or food particles stuck to the inside of the oven or stuck on or behind the waveguide cover.

The waveguide cover is usually about the size of a playing card and often held in place by a plastic rivet.

In some models it is the plastic ceiling.

It can be fragile, and the metal edges of the oven behind it can be sharp, so be careful!

The cover and the metal behind it should be cleaned with a mild, non-ammonia cleaner.

If the cavity metal of the oven is chipped or charred, it will have to be sanded smooth and clean and dried thoroughly.

Then you can apply some high-temperature appliance paint, available from places like Wal-Mart, Lowe's or Builder's Square.

If your waveguide cover is burned, it will need to be replaced.

If you need more specific help, please reply back with your brand and full model number.

We're happy to help and we appreciate your thoughtful rating of our answer.

William E. Miller, AS-EET
[email protected]
http://www.microwavedisplay.com