Bright flashs andloud popping noise inside. behind metal cover,

Microwaves use a magnetron to generate microwave energy and direct it a rotating blade wheel to spread them around the inside of the oven. If there is any metal in the area to be heated, or any of the blades are bent, even a bit, the microwave energy can be reflected back up to the magnetron area. In this area there is now too much power and it sparks away, so it does not heat the item in the oven.
Because it is sparking it is now a safety hazard the sparks may melt and set fire to plastic parts in it. This is serious it could burn your house down. Bin this microwave and cut the cable off it to make sure no one else ever uses it.

The magnetron may be arcing, get warm soapy water and remove all food particals from inside of microwave oven until spotless, and check the hood for bare metal.

If yours has a metal rack, it may be arcing at the rack holders.

If so, you will need to remove the rack and all the rack holders.

Any grease or carbon arcs will have to be cleaned thoroughly, and if the metal is charred or damaged, you will need to apply some high-temperature appliance paint, available from places like Wal-Mart or Lowe's.

Then replace all of the rack supports, not just the one that arced.

Another common cause of such noise and flash is 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.

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

Sometimes it is a circular piece in the ceiling of the oven.

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.

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

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

You can find links to helpful exploded view diagrams and part ordering help here.

I'd recommend that your bookmark this link to your favorites.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

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

It may also be in the area of the turntable support, coupler, or motor.

The waveguide cover (also called a spatter shield) is usually about the size of a playing card and often held in place by a plastic rivet.

In some models it is a larger stirrer cover type made of thicker plastic in the ceiling of the oven.

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. It provides important protection for the magnetron.

Please write back with your brand and model number if you need further help.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

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.

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. It provides important protection for the magnetron.

You can find helpful exploded view diagrams and order parts by entering your full model number here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

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.

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. It provides important protection for the magnetron.

We have the service manuals for this model and have uploaded them to our site here and here to help you. You will need the free Adobe Reader to view or print them.

The best place to order Sharp parts is Tritronics.

Please write back if you need further help.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

William E. Miller
[email protected]
http://www.microwavedisplay.com

You don't say which make/model microwave you have, but on every model I have ever seen the thing that sits behind the plastic cover is the magnetron - the bit that actually generates the microwaves.

Unless the microwave was a fairly top-end model, you might well be cheaper to just buy a new one.

Hope this helps,

Matt

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.

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.

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.

You can order Sharp parts from Tritronics at http://www.wehaveparts.com

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

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.

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.

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

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

You can usually find helpful exploded view diagrams and order parts by entering your full model number here: http://tinyurl.com/gv383

If not, please reply back with your brand and model.

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

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 cases, it is a stirrer cover covering the top (ceiling) of the oven.

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.

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

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

You can usually find helpful exploded view diagrams and order parts by entering your full model number here: http://tinyurl.com/gv383

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