Microwave Magnetron tube has arced

Michelle,
You may have killed the magnetron but you may not have either. If you can take that cover plate off, you may find that there is grease build up behind it and that needs to be cleaned off. Grease can build up there without you even realizing it and after a while it can catch fire from the heat created by the magnetron. You should never put any empty plate or container in a microwave because the magnetron needs to have something for the waves to hit. Hope this helps.

see this steps and fix it. God bless you
If you see arcing or sparking inside a microwave, turn unit off immediately. Arcing can be caused by having something metal in the oven cavity touching a side, an oven shelf is touching the side of the cavity, an oven shelf support has broken, microwave waveguide, or bad magnetron.
If your microwave has a shelf in it, and you do not use it, keep it out. If one of the shelf supports breaks or comes out, the microwave will arc where the support was. You will have to sand the spot down, paint with appliance paint and re-install support. If the shelf shifts on the support and touches the side it will arc.
Your magnetron waveguide will either come out of the top, or side of the oven cavity. Some will have a stirrer in it(mostly top waveguides) with a panel over, or just a cardboard type cover over it. Over time, the stirrer cover can become warped from the heat which will expose the stirrer's metal shaft which will then cause sparking. These covers and stirrers come in a kit and can be replaced from inside the oven cavity.
Your cover over a side waveguide is coated with a substance on it, and overtime this coating can come off from the heat and moisture in the microwave. These waveguide covers are very easy to replace from inside the oven cavity. Touch up any paint that may have chipped or come off because of the arcing.
If your waveguide cover and/or stirrer are all OK, then the spark is coming from your magnetron. The antenna on your magnetrom has overheated and burned, sending the microwaves out at the wrong angle. If you catch this microwave oven repair early enough, you can usually get by with just replacing the magnetron. If the arcing has caused servere damage inside the waveguide, you will need a new microwave. Waveguides are not replaceable and most you can barely see into them, let alone sand and re-paint. In this case of microwave oven repair, when you remove the magnetron, you will see the burned antenna, or your magnetron will fail the test below.

see the guide for test the magenetron and another component.

see this next steps. God bless you
If you see arcing or sparking inside a microwave, turn unit off immediately. Arcing can be caused by having something metal in the oven cavity touching a side, an oven shelf is touching the side of the cavity, an oven shelf support has broken, microwave waveguide, or bad magnetron.
If your microwave has a shelf in it, and you do not use it, keep it out. If one of the shelf supports breaks or comes out, the microwave will arc where the support was. You will have to sand the spot down, paint with appliance paint and re-install support. If the shelf shifts on the support and touches the side it will arc.
Your magnetron waveguide will either come out of the top, or side of the oven cavity. Some will have a stirrer in it(mostly top waveguides) with a panel over, or just a cardboard type cover over it. Over time, the stirrer cover can become warped from the heat which will expose the stirrer's metal shaft which will then cause sparking. These covers and stirrers come in a kit and can be replaced from inside the oven cavity.
Your cover over a side waveguide is coated with a substance on it, and overtime this coating can come off from the heat and moisture in the microwave. These waveguide covers are very easy to replace from inside the oven cavity. Touch up any paint that may have chipped or come off because of the arcing.
If your waveguide cover and/or stirrer are all OK, then the spark is coming from your magnetron. The antenna on your magnetrom has overheated and burned, sending the microwaves out at the wrong angle. If you catch this microwave oven repair early enough, you can usually get by with just replacing the magnetron. If the arcing has caused servere damage inside the waveguide, you will need a new microwave. Waveguides are not replaceable and most you can barely see into them, let alone sand and re-paint. In this case of microwave oven repair, when you remove the magnetron, you will see the burned antenna, or your magnetron will fail the test below.

see the next steps and follow with common sense: God bless you
Microwave is arcing If you see arcing or sparking inside a microwave, turn unit off immediately. Arcing can be caused by having something metal in the oven cavity touching a side, an oven shelf is touching the side of the cavity, an oven shelf support has broken, microwave waveguide, or bad magnetron.
If your microwave has a shelf in it, and you do not use it, keep it out. If one of the shelf supports breaks or comes out, the microwave will arc where the support was. You will have to sand the spot down, paint with appliance paint and re-install support. If the shelf shifts on the support and touches the side it will arc.
Your magnetron waveguide will either come out of the top, or side of the oven cavity. Some will have a stirrer in it(mostly top waveguides) with a panel over, or just a cardboard type cover over it. Over time, the stirrer cover can become warped from the heat which will expose the stirrer's metal shaft which will then cause sparking. These covers and stirrers come in a kit and can be replaced from inside the oven cavity.
Your cover over a side waveguide is coated with a substance on it, and overtime this coating can come off from the heat and moisture in the microwave. These waveguide covers are very easy to replace from inside the oven cavity. Touch up any paint that may have chipped or come off because of the arcing.
If your waveguide cover and/or stirrer are all OK, then the spark is coming from your magnetron. The antenna on your magnetrom has overheated and burned, sending the microwaves out at the wrong angle. If you catch this microwave oven repair early enough, you can usually get by with just replacing the magnetron. If the arcing has caused servere damage inside the waveguide, you will need a new microwave. Waveguides are not replaceable and most you can barely see into them, let alone sand and re-paint. In this case of microwave oven repair, when you remove the magnetron, you will see the burned antenna, or your magnetron will fail the test bel

There is exposed metal, when magnetron is running it will arc if there is exposed metal in the interior cavity which is more common, I have not seen this inside microwave door, inspect door carefully when you open it to see if there are bare spots. The manufacture use to sell microwave cavity paint to prevent this very problem, if this is not corrected it will short out the magnetron.

The magnetron is arcing in the interior and will eventually burn out. Check the inside for bare metal or food particals, if okay! the magnetron is breaking down and will eventually go.

With all due respect, what are you doing to it?
If you use it with nothing in the cavity, that will kill the magnetron otherwise it will last for years and years.
Very unusual and Bosch is a well respected name.
If there is a probem with the oven, Bosch will replace it so take it up with Bosch.

This is not good, the magnetron is arcing because there is exposed metal. The manufacture provides a special enamel white paint that insulates the interior to prevent this. I would contact GE or appliance repairman and not use the oven until this is dealt with, running the microwave unchecked will eventually burn out the magnetron.

If it is burning and arcing at the antenna, it is probably arcing in the wave guide area. Probably will have to replace unit. I have had some success by removing the antenna, sanding and repainting the burnt areas of the cavity and sanding off any burnt marks on the antenna. Need to look at top of mag to see if also arcing there too.

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 hardware stores, department stores or appliance parts stores.

If your waveguide cover is burned, it will need to be replaced. It provides important protection for the magnetron.

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