Magic Chef Microwave Smokes and Smells like Burned Plastic

[amodoko]

Ok, today my roommate told me that he saw smoke coming from the microwave when it was on. He said it also smelled like burned plastic, so he shut it off immediately. The smoke was coming from the vent where the microwave light is.

Also, our wave guide cover is all charred up and black. I don't know if that is what is burning, or if it is something more serious. I tried to mess with it and do a quick test, so I put a glass of water in the microwave and noticed when I turned the microwave on, after about 15 seconds, it would smell like burned plastic and smoke quite a bit. I also noticed that the glass of water would not heat up. So it is smoking, yet won't heat up any food/liquids now.

What do you think the problem is? It can't just be the wave guide I'm assuming since the microwave will no longer heat food.

P.S. My model is the Magic Chef Microwave. It is model number MCD1311ST

[HayZee518]

it is in fact the waveguide cover. shut the oven off unplug it and move it to a table. remove the metal cover and examine the waveguide cover. its made of mica or clear plastic. food may have splashed on it and started to carbonize the guide. carbon conducts electricity as well as microwaves. replace the cover.

[amodoko]

I guess the waveguide cover would explain the burnt plastic smell and smoke, but it wouldn't fix the fact that the microwave isn't heating up right?

Because it won't heat food now, if I put water in there it won't even heat the water, it is still cold after it's in there.

[HayZee518]

the microwave energy is shorting out through the burnt waveguide cover to ground. because carbon is conductive, try removing the cover and just heat water in the cavity and see if the problem goes away.

[amodoko]

Thanks for the reply bud, I appreciate it. Ok, so I took the waveguide cover out and put in a cold glass of water. I turned the microwave on and after about 18 seconds I had to shut it off because it started smoking again, and smelling like burnt plastic. The odor was too strong. I checked the glass of water, and it was ice cold, it didn't heat up one bit.

So it's smelling like burnt plastic and not heating up food/liquids regardless of the waveguide cover. What should I look into next?

[HayZee518]

with the metal cover off - look at the path the microwaves take from the magnetron cavity. the magnetron is the square looking tube with wires going to the bottom. the waveguide is a highly polished tube may be square or rectanguler. microwaves feed into the tube by a stub length of conductor. microwaves are like radar, only instead of bouncing out and returning [doppler radars emit and the look for a return] the waves just go out of the machine. go to repairclinic dot com and try to find your machine. besides I think they could supply you with more help.

[HayZee518]

look for a high voltage diode in the control section near the front bottom. if this thing opens no heat will be generated.