Oven made loud pop. Now does not heat and is loud. Light goes on, turntable turns. No heating

Had the same problem. It was the high voltage rectifier. Bought replacement part at Sears online for about $16 (including shipping) and replaced myself. Not too difficult, but you need to be VERY CAREFUL to discharge the capaciter. You can even leave it mounted, while fixing it. Just remove upper plastic vent covering, which exposes the mounting screw for the control panel. Unscrew and slide the panel up to dismount. You will need to disconnect all the wire attachements to the control panel. I took a digital photograph to ensure I could reconnect exactly as it was originally arranged. The part is attached to the capacitor in the back of the unit - MAKE SURE THE CAPACITOR IS DISCHARGED FIRST.

A couple notes:

• I had read other postings saying that other parts would probably need to be replaced, as their shorting likely caused the failure of this part. However, I traced the shorting to excess moisture - my wife was boiling a lot of pasta on the stove for an event. Once dried out, the short was gone.
• The replacement piece is shaped a little differently and can obscure the internal fan. This can cause the unit to overheat and the circuit breaker to fail, which I found out the hard way (a much more difficult--yet still unexpensive--repair). I used some electrical tape to make sure it stayed out of the way.