Maytag MMV5156AAS Microwave won't heat and has hum/buzz.

A failed diode isn't the most common failure, but it happens. And sometimes it's due to bad magnetron or a bad connection.

If the capacitor fails, it almost always shorts, which results in a blown fuse whenever you hit "Start" to run the microwave.

The magnetron on this model should have a 5-year warranty, in case that's relevant. Your owner's manual is here.

We have the service / repair manual for this model and have uploaded it to our site here to help you.

It will give you safety info, step by step help in disassembly, troubleshooting tips, and part numbers.

Here are some links you or someone you know can use for test help, but read their safety warnings first:

http://www.gallawa.com/microtech/diode.html
(if it's not shorted or burned, it's probably okay)

http://www.gallawa.com/microtech/mag_test.html

http://www.gallawa.com/microtech/xformer.html

http://www.gallawa.com/microtech/cap_test.html

There should also be a "mini-manual" (tech sheet) hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting, testing, and locating components.



At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

You can find helpful exploded view diagrams and order parts here.

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