From your wiring diagram that you posted earlier, the square black thing is
more likely a high voltage diode. If that goes out, the microwave hums, but
doesn't heat. If the diode goes, I'd expect the cap to lose its charge. You
might have to slice off the heat shrink to reveal the diode markings on it.
Dash, triangle, bar, dash. Somewhat like --||-- more or less.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

"Danny D." wrote in message
...
On Mon, 17 Dec 2012 18:07:35 -0500, Stormin Mormon wrote:

The ones I've worked on, the diode is connected to the cap.
Your diode might be going from cap to the case of the unit

Ah, there was something there.
http://www5.picturepush.com/photo/a/...g/11714203.jpg

But it looks more like a rectangular ceramic resistor than a tubular
diode.

I haven't measured it due to the warnings about the charge on the
capacitor.

Today I looked at Lowes but they didn't have any black 22 inch by 13 inch
microwaves. The size seems to be the biggest hurdle.