I heard a popping sound when I turned on the oven, after which, it stopped heating food. When I press START, the light and fan turn on, and the carrousel turns, but no heat. A visual check of the components did not reveal anything out of the ordinary. I checked the capacitor--it seems fine. I put 50V across its disconnected terminals, and it holds the charge (slowly leaking it through the built-in bleeding resistor). I checked the diode--it passes current in one direction and not the other. I checked the transformer impedance--less than 1 ohm at the input, less than 1 ohm at the output, open from any input and output to the body, except about 80 ohms from the third (red) output to the body. I checked the magnetron--about 1 ohm across its terminals, open from any terminal to the body. I checked the two thermal switches--both are less than 1 ohm across their terminals.

Any ideas what could be the problem?

Thanks in advance.
appusr