Microwave worked fine yesterday. This AM, made loud humming noise and smell of burning electronics. What more do I need to know? Can I replace it myself?

Greg Owens, November 2007

The problem is more likely to be with the transformer or its connections than the magnetron. To save cost transformer primary coils are wound with aluminium wire. The connectors on the ends of the primary winding are usually crimped, not soldered. Over time oxidisation takes place, increasing the resistance in the connnection until it overheats and burns out. Sometimes repairable but sometimes not. If its a cheap model - recycle it.

ike, March 2008

Dear Greg, you haven't detailed the make and model but i think i might be able to put you in the right direction. Generaly you DON'T get a smell like you descibe when a magnetron goes, I would be looking to the power input to the magnetron instead of the magnetron itself. Inspect the transformer, the high voltage capacitor and the diode that is connected to it. However, before you start touching these parts, make sure that the voltage in the capacitor has been dissapated by unpluging the oven from the mains outlet and shorting the capacitor terminals down to earth. Please be careful doing this as the voltage held there is enough to kill you, back in 1988 when i first started working with microwaves 8 out of 10 engineers that got the high voltage across their hands were killed.

Darren Chambers, November 2007