Microwave got hot and now not powering up

[cjacob]

There is a discussion going on at iFixit, please check https://www.ifixit.com/Answers/View/55644/My+microwave+is+not+heating%2C+but+the+timer+is+working. as well.

[hermit]

I notice there is a plastic encasing on one of the wires going from the transformer to the cap... what is in there?

Diode.  You need about 9 volts to read it.  DMM generally won't work unless you add some voltage.  Analog might do it.

[oldway]

How to repair a microwave oven safely ?

(only electrical safety)

[Gyro]

I notice there is a plastic encasing on one of the wires going from the transformer to the cap... what is in there?

Diode.  You need about 9 volts to read it.  DMM generally won't work unless you add some voltage.  Analog might do it.

NOTE: This is a repair thread from back in 2014.

[hermit]

NOTE: This is a repair thread from back in 2014.

Hmmm...  I didn't note the date but a first/one time poster who registered today bumped the thread to link to another site?  hmmm.....

[IanMacdonald]

If the transformer is overheating, likely reason is that the rectifier diode is s/c.  These are a special type designed for the voltage involved. Of course the transformer insulation might  be damaged if the overheating is severe.

The rectifier, along with the capacitor wired in series, is a voltage doubler. If you're wondering how you achieve a voltage doubler with only one diode, well actuallly you don't. The magnetron acts as the second diode.

Usual warning about some really dangerous voltages in these thngs. Don't forget to dump any residual charge on the cap before handling, with a well-insulated tool.

[hermit]

Don't forget to dump any residual charge on the cap before handling, with a well-insulated tool.

Most modern ones have internal bleed capacitors but don't bet your life on them.