GE PEM31SM1SS Microwave hums with a loud noise & heats

Hi @jsmith2020 ,

Please verify the model number as you may have missed a digit?

There are several GE PEM31SM?SS models so I just wanted to make sure that you got the correct part in case there is a difference.

Usually the problem you describe is due to a faulty or loose door interlock switch or actuating lever. There are 3 switches in all that need to be checked. Not sure with your model but I think two are normally released (or open) and one is operated (or closed) when the door is open but I may have it around the wrong way

Click on your particular model listed in the link above and then find parts 20, 21 & 22 to find the location of the switches.

Be safety aware when working inside a microwave oven.

The HV capacitor can store >6000V DC for months even if it has been disconnected from the power for this amount of time. This voltage is enough to cause a serious injury or worse if you come into contact with it. The HV capacitor needs to be discharged correctly as soon as it can be accessed after removing the cover and before starting any other work inside the oven.

YouTube videos show using an insulated set of pliers or a screwdriver to short out the capacitor but I’ve witnessed the results when this was done incorrectly or the wrong tool was used - not pretty.

I prefer the safer method of constructing a 10 MOhm 10W resistor in a lead with alligator clips at each end and placing that between the +ve terminal of the HV capacitor and the metal chassis of the oven to discharge the capacitor. It only takes about 5 minutes to discharge and then you can short out the capacitor terminals to totally ensure that it has been completely discharged.