• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php


JTP85WA GE Microwave is humming and heating when off and door closed


Premium Member
Mar 5, 2019
Torrance, CA
Model Number
More than 10 years
My GE microwave is humming when the door is shut. I placed a glass of water in and closed the door. No lights on, turntable not moving, but the water got heated. When door is closed, after some time the microwave shuts off for a little while then turns back on. I'm assuming it was overheating then shutting down and once temp was ok, was resetting. Regular operation works fine otherwise to actually set and heat stuff. Just can't close door when not operating!

I replaced the magnetron about two years ago. I checked door switches and they seem to be ok (saw a video where someone mentioned that could solve the problem). Looked on many other threads in here and looked like most common recommendation was to change the control board. The one for my model runs about $375 on here so wanted to make sure I'm headed the right direction before purchasing. Any other recommendations? Much appreciated!


Appliance Tech - Moderator
Staff member
Jul 11, 2006
Murray, Utah 84107, United States
You're correct, there's a short on the board. When the door is closed the control is bypassing the programming and starting a cook cycle. Here's the part you need:
WB27T10463 Microwave Control

I didn't have your complete model number so I went with the first one on the list: JTP85WA1WW