Hi, my Whirlpool microwave AT311 had a bad timer knob which had bad contacts intermittently. As a result it wouldn't power on at all when the contact wasn't right. When I jiggled the button a bit, power would normally return. For setting the timer I just used the start button which ads 10 sec every time you push it. It was a work-around which held up. Now lately it wasn't intermittently anymore that the timer knob made the microwave fail, but constantly. So it was completly dead. As the fuses, door contacts and lock all were OK, I desoldered the timer knob from the board (which resulted in the machine being dead instead of working and I don't have a replacement). I have some general electronics spare parts laying about so maybe something can be used, but my knowledge doesn't reach far enough to know what to use. The timer knob was conected by three pinhole contact points. How can I get the microwave to power on again? In all, I find it very weird that a faulty timer knob can be enough to pull all power away from the control board. Any ideas?
It is the power switch , you remove it, and you get no power.
Electronics are sensitive, and if you try bypassing the switch, you probably burn up the board.
Find an appliance parts sales place, and buy a new board, with switch assembly.
Then it's just a plug, and go repair.