Microwave door switch question

[ken]

My sister's 1984 GE OTR microwave, Model JVM64003, quit operating a while back and I never got around to checking it out. Clock is still lit and keeping time. Still able to enter cook time and when start is pushed light inside comes on, time counts down but no magnetron action. After viewing a couple vids on Youtube concerning this problem I suspect the door switch that supplies power to the magnetron is bad.

My question has to do with the switch. After looking online Im getting the impression there are generic replacements. The part # of the original is WB24X5167. Long ago discontinued. There are a few NOS on ebay for $90-$100. Main difference I see is 2 and 3 terminal and also normally open and normally closed. I believe the ones with three terminals have the third so they can replace a normally open or normally closed original.

If I find the switch is the problem does anyone here know if any switch with the same electrical specs and dimensions would be an acceptable replacement or is an exact replacement necessary?

Here's a vid showing the same problem:

 

[combo52]

MWO Door Switches

Bad door SWs are a common problem on most MWOs,

 

There are at least three DSs on nearly all MWOs, some have 4.

 

It is common to have one of the two that carry power fail, wiring is too small and the DSs are also too small and cheap.

 

Good news it is an easy repair and the individual SWs are only a few bucks appease.

 

Usually one of the DS terminals will look a little overheated, you will need to replace the SW and the wire terminal, it is best to splice in a few inches of heavier wire along with a new wire terminal for a lasting repair.

 

John L.

 

[turbokinetic]

Hi Ken. In general, if the switch fits and works mechanically, that is going to be the hardest part to get right with a generic switch.

The 3-terminal switches are often called "form C" contacts and can be used to replace a normally-open or a normally-closed switch.  Sometimes, both the NC and NO are used at the same time. For instance, one side for a door light and the other for power to the heating system.

Microwaves have multiple door switches which have to make and break in a specific sequence.  One switch will turn off power to the heating system as the door begins to open.  Then, after the first switch has turned off power, a second switch will "bridge" the power input to the power transformer. This is often called an interlock monitoring switch. Its sole purpose is to short-circuit the power to the transformer and blow the fuse, in the event that the door switch does not turn off the power to the magnetron system. It's a safety device to prevent people getting burns on their hands from reaching in front of the magnetron while it is still on, if the door switches are not working.

If the switch mechanism isn't adjusted correctly, or is worn / damaged it is possible for these switches to get out of sequence. Be sure that it is working correctly before powering it up. Sometimes it will destroy the switches instantly if the interlock monitor switch shorts the system with power on. The fuse will always blow, but the switches often also are destroyed.