GE microwave blowing fuse

[roffman]

HI, I have a GE microwave (JES1142SJ 04) where the internal fuse has blown three times. I believe that it's related to the door switches, since it happened the last time when I opened the door.   I suspected this after the 2nd time and adjusted the latch assembly, only to have it happen the final time. I tested continuity on all the switches individually and they all appear to work. I have heard these switches can at first appear to be normal and be faulty. I know there is an order to the activation of the switches too, hence my attempt to adjust the assembly to no avail. One thing maybe I should note, is that I used to hold the button in and close the door and release the button so to not make a lot of noise early in the morning. Any advice and thoughts would be greatly appreciated. Thanks

[johntech]

Part number: 28qbp0499

Part number: 28qbp0497

Test switches while they are installed in the machine. They will develop a dead spot where the door holds them shut. Switches are pretty cheap you could just replace all 3.

[johntech]

you can also inspect the terminals. I sometimes see melted plastic around the terminal on bad switches.

[roffman]

Thanks, I didn't see any issue with the connectors or wires.  I thought the same thing about the switches being inexpensive and two of them are, but the "switch primary and secondary" as it's called is surprisingly quite expensive compared to "switch interlock" and "micro switch substitute(?)" which are around $7 so I'm afraid I'm loathe to spend too much without knowing a part's bad.  I'll reassemble and check the switches more carefully in place.  Thanks

[BrewHobbyTech]

You obviously have at least one bad micro switch. Without replacing the bad one you'll keep having the same problem. It really sucks to keep taking something apart and putting it back together again over and over........

Replace all the switches and be done with it.......or not........just a little advice. 

[roffman]

yeah, I grapple with that.  Part of me thinks it's a good down payment on a replacement, and the other guy on the shoulder says...what a waste to scrap a perfectly functional thing for a switch.  I'll report back.  Thanks for the thoughts

[johntech]

The switches I posted are pretty cheap around $3-$7 each. They are listed as Nla at appliance parts pros and Marcone but are readily available from other suppliers like Servall, Apd, and repair clinic.

[roffman]

Using the m/w model number on those sites, the primary/secondary switch is between ~$54 and ~$76.  Is there an alternative that I'm not seeing perhaps?  Seems like they should are similar and should all be around the same price, but I don't know the internal workings.  Thanks

[roffman]

Actually, I suppose swap out the cheapies, and if that doesn't work, then we've narrowed it down to the more expensive one and not out much $ just time.

[Hiroshi]

If the primary and secondary are not being actuated at the exact moment, the third or "monitor" switch is designed to short and blow the fuse... so it is going to be either the primary or secondary switch for certain, you could purchase ONE of the primary/secondary parts and with an extra couple of fuses and figure out which switch is not working properly by trial and error. The monitor switch is proven to work as it is blowing the fuse!

[Hiroshi]

The cheaper switch is not the right rating, nor is it durable enough to replace the other two, or it would be expensive as well...

[roffman]

I should clarify, I meant 'cheap' as in 'inexpensive' relative to the one switch.  Two of them are under $10 and the one is as noted a lot more.  Although, I am trusting that the appliance parts suppliers have OEM or comparable parts

[Hiroshi]

By cheap, I was also referring to the price, but keep in mind, the manufacturers are well aware that technicians are all about lowering expenses and are on to many of our "tricks."

[BradE]

I carry tons of these 2 switches on my truck. Works on just about every microwave I have worked on. They will work for the NO and NC switches. Any they are super cheap. 495 has the 3/16" terminals and 496 has 1/4"

Part number: 28QBP0495

Part number: 28QBP0496

Edited September 13, 2016 by BradE

[BrewHobbyTech]

52 minutes ago, BradE said:

I carry tons of these 2 switches on my truck. Works on just about every microwave I have worked on.

I don't work on microwave ovens anymore but I agree with you. I used to replace them all the time with whatever I had on the truck. The ratings for most of what I carried were similar or exact to what I was replacing, and I never had a problem. Now they may be making really cheap pieces of crap switches, and they may not last as long, but they will still work. Plus....GE can have some extreme/outrageous prices on their repair parts. Just replace all three with normal prices micro switches and you should be fine.....at least give it a shot. 

[roffman]

I will, thanks.

[roffman]

Success!! I replaced two low-cost switches and the oven is now working.  During removal of one of the switches, one side of the housing came off which allowed me to look closely inside (using a 10X loupe).  The points were in rough shape as though there had been some arcing events.  It still seemed to work, but damage to the points.  I decided to take apart more and the primary (I think) looked better, but there were signs of overheating.  I then opened one of the two remaining (there are actually 4 individual switches) and the points looked pristine.  My thoughts are that I overused the door switch to stop the cooking rather than use the 'stop' button to interrupt or let the timer run out.  Also, as I mentioned, I used to push the button in while keeping the door shut and then pulling the door as to not make a lot of noise, this might also have caused unusual 'stress' on the switches.  Anyway, just a theory.  I plan to minimize the use of the switches to halt the oven operation.  Thanks again for all the expert advice.  Much appreciated!!  Jim R

[BrewHobbyTech]

Cool stuff bro.....that's awesome. Maybe next time we'll have some s'mores and a nice camp fire going.....and maybe a few homebrews or whatever......Cheers bro......

[Rudy215]

Thanks for sharing,informative post.