Chosen Solution
Fuse blows if door is opened before end of heating. Can be opened anytime not in heating part of cycle. Update (08/16/2018) Model is JVM3160 Df. How would I find the schematic for this?
Here’s an answer I’ve not seen elsewhere: Over time the door latch wears down such that the timing of the interlock switches gets confused. There are three switches that must activate in the correct order. When the latch is worn, the timing of the two lower switches is disrupted. After trying everything else (and I mean EVERYTHING), I noticed the worn latch and started experimenting, opening and closing the door very slowly and listening for the switches to activate. They must be out of sync, somehow. How can I correct it? Believe it or not, I simply wrapped some duct tape around the tip of the lower black plastic latch. This caused one of the lower switches to activate a fraction of a second sooner . . . before the second switch . . . and the problem was solved.
The door safety interlock switch is bad or the connection terminals at the magnetron capacitor is loose causing arching/intermittent voltage surge. WARNING the capacitor is storing high voltage and is a potential shock hazard. A qualified repair technician is highly suggested to service your microwave oven.
SOLVED: I had the same problem with a 3 year old GE Microwave. It comes down to a design flaw. I changed the capacitor and all three switches and still had the problem. The issue turned out to be the white plastic housing that holds the 3 switches. Over time the hooks from the door latches wear away where they meet the white housing. In my case the top hole wore down faster than the lower hole causing the switches to release at different times when the door is opened which will in turn send a power surge to blow the fuse. Attached a picture of the worn piece. Certainly check the continuity of the switches first. Second I would replace the plastic piece holding the switches. I say do those first because they are the most likely causes and you don’t have to take the microwave down to do it. Lastly, if you still have problems, I would change the capacitor (DANGER - capacitors hold a potentially deadly charge).
I took away the switch in the middle. That switch simply short 120 AC power when door opens. If there still power, it just blow the fuse. It is overkill, because another switch (top one) opens when door is open and cancel 120AC power from outlet. It is double protection (not necessary for my opinion). Timing is the problem and with flimsy plastic supports of all three switches shortening switch can close before power interrupted by top (power) switch. That will blow the fuse. And one can change a dozen of switches and other parts, but will have the same problem. Can try to redesign switch support, adjust switches position making timing reliable, but just eliminating shortening switch is an easy and fast solution. I blew up four fuses in couple weeks, but now microwave works without problems.
I found the schematic and trouble shooting chart folded inside the back of the control panel on my JVM3160DF2WW. Did you find a solution to your fuse blowing problem? Mine is blowing the 20A fuse at first when opened door during cooking. I found the lower left hand bracket for the door hinge was loose (the spot weld broke). I fixed it with a small low profile bolt and a nut with lock washer in a pre-drilled hole behind the door when you remove the door. The door was sagging a bit before the fix but it blew another fuse on startup. I need to check the door switches.
Most homes have circuitry that’s limited to a 3000w per set and you can have multiple sets such as when set runs the ceiling lights other sets run other rooms walls or sections of the house. However just 3,000 watt limit makes it so you can’t run a frigerator the toaster and a heater or a microwave on the same circuit. If that was your case there would be some understanding of why you could be tripping the circuit when you open the door in microwave but I don’t think that’s your case. You should test the microwave on an unoccupied circuit (that is one that has little or nothing plugged into it most likely a garage). If the device were to trip the circuit all by itself that would mean that there is a short within the microwave and the door could be all or part of the trigger. A spot where our concurred should be noticeable you are in fact creating a surge which is what trips the breaker and this should be noticeable if you were to get inside it. Since you have a limited electrical knowledge I would recommend replacing the unit strictly on the grounds that is much safer than having a microwave burn down in your kitchen.
No, but I modified the tip of the lower latch itself by adding some 2 or 3 layers of duct tape. Not the most elegant solution, but it works for quite a while before the tape gets worn and needs to be renewed. A properly trimmed and mounted strip of tin can would be more permanent . . . either applied to the tip of the latch or, preferably, glued to the worn portion of the latch board. Also bought a couple dozen fuses from China. Cheap. If a little too short, just carefully bend in the fuse mounting brackets. The control board slides onto slots (as you know) and doesn’t need to be screwed in. Same with the upper plastic piece over the door. Same with the shield in front of the fuse. As a result - AFTER UNPLUGGING - I can replace a blown fuse in about two minutes without tools. Long term solution? Avoid GE microwaves in the future. Cheap, shoddy and rickety . . . plus replacement parts are exorbitant. Classic modern planned obsolescence. Oh, and don’t use Goof Off to clean tape residue off the control panel. It reacts with and clouds the plastic.
My plastic latch area was worn only about a 1/32 " but that was enough to cause the blown fuses. There were 3 switches and the middle one which crowbars the power and blows the fuses, ends up closing first due to the worn out plastic. I bent and glued a very thin piece of metal ( from an old floppy disk slide cover - PERFECT thickness) over the worn plastic area about 6 months ago I believe…so far still working fine…thanks to all who brought this to my attention, I thought the fuse flowing was a bad diode or capacitor.
Thanks folks for the information on this thread; it has proven most helpful. Our 5-year-old over-the-range GE microwave has been blowing fuses, but I think that your input has helped resolve the problem. I live in a northern Canadian city. Our microwave is mounted on an exterior wall and vents straight to the outside. Yes it gets cold. A couple years ago, when it was really cold outside (below -30C) it blew a fuse when the door opened. Last year, this started to happen more often, when we were only at -20C. Earlier this winter it started happening at -10C. I found this thread and the next time the fuse blew, I took a look at the switches and found that they had some play in where they were positioned. My guess is that the cold weather caused them to shift such that when the door opened they did not open/close in the right order. I shimmed them so that the switches were better fixed in place and would trigger in the required order. So far (and I’m knocking on wood here) even though we are going through a -20C cold patch, the microwave is continuing to operate without blowing a fuse. So thank you for your insight and advice!
I had made the various repairs I described above. My last issue was the hook on the black plastic door latch wearing down and also grooves worn into the white plastic switch holder caused by the black plastic hook. I think it was the lower hook that wore down and I put a piece of wire insulation shrink tubing around the top of the hook. This built up the worn end of the hook and made it wider than the groove in the white plastic switch holder. It worked for a while but I decided to replace both parts anyway. Since replacement, I put some silicon spray lube on the ends of the black plastic hooks and the surface they slide on when you close the door. I just put 1 drop on the end of a Q-tip and wipe the areas every month or two. I probably have done this now for a couple of years and haven’t noticed any wear on the parts I replaced.
If the microwave is blowing fuses or the breaker while opening the door, chances are really good it’s the monitor switch. Which is the middle or second switch. If you remove the plastic “latch board,” the receptacle the door hooks latch into which holds the switches, be certain to reinstall correctly. Because there’s a small plastic hook that must go through the metal structure before the board is slid downward into position. It’s possible to install this without properly seating it, without sliding it downward into position, but if you do the switches will not align properly with the door hooks and it’ll just blow the fuse or breaker again. Also when ordering the monitor switch make sure you order the right one. Because the upper switch has the same KW3 number on it but they’re not the same switch. And they cannot be substituted because the upper is normally open and the monitor switch is normally closed. Lastly, do not open the microwave door while it’s running. Because it arcs the monitor switch internally every time and shortens its life. Let it finish running or hit cancel.
It is one or all of the door switches, the most Likely one is the bottom switch. This can cause the house circuit breaker or the 20A 125V fuse behind the input panel to blow. There are sets on ebay or eparts with all the switches, two Normally Open & one Normally Closed switch for the set. Make sure you unplug the Microwave before replacing them.
Don’t know if you ever found out, but in my GE OTR microwave the schematic was stuffed into the area where the door switches are. I found it because I had the same problem.
