I have a GE JKP69BW1BB built-in combination Microwave & Oven unit. Recently while doing a lot of cooking with both the microwave and oven the microwave audibly "popped" and quit working. The pop was accompanied by a bright flash. Both the oven and microwave were very hot at the time. My appliance repairman doesn't handle microwaves so I took a look at it and found the fuse was blown. Replacing the fuse and starting the microwave resulted in a split second of cooking hum and then the fuse blew. Research showed the problem was most likely the door switches, the transformer or the HV capacitor. I tested the capacitor first and it showed 1.7 ohms resistance. The original GE part was not available, but I was able to find a very close replacement. I installed the replacement capacitor and tried the microwave again. The microwave now runs without blowing the fuse, but it doesn't sound right. It runs very quiet even on full power. I heated 2 cups of water for 2 minutes and it did get hot. In the past there was an audible hum for the cook cycle and also what I always thought was a "fan" running. Now the cook cycle is very quiet and there is no "fan" noise. There was also an electrical heat smell coming from the microwave. I tested the fan by bypassing the thermal cutout and it ran continuously. And this fan noise is not the sound I normally associated with the microwave during cooking. It appears to only come on when the microwave or oven heats up enough to trip the thermal cutout. So, did something else fail at the same time as the HV capacitor? And what makes the fan-like noise during cooking that isn't now? Thanks for any help you can provide.
The rectifier diode could indeed be bad. But first I would want to know what value (in uF) the old one was and what is the value of the new one? If they're too far off, the difference in the capacitive reactance could throw off the "tuning" of the circuit. The uF value of the capacitor is optimized in relation to the other components used in the system. Of course, you'd also want to be sure your new cap is at or slightly above the working voltage rating of the old one, too.
That cap sounds good, both capacitance and working voltage (WV).
The diode is the next suspect. Generic replacements are usually fine as long as they fit.
×
You can disconnect the HV wire (red) at the magnatron (isolate it so there can be no sparking). Activate the oven and see if it still blows the breaker. If not, the magnatron is defective and should be replaced. They are available online for around $60. If the breaker "blows" as a result of the test, it's time for a new microwave oven! (You know you want one!)
Where is my answer?
If the capacitor was shorted, I bet the diode that is connected to one side of the capacitor is No good as well.
1,687 views
Usually answered in minutes!
Thanks for the quick responses.
The existing capacitor was 0.95uF and 2000watts. The replacement was 0.92uF and 2100watts. This was the closest in rating and case dimensions that I could find locally (Alaska). Online I've found 0.95uF/2100watt capacitors with similar case dimensions. I could always order one of these.
I wondered about the diode. I'll see about testing it and looking locally for a replacement.
If you have other ideas please post. I'll post what I find with the diode.
Thanks:)
Cant bug diode my voltmeter wont detect the high forward voltage, but the 0.92 uF 2100 volt cap seems shorted and reads 9 ohms.
Have some spare mw guts in the garage I might have the used parts.
Sharp 1100 watt oven, microwave only.
hello, good afternoon, I need an answer, I took to pieces a microwave samsung mod. smw 8711 w made in brazil with 1500 watts and I am going to get on a row of seats, which is going to happen with me the magnatron is tied
The diagram on the VP235A-OF switch in my GE microwave oven (JVM1339) indicates it is normally closed but I found during debugging a problem with my microwave that it is normally open. I can't find a schematic on-line. Does anyone know what it's unclosed state is supposed to be?
Everything works fine except that it quit warming or cooking...even bread is still
after 10 sec run...could it be the fuse?
Microwave was heating, then made a louder than usual fan noise for a few seconds, and then shut off with no sign of life in the unit.
×