The power on my microwave JVM1340WW002 started to go down after few seconds into operation (~5 sec not right away) and then shut down completely. Found that fuse was blown. After replacing the fuse it would shut down as soon as it would start, blowing the fuse again. The High power Capacitor and rectifier show no visible sign of damage. Checked door switch and thermal sensors (two of them - both fine: one is normally open). It leaves either HV Capacitor/Diode, Transformer or Magnetron (still under warranty). I would be inclined to suspect the Capacitor, but the fact that microwave was able to start and died down in few seconds raises doubts. My understanding is that HV cap is there to provide the boost on start up only. Please help.
Generally speaking, if the high voltage capacitor is shorted, the fuse will blow as soon as you hit the START pad. When the HV cap fails, I've never seen one do anything but short. If it's a few seconds or so into cooking, it's usually the high-voltage transformer. There may or may not be a burning smell. The cooling fan often will dissipate the smell. What can happen to the transformer is an expansion of the windings to the point where a couple of hot spots eventually make bare spots which touch, then the short causes the fuse to blow. When it cools, they aren't shorting anymore. It's possible it's the mag or something else, but not too likely. You can (carefully!) disconnect the primary leads from the HV transformer then run the oven, making sure the wires are free and clear. If the fuse blows, the problem is in the low-voltage side. If it doesn't the trouble is in the HV side. If you broke a seal (tamper tag) or left any other evidence that you were inside the microwave, your warranty will be voided. Some parts may be covered, but the labor warranty usually expires sooner. Be careful.
If it blows the fuse as soon as you hit the START button, it's almost certainly a shorted high-voltage capacitor.
If it blows a few seconds after you hit the START button, it's probably the high-voltage transformer. You'll possibly also smell a faint electrical burning smell from the rear vent after you shut if off.
Microwave can be very dangerous so it is best to have it looked by a professional
Would appreciate a solved rating for expert advise.
1,025 views
Usually answered in minutes!
I appreciate the initial respons on below problem description, but need further clarification. Though the fuse does blow as soon as I hit the "Start" keypad, pointing to faulty HV Cap, the way the microwave died is a suspect. As I described, it started fine and died down after few seconds - you could hear as the power just start going down. Can HV capacitor die in such a way?
Your answer provided high level of experise and I was ready to buy the HV Capacitor, when the Repairclinic.com answer came in and it is as follows (see my comments back to them when they first pointed to a door switch):
Repairclinic.com (they first blaimed the door switch):
This microwave has 3 door switches, 2 secondary and 1 monitor. From that description it sounds like a bad high voltage component like the magnetron or transformer.
Hate to be a pest, but could the the magnetron or transformer be faulty? Or these guys at Repairclinic.com just paying me a lip service - just like the first time when they said its a door switch? Here is what I wrote to them before they came back with "magnetron or transformer" explanation:
My foolowup with Repairclinic.com: I appreciate the initial response on below problem description, but need further clarification. As I decribed, I checked the door switches - all fine. I was hoping for more meaningfull answer. Though I suspect the HV Cap, the manner in which the micrawave died may or may not be consistant with Ccap failure. The microwave initially started fine but started to die after few seconds (3-5 sec)- you could hear as the power just start go down. After the fuse replacement it would blow it as soon as I hit the "Start" keypad. My question: Can the initial non-instanteneous failure be attributed to HV capacitor problem or is it something else (transformer or magnetron or triac)?
My GE JVM1650 will run for a few seconds and then shut off. After resetting the clock and date, sometimes it works fine and sometimes it will shut own again. I have unplugged the microwave and plugged back in a few minutes later. Sometimes the microwave will run properly and sometimes it shutts down after a few seconds.
×