Follow up to: Unit shuts off (JVM1340WW002) and blows fuses

Rings??? Do you mean the thermal protectors?? Some are normally open, others are called a fan switch, and only close if the unit gets too hot and then it closes to turn on the fan to cool the unit. Need to know which one you are checking. A limit to shut down the unit as protection, or a fan switch to turn on the fan to cool the unit down.

All microwaves are 30 inches wide.

Katherine, there is an internal fuse on microwaves. First, make sure you un-plug the microwave and then you will need to take the cover off of the unit. You will find screws on the back and sometimes the sides that hold the cover on. Once you have the cover off, look for where the power cord goes into the machine. There will be three wires coming out of the power cord, one black, one white, and one green. Follow the black wire and it will usually take you right to the fuse in a holder, or to a circuit where the fuse will be located. You will need to look at the end of the fuse to see what amperage fuse you will need. Most microwaves use either a 15 or a 20 amp fuse. Make sure you replace with the identical size fuse. If it blows again right away, that means you have further problems and should have it looked at by a regular repairman. Hope this helps!

This is either a sticking relay, in which case you'd need circuit board repair, or a sticking door switch or defective door switch mount.

See my help file on door switches here.

If you need further help, feel free to contact me or follow up here with your full model number.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

You jerks !

I ask for specific help and your site is just a way to get names to offer plans. What a crock.

It appears like the high voltage capacitor is shorted or the diode connected to the capacitor. You might want to check the monitoring switch as well if the capacitor and diode are good.
Click here for more info on how to work around these high voltage devices.
Let me know if you need further assistance.

The fuse is internal and you will have to remove the cover to be able to access it. Unplug the unit. Once you remove the cover, follow where the power cord goes into the unit. The fuse should be in that area. Replace the fuse with the EXACT value of that of the original one.

If the fuse blows again when you put the cover back on and turn it on, then this indicates that you have a problem in the power supply or with the magenetron.

Please let me know if I can be of further assistance to you.

Good luck!
- Jim

http://www.repairclinic.com/0047_6.asp
Check this out..

> My question: Could they be right about the transformer and magnetron? It certainly could be the transformer or the magnetron, but I really don't think so. Not that I'm recommending that an inexperienced or unqualified person should do this - and bearing in mind that any person who would do so must assume ALL liability for injury or damage - here's how I (on a VERY careful day *grin*) would find out: - I would disconnect the oven's power cord from the wall - I would remove the outer cover - I would discharge the high voltage capacitor - I would look again to be sure the plug is out of the wall - I would make a careful note of and/or mark the exact connections of the wires going to the HV capacitor - I would be very careful in case the connectors have positive locks and not yank on them before I push in the locks - I would disconnect the wires from HV capacitor - I would set my meter to a medium or high resistance scale and touch one probe to each capacitor terminal and from each terminal to the case of the capacitor - If either reading held steady at less than infinity I would replace the capacitor, reconnect the wires, reassemble and test - If neither reading held steady at less than infinity I would reconnect the wires - I would then make a careful note and/or mark the exact locations of the wires attached to the transformer - I would then disconnect just the lead which goes from the secondary of the transformer to the capacitor - I would then remove the other end of that lead wire - I would then insert a new fuse then plug the microwave into the wall and test it - If the fuse blew, I would know it's not the capacitor or the magnetron and I would troubleshoot further - If the fuse did not blow, I would know it's the magnetron or the capacitor (but I just measured the capacitor and it's not shorted!! *grin*) - I would unplug it again from the wall - I would install a new capacitor, hook it all back up, install a new fuse, reconnect the wires, and test it again Sorry to be so stiff about my reply, but I do not want to advise or suggest that an untrained or inexperienced should troubleshoot or work on a microwave oven. The voltages can be instantly lethal. Good luck and be safe!!!

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.