Terminal connector to the door switch overheated & fuse blown
No power to microwave. Opened up and found the 18amp fuse blown...I replaced it and power was restored. Also found overheated/burned/melted wire connector on one of the door switches ( the one that controls the light and rotating plate). I cleaned and reconnected the terminal and it overheated again when I turned the unit on. What is causing this terminal to overheat? PANASONIC MICROWAVE 1300W NN-5943BF
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Inspect the door switches and the wiring in the light bulb circuit. If the problem is a door switch, it will probably be visibly broken, or there will be burn marks on it. It's also possible that the door switch bracket is bent or broken and allows the terminals to short to the oven frame. Check the lamp socket - if it is cracked or burned, it should be replaced.
Also look for signs of arcing or burn marks on the controller board, especially near the relays (usually black plastic boxes about 1" x 1' x 3/4' mounted near the wire terminals or wire harness connector).
As a general note, it is rare for a fuse to fail by itself. If you find a blown fuse, look for a cause before replacing it. This may prevent wasting another fuse.
The original problem, was probably caused by a bad door switch along with the fuse, now there is a good chance the control panel is damaged, you will need a professional to assess if the item is worth fixing.
Without other information, sometimes the fuse blows due to interlock switches. There are usually three or four switches that are activated by the microwave door. If any of the switches are not working properly, the microwave will not turn on.
the problem your are experiencing with your microwave oven is a failed interlock switch. Be careful when closing your microwave door. Slamming the door too hard is one of the main reasons that the interlock switch is damaged.
Slamming the microwave door shut can easily blow the microwave fuse, but they can also blow due to problems with the interlock switches. A microwave oven will not function until the fuse is replaced.
Instruction on how to replace fuse on microwave.
1. Unplug the microwave from the electrical outlet to prevent electrocution. Place the microwave in a well-lit area to be able to locate the fuse.
2. Use a screwdriver to remove the outer cabinet of the microwave, and follow the power cord to the fuse. The fuse is located 2 to 3 inches within the microwave and is attached to the power board.
3. Observe the fuse to determine if it is blown. Blown glass fuses will produce burn marks on nearby surfaces, or the internal fuse wire will be black and melted, while ceramic fuses show no outward appearance of being blown.
4. Determine if a ceramic fuse is blown by testing it with an ohmmeter. If the ohmmeter reads zero ohms, your fuse is not blown. Other readings on the ohmmeter show that your fuse is blown.
5. Replace the blown fuse by popping it out of its holder, and snapping a new fuse in its place. Tighten the fuse clips by squeezing them together with your fingers.
6. Replace the outer cabinet of the microwave, and plug the microwave back into the electrical outlet. Test the microwave to see if it's working properly.
Sounds like a short in the microwave circuit. One or more of the following four components has failed -
Transformer Magnetron Diode Capacitor
Repair is not for the amateur, unless you know how to take things apart, and put them back together EXACTLY as the were found.
Parts are available on the Net, and you can get the P/N's off the old components to identify suppliers of the new ones.
Don't try and measure resistance of the diode. It's impedance is far too high to get a good reading. They're cheap anyway. Always replace the capacitor, they're cheap too. No way to test the magnetron, and the transformer is not easy to test either.
I've had this problem twice with our microwave. The hint to where the problem lies is that the breaker blows when you open the door at times. Inside the microwave are three microswitches; primary and secondary interlock micro switches and an Interlock Monitor switch. The switches are supposed to shut down the microwave if it is running and the door is opened. But, I've found the upper primary switch can stick internal at times and when the door is opened the stuck switch will, because of the way it is wired as a safety switch, cause either the fuse or possibly the main circuit breaker for the oven to pop. The reason the stuck switch blows the breaker or fuse is when the door is opened the interlock switch will cause the neutral wire from the AC power to be applied to the Upper Primary Interlock switch which normally should be open when the door is opened, but if the switch is intermittent or the contacts weld themselves shut the neutral line is connected direct to the "hot" side of the power line through the fuse and thermostat. The first time my microwave failed the switch had melted the contacts together inside the switch and the second time the switch became intermittent and would blow the breaker to the over ever so often. I suspected the switch the second time this happened and utilizing an ohm meter I checked the switch several times by opening and closing the door and once in a while it would remain closed instead of opening when the door was opened. Of course while trouble shooting the power cord to the microwave must be disconnected and use all safety precautions when working around the high voltage areas inside the microwave. I wrote Jenn-Air about the bad switch and the way it is wired into the circuit, but never received any acknowledgement. I suspect these microswitches are under rated for the amount of current that passes through the switch, thus they overheat and eventually arc the contacts together. I hope this helps explain the intermittent problem and could explain many of the intermittent blown fuse problems I see in these internet help sessions
sound like the door monitor switched has blown or shifted out of position if the switches dont operate in tandem when door is opened or closed it will blow the 10 amp fuse and kill the display they will need to be checked by engineer if it is monitor switch they are not expensive to replace.
You say when you "power on" the fuse blows?
If that means when you hit the START button to cook, then you probably have a shorted high-voltage capacitor.
If you mean it blows when you plug it in, you probably have a shorted door switch.
Your microwave may also have a wiring diagram pasted on the inside of the outer wrapper or in an envelope. That will help in your tests.
Agrivated, looks like the fuse 18amp is in the back on top. You will have to remove the shell off the microwave to get at it. This one operates with a inverter..you have some high voltage there. Make sure it's unplugged. While you have it apart, check the primary switch, top one on door latch. If the monitor switch finds this closed when the door is opened it will blow that fuse. You also have a cavity thermal cut out that will shut the oven down. Catriver...post back.