Top 20 Panasonic NN-H275 Microwave Oven Questions & Answers

open it and check screws. anything that vibrates will sooner or later loosen internal screws. maybe put a locking ring on it if u find it ManualsLib Makes it easy to find manuals online serach here for service manual .

Remove fan and check for loose debris or screw that is hitting the fan.

Main board is faulty. If you wish to get some details; check the site linked here. Pull up older posts. http://electro-medical.blogspot.com/

I can think of several problems with that 1. Defective lights 2. Defective control board 3. Defective control panel, you just have to check one thing at a time.

Pc board faulty

try a company called e spares on the internet they do most parts or can find them

kindly check door lever

We see and repair this a lot. The problem is on the controller assembly.This light failure often occurs when a bulb goes out and the filament shorts, or when the bulbs are removed or installed without first unplugging the oven from the power line. Either can cause such a failure on the controller. The lights can can be inoperable or stuck on or stuck in "night light" mode. Sometimes this will similarly affect the fan operation or inside light, too. You can find a video here that shows you how to remove the grille & controller in about 5 minutes.

behind the control panel,while your checking the h.v. cap check the h.v. diode for a shorted condition as this will also blow the 20 amp fuse too

If there is spark please do not switch on unless you have confirmed the fault. It is possible that the Magnetron is leaking and sparking to the ground. As you have mentioned it was stored, it is quite possible that insect can get into the oven and create soft spots. When you switch on these will create a short and make the voltage jump and in the long run damage the magnetron. So Remove cover after disconnecting , check for dirt/moisture in the cabin, if so wipe clean and dry, check the magnetron and area clean and use an jet air to clean off. Now switch the microwave power on and use a cup of water to test. If you notice any sparks shut off as the magnetron or the main HT capacitor can be faulty. Replace with same type. If not check the waveguides within the cabin for food particles that can burn and spark, check for rust that can corrode and spark when the ceramic paint has worn out. If there is heating without any issues, you can use the microwave safely

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Replace it,

This indicates a keypad control board problem.

The internal fuse has blown indicating a secondary problem, it may be one of the door switches is defective or a more serious issue.

The problem is in the keypad control board, replacement only option.

The problem is most likely caused by 1 or 2 bad door switces often the result of food partical build up, the latches will need to be replaced.

This could indicate a shorted turn in the magnetron, a cracked high voltage diode, or a shorted high voltage capacitor.

It may be a broken door open button, door open lever, or grease in the channel where the door open button moves in the control panel frame.See these files:http://wwww.microwavedisplay.com/safety.txthttp://wwww.microwavedisplay.com/disassembly.txtYou can order Panasonic parts from Encompass here but without part numbers, it may be best to call them toll-free at 866-779-5835. We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Hi Colin, On our microwave , unplug first, husband just removed thewhole outer casing of microwave and pushed the button through the back, he did not touch the control panel. Hope this helpskind regardsChristine

Take side panels off and press the button through from the back, my husband has just done this tonight on our Panasonic microwave model NN-ST477 as the door would not open. He found a piece of plastic like a hook had snapped off. The door now opens and functions normally. Took about 30 minutes to do . If and when it becomes stuck again we know that we will need a new replacement button. Hope this helpskind regardsChristine

This not a good sign, from your description it indicates the high voltage transformer is shorted possibily caused by the magnetron becoming defective. The money would be better spent replacing the microwave oven, the repairs to the present unit will be close or exceed the cost of a new one.