Question about Panasonic NN-T990SA Microwave Oven

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Panasonic microwave... You offered your suggestion as to what was the possible problem with my MW. It is about 5 yrs old, and has never been run MT. I was cooking baked potatoes when it quit. I there any way, or the best way to decide whether its the mag. or inverter that has gone bad?? Thank-you VERY much for your reply. This MW has been built-in to my cabinets. BTW..why do MW only have doors that hinge on the left side????

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  • Anonymous Mar 26, 2014

    I have got a whirlpool microoven mw 20sw model as a gift.I want to know whether its possible to bake a cake?pls rply...



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Without HV test equipment it is quite difficult to determine if it is the magnetron or inverter.

5 years is a little short for magnetron failure but it appears that this is about all you can expect these days from a magnetron - the best I have seen was 11 years. I have not seen an inverter failure as yet (although I am not a full time repair man). The main reason I suspect it is the magnetron is the short time period from start to stop - it is typical of magnetron failure in Panasonic microwaves.

As regards door hinge side, that is one of the great unknowns. I suspect it comes from most people being right handed but even refrigerators could be specified as right/left hand hinged originally and now can be changed by customers.

Posted on Nov 09, 2008


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Runs when door is closed,stops when open!Checked the three door switches;all good.The mw is 5 years old so anyone have suggestions as i would be thanking U in advance

It is possible that a relay on the control board has stuck in the closed position. You can try tapping the relays on the main control board and this sometimes breaks them free. It still may be one of the door switches but I would suspect the control board or possibly a stuck start pad on the touch panel.

Apr 24, 2015 | Cuisinart CMW-100 Microwave Oven

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Bought Panasonic NN-S766 microwave in 1997. Been great. Has begun to run 2-4seconds, blows fuse. Also makes a louder(different) hum while running. All switches look good, magnatron magnets look good. Need...

With the prices of microwave's & since you've had it since '97 that's almost 18 yrs. don't you think you can put it out of it's misery & get a new one? Check Craig's list, the penny saver or yard sales, you'd be surprised how inexpensive they are now. I use to sell Panasonic when they first came out, so many yrs. ago,. I've always had great results with Panasonic microwaves.

Nov 06, 2014 | Microwave Ovens

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No to fix it.

check the GFI breaker in your kitchen or bathroom. It could have tripped. Plug a light in the socket to test it.

Mar 05, 2012 | Microwave Ovens

1 Answer

Wife was cooking food, she says she heard a big pow and saw a blue light in the MW. Now everytime we turn it on it jumps the breaker. Everything else works fine.

It sounds like the Magnetron that produces the microwave energy that heats the food has failed and shorted out which is triggering the Circuit Breaker due to the overload. You could try taking it to a repair shop, but with the cost of labour and parts these days, it is probably more economical to buy a new oven especially if it more than 5 Yrs old..

Feb 26, 2011 | Microwave Ovens

1 Answer

Does not matter what the setting is on,the microwave will only run for 2 min. and then shut off. It is only 5 yrs old.

Please check all the poer connections on the power side, the magnetron section. specially the capacitor. Also if there is fault on the control processor board.
This can trip off the power and reset. possible loose connection or even if the outlet power - if it is lower when the microwave starts.

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I have a over the range mw, the controls work but the fan,light and microwave itself has no power.

If still under warranty--take it back--serious problem. If not a qualified person will have to check the door switch & interior electronics. There is a faint chance that a wire may not be connected inside. If it is over 3 yrs. old --have magnetron tube checked also.

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1 Answer

Mw oven totally dead. 2 year old panasonic

No sorry there is none... look what usually happens is the magnetron, or high power diode, or Oower Supply goes faulty, a magnetron can cost between $95 - $150, or more...and usually that is NOT the only part that will/would need replacing. Cut your losses, and get a firm "Quote" from a repair center, or get a new one, with a 5 year Warranty.

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1 Answer

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Hi! the problem you have stated indicates that the magnetron its not functioning, check for busted fuse.

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you would need to take the door apart. however by doing that you will cause more damage than just lettin it be unsightly. if the mw is 5 yrs or older wait for it to break and get a new one

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1 Answer

Model JVM1860CF001 not heating...

If you feel comfortable doing so, you may want to check the capacitor. Burning odors however are usually caused by either the magnetron or HV transformer.

Nov 09, 2017 | Microwave Ovens

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