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Panasonic Model NN-T994SF runs for approximately 30 seconds and stops. The unit still has power to the front panel and can be restarted (for an additional approximate 30 second interval before it stops again) and does not appear to be cooking at all.

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  • Jdubya Apr 09, 2008

    Been there, done that....this symptom doesn't appear to be my problem in this case.

  • Jdubya Apr 09, 2008

    I have 120V AC going into the PC board and 9.3 V AC coming out of the power supply going to the Magnetron unit when I simulate and initiate a cooking cycle on the front panel. I was hoping you folks might be able to provide the output of the PC board to the Magnetron unit or email a suitable schematic with outputs of the components at the test points within the PC board. This would allow me to 'shoot the bug' down to the component level and save me some time and money.

  • Jdubya Apr 10, 2008

    Yes, very informative WEB pages! After performing the Magnetron test I found that I have a shorted Magnetron according to the procedure (0 ohms resistance between the terminals of the Magnetron and its metallic case). But I also wonder if I have another bug in the oven since the oven simply stops before the alloted time period is reached. I suppose I am trying to understand what regulates the timer in the microwave circuitry and why the oven would stop prematurely. Could a defective Magnetron unit have affect on this timer circuit?

  • Jdubya Apr 10, 2008

    Thanks for the help!! Good job!


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My microwave stops after 3 seconds


Saved me a possible big repair bill. Thank you.

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If it stops at 16 seconds and is a sensor model, it probably has a defective humidity sensor.

If it stops after 22 seconds, that means the controller has detected a problem, usually a problem with the inverter, controller, magnetron, or a bad connection from one or the other.

You can find an authorized Panasonic servicer here.

In Canada, you can find an authorized Panasonic servicer here.

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

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Panasonic microwave oven cuts on for two seconds then shuts off


See if this describes what's happening:
  • Put in time, push start and unit runs for 2 seconds, relay clicks, unit goes off. Cook time on display goes off and clock time comes back. Bad upper interlock switch and charred connector
If so, see http://031d26d.namesecurehost.com/mwd/safety.txt http://031d26d.namesecurehost.com/mwd/disassembly.txt http://031d26d.namesecurehost.com/mwd/doorsw.txt

Otherwise, if the digital programmer circuit / controller does not get a feedback signal from the inverter for a period of 3 seconds, the controller will stop the cook cycle.

That may be a loose connection in the wiring between the inverter, magnetron, and/or control board, or maybe one of those components has failed.


Due to the lethal voltages used and produced in inverters, I do not recommend that an inexperienced person work on these.

You can find an authorized Panasonic servicer here.

In Canada, you can find an authorized Panasonic servicer here.

If yours is not a Panasonic, please reply back with your brand and model number so we can help you.

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

Nov 03, 2011 | Panasonic NN-T994SF Microwave Oven

1 Answer

My Panasonic NN-T994 Microwave oven died today. Would run for a few seconds with a clicking sound and an electrical smell. I removed the cover, restarted and found arcing from the area of what I think is...


From your description it does indicate a magnetron problem, you would be further ahead replacing the microwave oven when you consider the expense of the repair involved.

Feb 23, 2011 | Panasonic NN-T994SF Microwave Oven

1 Answer

Time set does not complete


You didn't mention your brand or model number, but I'll assume it's a Panasonic since you posted this under a Panasonic category.

See if this describes what's happening:
  • Put in time, push start and unit runs for 2 seconds, relay clicks, unit goes off. Cook time on display goes off and clock time comes back. Bad upper interlock switch and charred connector
If so, see http://207.234.249.73/mwd/safety.txt , http://207.234.249.73/mwd/disassembly.txt and http://207.234.249.73/mwd/doorsw.txt

Otherwise, if the digital programmer circuit / controller does not get a feedback signal from the inverter for a period of 3 seconds, the controller will stop the cook cycle.

If it stops after 7 seconds, it has a problem with the inverter.

If it stops at 16 seconds and is a sensor model, it probably has a defective humidity sensor.

If it stops after 22 seconds, that means the controller has detected a problem, usually a problem with the inverter, controller, magnetron, or a bad connection from one or the other.

Display codes H95, H97, H98 or H99 mean that there's a problem with your inverter, magnetron, or digital programming circuit.

That may be a loose connection in the wiring between the inverter, magnetron, and/or control board, or maybe one of those components has failed.

Due to the lethal voltages used and produced in inverters, I do not recommend that an inexperienced person work on these.

You can find an authorized Panasonic servicer here.

In Canada, you can find an authorized Panasonic servicer here.

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

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Hi,
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Jun 03, 2008 | Panasonic NN-T994SF Microwave Oven

1 Answer

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Mst likely a blown fuse. You''ll need to unplug the unit, remove the outside cover and follow the line cord and you should find the fuse.

Replace it with the EXACT same value that was labeled on the original fuse. You'll probably be able to find a replacement at any Radio Shack store or hardware store.

Replace the cover and plug the unit back in. Hopefully nothing was damaged and the unit will play again.

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

Good luck!

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