Question about Panasonic NN-C994S Convection/Microwave Oven

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NNC2000P - Microwave does not work but convection works

We have a NN C2000P oven which was repaired in Sep. 2008.

The Panasonic guys replaced the magnetron and IGBT's.

Within a few months, the following problem is observed. When in heating mode, after about 8 second, a tick tick sound is heard and the oven shuts down.

However, the convection features work all right.

Please help.

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  • 2 more comments 
  • milindlk Feb 14, 2009

    Thanks MrMark52.

    The "tick tick sound" is more like snaping.

    I also don't understand the purpose of an IGBT (Induced gate bipolar transistor) in the circuits of the Microwave. Unfortunately I don't have the circuit diagram.

    Thanks again.

  • milindlk Feb 16, 2009

    Thanks Guru.

    1. Yes, the model was purchased in Dubai & is currently in India.

    2. Does "Magnetron" and "Inverter" mean the same part?

  • Mark Egan May 11, 2010

    If your good to work on equipment like this, I would open it up and see what's ticking. You'll also probably find the wiring diagram, which may explain what the IGBT is for.

    Let us know what you find. But I caution you, stay clear of the wiring. There are very high voltages present (up to 3KV.).

    Let us know what you find.

  • Mark Egan May 11, 2010

    Sounds like a high voltage problem in the magnetron high voltage circuit, if the ticking sounds are more of a snap/pop.

    For some reason, my mind is not letting me figure out what the IGBT is to know if it might be related.

    I would take it back to where you had it fixed and discuss the short life of the repair. Be reasonable, if something else failed to cause the problem, don't make it an issue that ti should have been caught the first time around. Just be sure the repairs are covered under a new repair warranty as well. But above all, be reasonable in your discussions.



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An IGBT is an insulated gate bipolar transistor - sort of a hybird between a bipolar transistor and a MOSFET.

These are the final output driver transistors in the high-voltage inverter.

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

It's likely a bad transistor, an electrolytic capacitor with an internal short or bad ESR or altered value, bad connection on the inverter board, a shorted diode or blown resistor, or a bad connection in the wiring.

Reputable service centers will have a repair warranty, but it may only be 30-90 days.

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

You should use a Panasonic-authorized service center so they'll have the service manual and (hopefully) experience and training to repair inverters.

In the US, you can find an authorized Panasonic servicer here.

This sounds like a non-US model. If so, visit, find your home country, then find the service / support links.

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

Posted on Feb 15, 2009

  • William Miller
    William Miller Feb 23, 2009

    The magnetron and inverter are not the same.

    The inverter is a circuit board which converts mains voltage to high voltage.

    The magnetron is the finned metal device which outputs microwave energy and is fed its high voltage by the inverter.



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