Question about Panasonic NN-C980 Convection/Microwave Oven

3 Answers

Panasonic Microwave NN-C980-B buzzing noise but it still works.

I have a Panasonic NN-C980-B its been making a buzzing noise for a couple seconds when the microwave first turns on. it seems to work properly besides that. the other day it made a noise and then smells of burning components came out of it. but again, it still worked ok.
Today I opened it and all I noticed that there is a Zener Diode burned up. ZD703 is burned and beside it is ZD704. The solder joints of the main transistors look a little tired so I'll clean them up but do you know what these Zeners are so I can replace them?

Posted by on

  • 8 more comments 
  • Barry Beadman
    Barry Beadman Feb 16, 2009

    the diode in question is a tiny zener. it is about the size of standard glass 1n4148. It is not connected to any heat sink. the board is a little burned and the solder connections on the main components connected to the heat sink look overheated. I'm wondering if it was merely a heat issue initially. I'm in ottawa too. maybe I can show you the board :)



  • Barry Beadman
    Barry Beadman Feb 16, 2009

    the mag measures open. Yes the zeners are on the inverter board. sorry for not making that clear.
    i did find a schematic on scribd but its not exactly the same...http://d.scribd.com/docs/11nt6gyhx8hucv9...
    do you think you could tell me the voltage of these zeners? I'll swap them and hopefully with clean solder, it'll work fine. the buzzing sound is almost surely coming from the inverter board. but i didn't want to stick my head too close :)


  • Barry Beadman
    Barry Beadman Feb 16, 2009

    this schematic has an accurate depiction of my inverter board.http://www.eletrodomesticosforum.com/dow...

  • Barry Beadman
    Barry Beadman Feb 16, 2009

    Its a 10V zener. 0.5W pn AEDZ10ES2T1

  • Barry Beadman
    Barry Beadman Feb 16, 2009

    i replaced the Zeners and replaced the solder on all of the Large transistors.
    its still works but the buzzing noise is still there. the buzzing is only in the first second when the Magnetron is turned on and off.
    when its running it sounds normal.


  • Barry Beadman
    Barry Beadman Feb 17, 2009

    I sent a note to the Panasonic Service Depot to get a price on a new Inverter Board. I'll run this one till it pops and just replace it.
    thanks.


  • Scott Wiuff
    Scott Wiuff May 11, 2010

    I looked a little more at that particular model and it has the inverter board I see. That's what I assume the zener is on. Not sure what to tell you. I'm surprised it didn't come up with a error code but then again about all that would tell you is there is a problem with the board but nothing specific. Sometimes when the mag shorts it takes out the inverter. I would measure the mag leads to ground and they should be open or 20M or so. If you have both a mag and inverter bad it's probably time for the bone yard. I live in Owatonna MN.

  • Scott Wiuff
    Scott Wiuff May 11, 2010

    where is the diode fried? Usually a buzzing sound like that comes off the high voltage diode by a tin can capacitor. one side of the diode is connected to the case. Is that what it looks like?

  • Barry Beadman
    Barry Beadman Jun 02, 2010

    my board finally popped.
    the transistor Q702 blew. its a 1M30D the rest is hard to read because its burned off. can anybody confirm?
    I looked online and cannot find info on this transistor. anybody have a cross refence for it? it appears to be a BJT. the board is labeled with an E for emitter.

    Munson1 - did you notice that you have a crack in C703?



  • Barry Beadman
    Barry Beadman Jun 02, 2010

    my inverter board finally blew. transistor Q702 burned up. it seems to be a 1M30D the rest is burnt off. can anyone confirm?
    is there a cross? I cannot find info online for this transistor. I assume its a BJT as the board has E labeled on one pin.

×

3 Answers

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

All:
I have a 2003 Sears Ultra Wave microwave 721.63682300 with a similar problem. A few months ago it started giving off short buzzes when turned on. That stopped but then I noticed that everything took twice as long to heat up. After quite a bit of teardown&inspection I found a circuit break in the inverter board leading to ZD704 diode (pictured). I will now try to find a replacement diode to see if replacing will fix it. Thanks for your postings.

Panasonic  Microwave NN-C980-B buzzing noise but i - 86ab7c4.jpg13a5e0e.jpg

Posted on May 05, 2010

  • munson1 Jun 02, 2010

    Joust:

    You may want to trade out the board at this time. When you start finding multiple problems on your board the economics of piecemeal fixes start to overwhelm. The price of your 10V Zener 0.5W pn AEDZ10ES2T1 cost me less than $2 for one (I could buy 400 in bulk for less than 5 cents each) but the cost of shipping/handling was $7.50 for that diode the size of a pinhead. But you'll note from the picture I posted that a transister is also cracked; not shown was some scorching of traces. When you see multiple problems, you're likely to have more that you can't see. For me, the economics at that point dictated that it was cheaper to replace the whole board, a bit over $100 in the end. After one month, no noises, normal power, no error messages. Good luck.

×

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

I have a panasonic convection/microwave. Last night, after I cleaned it, using oven cleaner on a sponge, it made a loud humming noise after running on microwave for about 10 sec. It does not make the noise when using the convection oven. I don't know if any heating occurred during the brief time before the humming started. Is there something that got wet and needs to dry out, or needs cleaning? What might be wrong? Should I try using it again, or would that make the problem worse?

Posted on Aug 24, 2011

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that gotĀ 5 achievements.

    Governor:

    An expert whose answer gotĀ voted for 20 times.

    Scholar:

    An expert who has written 20 answers of more than 400 characters.

  • Expert
  • 87 Answers

That's good that it worked for you! Ya it's kind of hard to find out where it's coming from when you don't want to get close to it. As long as it's working and the fan is running to keep it cool, you'll just have to se what happens!

Posted on Feb 16, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Microwave makes buzzing noise when using


If buzzing but not heating it could be $10capacitor or diode.

Oct 13, 2014 | Panasonic Microwave Ovens

1 Answer

When started,light& turntable operate normally,but no heating by microwave. Transformer normally sounds smooth,but now makes rattle or vibrating noise,like something is loose.


Check the door safety intertlock micro switch for proper behavior. If it is faulty, the oven will think the door is open and will not turn on the magnatron.

Sep 22, 2010 | Panasonic NN-C980 Convection/Microwave...

1 Answer

Panasonic NN-C980B stopped working. Blown fuse.


Sometimes when the mag shorts it takes out the inverter. I would measure the mag leads to ground and they should be open or 20M or so. If you have both a mag and inverter bad it's probably time for a new oven.

Apr 19, 2010 | Panasonic NN-C980 Convection/Microwave...

1 Answer

Microwave stopped working


Hi,
Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Microwave Oven Basic Troubleshooting Tips
http://www.fixya.com/support/r5508031-microwave_oven_basic_troubleshooting

heatman101

Oct 16, 2009 | Panasonic NN-C980 Convection/Microwave...

1 Answer

Micro wave made a popping noise now does not heat up food as hot


The popping noise was probably the capacitor or high voltage diode blowing.

Test the high voltage capacitor, the rectifier diode.or the magnetron.

The diode and capacitors can br tested. The capacitor must be allowed discharge before testing, or you risk to get electrocuted, even if power is off. Capacitors can get discharged by shorting their two contacts.
Replace the magnetron if the checks and all of the high voltage component tests are good, but the unit still does not heat.

All locations, and description of this parts can be located using the diagram here: Counter top.

Parts must be tested to find out what is wrong.

Remember that microwaves are potentially dangerous devices if not repaired properly, the job must be done by a competent person.
A microwave energy leakage test must always be performed when the oven is serviced for any reason.

Regarding parts, contact the seller here to purchase parts.

Apr 08, 2009 | Panasonic NN-C980 Convection/Microwave...

1 Answer

Operates for 3 seconds on microwave then stops


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.

It could possibly be as simple as a loose connection in that area. The repair shop your friend used may not have been Panasonic-authorized.

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

I would recommend that you contact your nearest Panasonic-authorized servicer.

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

Sep 15, 2008 | Panasonic NN-C980 Convection/Microwave...

1 Answer

Microwave light door turn table works but does not heat up food


In most cases, this is a problem with the inverter or a bad magnetron.

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

I would recommend that you contact your nearest Panasonic-authorized servicer. You can find one here.

We're happy to help and we appreciate your thoughtful rating of our answer.

Jul 01, 2008 | Panasonic NN-C980 Convection/Microwave...

1 Answer

Buzzing Microwave


the buzzing is the magnatron tube juicing too thousands of volts before emmitting the micro-wave radiation to what your cooking that turns molecules 180 degrees around... guess that friction is what really heats it.
radar ovens is what they use to call em and even people would stand in front of big ones to warm up long ago...lol canibles will love that.

Jan 11, 2008 | Panasonic NN-T990SA Microwave Oven

1 Answer

Microwave


That's probably because there's still steam (humidity) in the cavity after the first bag is popped.

After the first bag pops, try wiping down the walls and ceiling and leaving the door open for a couple of minutes.

You might even blow or fan the air out of the microwave.

We're happy to help and we appreciate your thoughtful rating of our answer.

Jan 02, 2008 | Panasonic NN-C980 Convection/Microwave...

2 Answers

Microwave oven problem


In most cases, this is a problem with the inverter or a bad magnetron.

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

I would recommend that you contact your nearest Panasonic-authorized servicer. You can find one here:

http://www.panasonic.co.in/

Oct 16, 2007 | Panasonic NN-C980 Convection/Microwave...

Not finding what you are looking for?
Panasonic NN-C980 Convection/Microwave Oven Logo

1,791 people viewed this question

Ask a Question

Usually answered in minutes!

Top Panasonic Microwave Ovens Experts

William Miller
William Miller

Level 3 Expert

8820 Answers

Donald DCruz
Donald DCruz

Level 3 Expert

17129 Answers

Devabhakthuni...
Devabhakthuni...

Level 2 Expert

224 Answers

Are you a Panasonic Microwave Oven Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...