Question about Panasonic NN-C994S Convection/Microwave Oven

2 Answers


I replaced low voltage transformer on PCB of display board , and when i started for a while all was ok but next day when i started microven once again this transformer got opened and my oven stopped working, on transformer there are 2 terminal marked P1 and P2, can some one explain why this is happening , is it correct to loop P1 AND P2 externally(as i believe this are looped inside transfomer,and due to some reason gets opened) Please guide on possible cause and rectification

Posted by on

2 Answers


I had looped externally P1 and P2 and now it is working , to assure myself I also checked current in primary of transformer it was measured to be from 300 mA to 600 mA when I started to use microoven. For safety I had now fixed 2 Amp fuse between P1 and P2. Is that all ok. To add I checked all voltages mentioned on PCB viz. 30volt, 5 volt etc which on measuring were found almost ok. Any comments please

Posted on Mar 29, 2007

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Panasonic Master
  • 8,795 Answers

There is something on the secondary side which is drawing too much current. I would check all electrolytic capacitors, zener diodes, transistors, and voltage regulators.

Posted on Mar 29, 2007

Add Your Answer

0 characters

Uploading: 0%


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


3 Points

Related Questions:

1 Answer

Kenmore microwave mod. 721.80412500 does not heat, timer,lights,fan ok.possible to try a fuse,before calling sears?

If the fuse were blown, You wouldn't even get a display. If you're handy with a multi-meter, and feel somewhat comfortable making electrical tests, the first thing to check is whether the problem is coming from the low voltage (control) side of the oven, or the high voltage side (transformer, magnetron, capacitor and diode).

Unplug the oven and remove the cabinet cover. Before reaching into the chassis, discharge the capacitor by shorting between the two sides with a screwdriver or similar tool. It can store up to about 2000 volts, and can hurt you badly. A brief touch with your shorting tool is all that's necessary.

Disconnect the wire lead that goes from the power transformer (the largest component on your oven's right side (as you face the door), to the capacitor. Insulate it against any metal contact by wrapping electrical tape around the connector.

Set your meter to test for house voltage (the 200VAC range). Plug the machine in and select a cooking cycle. While it's trying to cook, place your meter's leads on the wires coming from the control board to the primary terminals on the transformer. You're looking for a reading that's reasonably close to 120VAC. If you don't get enough voltage, the problem is with the control board. If you do get the required voltage, the problem is in one of the high voltage components.

Write back with your results for further diagnosis.

Dec 24, 2010 | Kenmore Microwave Ovens

1 Answer

Hi, I have a JVM1490 that is dead. I have chased

There should be a "mini-manual" (tech sheet) hidden inside the unit
behind the control panel or hidden on the left side behind the grille, which is
very helpful when troubleshooting, testing, and locating components.


It *may* have the part number of the low voltage transformer, possibly on a loose sheet inside the mini manual.

Otherwise, you can find links to helpful exploded view diagrams and part ordering help here.

I recommend that you bookmark that link to your favorites.

There should be a part number on the label of low voltage transformer.

The GE part number will be something like WB##x##### and the Samsung number will be something like DE_#######.

The Samsung part number is almost always cheaper.

Feel free to contact me directly if you need more help.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

May 13, 2010 | Microwave Ovens

1 Answer

Microwave won't work

Check the AC fuse in side the oven. If the fuse is ok chek the low voltage transformer . If the primary winding is open replace the transformer.

May 25, 2009 | Frigidaire FMT148GP Microwave Oven

1 Answer

Kenmore Micro/Oven fuse keeps blowing

Disconnect the connector to the primary winding of the high voltage transformer. Put a new fuse . If the fuse is not blowing the problem may be in the secondary side of the high voltage transformer. Chek the highvoltage diode, capacitor, magnetron respectively. you can also check the primary winding of the low voltage transformer.

May 23, 2009 | Microwave Ovens

1 Answer

No power problem

Check the AC fuse and the low voltage transforer primary winding open. If it open replace the transformer or rewind it.

May 22, 2009 | Sharp R-316FS Microwave Oven

2 Answers

Any Whirlpool Microwave Techs out there...Please help a fellow tech

hi mike,

I’m sorry to tell you this but; I wouldn't recommend using a different transformer, even if it's the same size, it could cause serious damage. The HV transformer should only be replaced with the exact replacement part.

Mar 21, 2008 | Microwave Ovens

5 Answers

Emerson Model MWG9111SL Microwave not always working

ok i just opened mine up on counter and found that the white wire on the high voltage transformer had been loose and melted so i put a new female spade connector on and it works fine. i suspect that from a year of use and humm from transformer had loosen it and gotten hot thus loosing connection and getting dirty causing it to overheat and burn off plastic sheilding. easy fix!!!

Feb 14, 2008 | Microwave Ovens

1 Answer

My PCB transformer primary is always blowing off what could be problem

Is your line voltage correct? That needs to be measured, perhaps even monitored. Is it possible you have installed 120 volt replacements into a 220 volt model? Otherwise, there is a component shorted on the control board, such as a rectifier diode, zener diode, filter capacitor, or transistor. This would call for old-style troublehsooting. It's possible you have a bad sensor, but I doubt it. They could be disconnected or bypassed for test purposes.

Apr 09, 2007 | Panasonic NN-C994S Convection/Microwave...

1 Answer

NO power display dimesnion 4 range national microwave NNC 2000P MODEL

on front panel there is alow voltage transformmer the primary side isopen circuit replace

Mar 20, 2007 | Panasonic NN-C994S Convection/Microwave...

1 Answer

Power but no display to unit

Not sure about the Neff brand, but in general you'd want to check for 110VAC power on the primary side of the low voltage transformer on the control panel / board. If that is present, check the secondary for voltage, about 12-30VAC. If the unit has a VFD type display, there will be a heater filament supply, usually around 2.5-6VAC. Also look for bad connecitons on the VFD. If those voltages are present, check connections on the board, look for bloated / bulging capacitors, shorted diodes, breaks in the board, etc. Also look for thermal cutouts and thermostats. If this doesn't fix it, can you take several photos of the inner parts and circuit boards?

Sep 26, 2006 | Neff H7871A2GB 800 Watts Convection /...

Not finding what you are looking for?
Panasonic NN-C994S Convection/Microwave Oven Logo

Related Topics:

112 people viewed this question

Ask a Question

Usually answered in minutes!

Top Panasonic Microwave Ovens Experts

William Miller
William Miller

Level 3 Expert

8795 Answers

Donald DCruz
Donald DCruz

Level 3 Expert

17129 Answers


Level 2 Expert

224 Answers

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

Answer questions

Manuals & User Guides