Question about Panasonic NN-S740BA Microwave Oven

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Panasonic Microwave Model # NN-S740BAW 7. AUG 2000 BUILD. Makes a funny, rattling sort of hum then shuts off after about 4 - 6 seconds. It was working fine last night, but nothing doing this morning. Worth fixing? I've packed this beast all over the country for the past decade. Not exactly emotionally invested, but hate to abandon it after all that history.

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Posted on Jan 02, 2017

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MicrowaveSvc
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SOURCE: Microwave shuts off after 3 seconds

Although your model number doesn't seem to show up, the NNS950-series units are powered by an high-voltage inverter. And yours has failed. While an inverter (switched-mode power supply) is more efficient from a power consumption standpoint, it is more complex, thus more statistically prone to fail. These should only be examined and worked on by someone who has the necessary technical qualifications. Seriously. Often the machine-soldered connections in a microwave inverter are too weak, so they eventually fail, especially if heat is high in the area. They sometimes fail catastrophically. When not catastrophically damaged, you may hear clicking or squealing and may smell an electrical odor, which is sometimes obscured by the cooling fan. Sometimes a whole new inverter is cheaper than the time and labor required to fix the old one. If a technician is willing and able to troubleshoot and repair the inverter to component level, it will may be expensive, but may be worth it, especially if he or she will resolder and reinforce connections as needed as part of a thorough repair. That could easily make your inverter beter than a new one! You might be able to get some verbal estimates if you call Panasonic-authorized appliance / microwave repair shops and ask then specifically about inverter component-level repair and simple inverter replacement costs for your exact model number.

Posted on Dec 28, 2006

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MicrowaveSvc
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SOURCE: panasonic microwave oven model nn-p994sf

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.

Posted on May 22, 2008

MicrowaveSvc
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SOURCE: Panasonic NN- A712 combination Microwave 1000w - Switches off after 20 seconds

The 22 seconds is the giveaway.

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.

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

Posted on Jul 19, 2008

  • 1 Answer

SOURCE: Panasonic Model No. NN-S933BF Microwave Oven

could it be that i didn't follow the manuel because i got it second hand or is it because something is wrong with it,and i have to get it fixed.

Posted on Oct 21, 2008

MicrowaveSvc
  • 9085 Answers

SOURCE: Panasonic NN-P295 Cooktop Light not working

We see (and repair) this a lot. The problem is on the control panel, which we regularly repair nationwide by mail for $39.95 postpaid in about a week.

At our Web site, you can get details of our service, plus we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

This light failure often occurs when a bulb goes out and the filament shorts, or when the bulbs are removed or installed without first unplugging the oven from the power line. Either can cause such a failure on the controller.

This can often also affect the exhaust fan operation, too. The lights and fan can be inoperable or stuck on too.

Feel free to contact me directly (and please remind me of your full model number) for more information & help.

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

William E. Miller
prototech@usa.net
http://www.microwavedisplay.com

Posted on Jan 23, 2009

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If it stops after 22 seconds, that means the controller has detected a problem, usually 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.

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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could it be that i didn't follow the manuel because i got it second hand or is it because something is wrong with it,and i have to get it fixed.

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