Has Panasonic rectified its inverter design problems?
(I previously wrote a long post about this topic and it unexpectedly disappeared with one misplaced keystroke, so apologies in advance if I have repeated my posting. It?s always a good strategy to compose long (winded) postings in Word first ?)
I bought my Panasonic stainless over-the range model NNP-294S in Aug 04 from a Sears clearance outlet in Canada. It wasn?t actually installed or used until about a year later pending my kitchen remodel. You are never really sure of the usage history with clearance outlet purchases, but mine looked brand new (although it had a ding on the left underside). I loved its sleek, minimalist appearance and still think this is one of the best looking units on the market.
Within about 6 months (late 2005/early 2006) it started turning off after 3 seconds, although it would always eventually start working again. There were no funny smells or noises accompanying the shutdowns and when it was working, it worked very well. Since the shutdown problem was sporadic (about once a month) I tolerated it for many months. In Aug 06 I discussed the problem on the phone with a Sears technical advisor, who said it sounded like the inverter but it wasn?t available as a part. I left things alone as for various reasons I was very reluctant to go through the hassle of pulling the unit out; I also found that the shutdowns were usually quickly resolved by firmly shutting (not slamming) the door. However my gut told me it would be a good idea to keep my Sears maintenance agreement current in case of eventual catastrophe.
Alas, my intuition proved accurate. Almost a week ago the unit finally bit the dust altogether ? no display, power, lights or fan. I called Sears and they confirmed that the inverter was not available as a part from Panasonic and Sears doesn?t repair them, although they would send someone to look at it. In the meantime I called Panasonic Canada, who said the inverter was not replaceable as a part (and never had been) because the inverter was repairable at the component level. They said that Sears doesn?t like to repair them because ?they?re lazy.?
The Sears tech who attended found that the fuse was gone, and unfortunately the only fuse he brought with him was also defunct. However he agreed from my description (and my previous conversation with a Sears tech) that the shutdown problem was likely an inverter issue. Therefore it has now become a matter to resolve with the Customer Service department, who I expect to be hearing from within the next week.
Sears currently sells a newer version, NNP-295S, which appears from the specs to be identical to mine except that there are 4 fan speeds instead of 3 and 450 cfm instead of 300. Apparently the inverter IS available as a replacement part for this model.
Based on the above, these are my questions:
1. I read MicrowaveSvc?s postings about the design weaknesses of the inverter. Would Panasonic have ?discontinued? this part so soon for that reason? Is this particular model a lemon? Some postings on another website suggest that one should avoid Panasonic inverter models at all costs.
2. What is the likelihood that Panasonic has resolved the design flaws around the inverter for the current model NNP-295S? Surely they must have become aware of the problems with my model and taken steps to address them? (she said hopefully)
3. If Sears offers me some cash towards buying a replacement unit, would it be better to buy the current model or keep my current unit and get it repaired at a Panasonic service depot to ?repair the inverter to component level? as both MicrowaveSvc and Panasonic Canada have suggested? Will I get a more robust/long-lived inverter that way?
Any advice is greatly appreciated!
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Re: Has Panasonic rectified its inverter design problems?
Parts for this model (including the inverter) can be had via Panasonic in the US at http://www.pasc.panasonic.com/epartr
Canada's safety requirements may be different enough from those in the US that Panasonic does not make the inverters available as a spare up north.
Any competent electronics technician should be able to fix the inverter, but many appliance repair shops (and appliance techs) do not do component-level repair.
Everyone has his specialty. You may have to call a TV shop to get this kind of service.
I would definitely suggest you get a servicer who is authorized to do warranty service on Panasonic microwaves, even though this one is not under full warranty.
Follow the "servicer locator" link at the page mentioned above to find such a servicer.
I would suggest that you include the last letter when you refer to your model number, such as NNP294SF or whatever the last letter is.
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It is probably an error code, what is the unit doing, does it heat, time down, run but no heat??? Etc Brand???
I'm betting it is a Panasonic and it has a bad mag and or Inverter. . probably best to replace the unit if that is the case. Price wise the inverters are expensive and I have had bad NEW ones sent to me. Personally I really do not like the inverters, they are certainly not as reliable as the transformers, capacitors and rectifiers, that it replaced.
A "zapping noise" usually indicates a problem in the high voltage circuit. If it's an inverter oven, it should have provided you with a fault code. If a non-inverter, the most likely causes are a shorted high voltage rectifier or bad magnetron. But there are many other possible causes.
And oven may have an inverter and it may have a sensor (usually either a heat sensor or humidity sensor).
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I do not have service data on this model., but an inverter model will normally have 2 high voltage capacitors located on the inverter board. One or possibly both is likely shorted.
Due to the lethal voltages used and produced, I do not recommend that an inexperienced person work on these.
If you or someone you know wants to look into this, we have *critical* safety, disassembly, and troubleshooting info at our site, and our link is at our listing here on FixYa: http://tinyurl.com/yzjozk
If you described this to Panasonic very carefully, and they said it's normal, then I would say keep using it until such time that you get other symptoms.
The inverter has some parts mounted on a large chunk of aluminum called a heat sink. It draws the heat out of the parts and the heat radiates and/or convects away. This keeps the circuit parts from overheating.
As long as you have good air flow through the vents, it sounds okay.
Frannie, this is the way the oven is designed. There is a thermostat in there that is normally open. The thermostat will close at approx. 140 degrees and start the fan. When the temps. cool to about 104 degrees the thermostat will open again and the fan will shut off. Catriver..post back.
Yikes - it looks like composing in Word replaces apostrophes, quotes and dashes with questions marks? How annoying.
Thanks for your helpful suggestions. There are several Panasonic authorized repair shops around here (Vancouver, BC) that could fix it. Sears refuses to repair it themselves and has offered 75% of my original purchase cost, or about $350, towards a new microwave. This means I have to cough up another $350 since they are $700 Cdn. That doesn't seem right. If I want to keep the existing micro and get it fixed, it may cost about $100 but Sears won't pay for it.
MicrowaveSvc, could you please comment on my 3rd point in my original posting? Would I be better off -- in terms of longevity and reliability -- to buy the new model or to fix the one I have? In other words has Panasonic done anything to "improve" the inverter on the latest model?
Thanks MicrowaveSvc for helping out a northern neighbour. Here's what has transpired in case you or another owner of this particular model are interested.
I decided this weekend to order the new model because they are nominally on sale at Sears this week ($30 off) and I figured that by the time I factored in the cost of repairing my existing unit on my own, a new one would be a net extra outlay of about $200 -- and, as you note, it will be a brand new unit with new warranty. Also, Sears won't warrant my current unit anymore and are refunding my full warranty cost, so I had to decide one way or another.
I emailed Panasonic last Friday and they responded to several questions. They said that there was no design flaw in the inverter board (oh really?) and it is the same board in all their microwaves. The inverter is available as a part IF the service centre cannot repair the board, but most times the service centre has no problem repairing the board. (I wonder why they won't supply it to Sears then??)
Let's just hope that I don't have the same problem with the new one. Panasonic's warranty is 2 years and buying it on my Visa card extends it another year.
I also had a conversation last Friday with the assistant to Sears Canada's president, expressing my dissatisfaction that Sears' refusal to repair my microwave, which I was quite happy to keep, was unnecessarily forcing me into spending money for a new one, and I thought they should improve their buyout offer. He was corporate arrogance personified and well rehearsed in spouting Sears policy. He said outright that Sears was not prepared to negotiate and there would be no further "escalation of the process." I could write a letter to the President if I wanted to, but he wouldn't read it. At least he was brutally honest, I suppose. I doubt if Sears operates any differently south of the border.