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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If it is displaying error H97, or h98, this generally means that the invertor(power supply Panasonic part
number: Z606YM300BP,) is not functioning. The magnetron may also be faulty.
Here is some more information about the part. The microwave may also
have a faulty magnetron. If you are unsure, then you should get someone
to look at the unit for you before you go buying parts.
BEWARE... VOLTAGES INSIDE MICROWAVES CAN KILL
number: Z606YM300BP, supersedes all previous versions of the inverter
used with the 2M261-M32J This Inverter is now available at a lower
cost, it used to be £60.00 plus VAT and delivery trade price.
This inverter is fitted to many of the more
recent Panasonic inverter type microwaves such as the NNC596S .Some
microwaves such as Bosch and Siemens also use this inverter as they are
rebranded Panasonic ovens. These ovens are upmarket models, some
include advanced functions such as steaming and are normally well worth
The inverter as fitted to earlier ovens with the
2M236-M42 and 2M236-M1 is also available.
An inverter microwave oven is one without a high
voltage transformer You will know you have one as it is not extremely
heavy at one end. This type of microwave uses a high power DC
converter, called an inverter, to produce the high voltage and filament
voltage required by the magnetron.
If you purchase this item for replacement in your
microwave then we recommend that you do this only if you are qualified
and aware of the dangers of tampering with electrical equipment.
Failure of the magnetron is common and at times
the inverter can fail as well. Sometimes the inverter fails on it's
own. If your microwave blows the 10 amp mains input fuse as the cooking
cycle starts then you probably need a new inverter. An instruction
sheet with basic guidelines on fitting will be provided but please do
not purchase this item unless you are confident about fitting it. We
only accept returns if the inverter supplied is defective which is
If you have one of these ovens that is not cooking then it is
worthwhile looking at the magnetron. It often shows signs of distress
As well as the inverter failing it is also possible you could also have a defective magnetron,
Good luck and thanks for using FixYa
A FixYa rating would be spot on for this information to you.
And oven may have an inverter and it may have a sensor (usually either a heat sensor or humidity sensor).
Please note that FixYa is not currently notifying us Experts when Clarification Requests are answered.
So to allow us to help you effectively (at no charge), please post a NEW problem to FixYa, and please
include your brand name and the full model number from the tag in or on
the unit, and your exact symptoms, so we can help you troubleshoot the problem and make recommendations.
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.