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ApplianceGuru.com: The Samurai Appliance Repair Forums > Do-It-Yourself Appliance Repair Help > The Kitchen Appliance Repair Forum > Panasonic Inverter Microwaves - Advanced or retrograde? |
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iceman Master Appliantologist 
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Konichiwa, Honorable Samurai Appliance Repairman; Along the path to appliance enlightenment I once obtained, by means of money, a 1300W Panasonic "Inverter" Microwave from Sears. (About 5 Years ago). Apparently, the master appliantologists at Panasonic had discovered a way to make a man sized microwave (2.1 cu. ft.) that weighs less than a small child. No more heavy transformer, no expletives required during balancing it end-in with one hand, while plugging it into the hood fan cavity with the other. Regrettably, I have on two occasions had to disrupt the tranquility of my garden kitchen by making use of those same expletives which I had so painstakingly conserved during installation. (Well...three times, if you count my son’s popcorn-fire incident.) On the other two occasions, I observed spectacular bright blue flashes coming from outside the cavity, on the bottom of the microwave, even mildly sooting the surface on which the microwave rest. This was followed by that unmistakable smell which I like to think of as “Who let the smoke out of the semiconductors?” On the first occasion, one year into “quest for fire”, the radiation device in question was under warranty. The friendly Sears service department was more than happy to replace my inverter board, and ding Panasonic for the courtesy. On the second occasion, Sears was ready and willing to relieve me of $135 or so for the same courtesy as the warranty had long since expired. I declined, since the inside of my microwave was pretty scorched from the popcorn incident two years prior, and since I concluded that this product failure was not a one-time freak accident, but rather a failure one could look forward to on a regular basis. This is no doubt owing to the fact that the Panasonic appliantologists had clearly not corrected their design inadequacies. (Whether this is due physical inadequacy in other dimensions of their journey, or a simple result of greed on the part of the Panasonic (or should I say Matsushita?) corporation, this is difficult to determine.) Certainly my own designs have always been very reliable, so perhaps there is a correlation between endowment and design quality. Perhaps by ‘extension’, Matsushita Corporation is just the innocent victim of their own winky impaired appliance design community, who is to say? It is clear to me now however, that for whatever reason, the Master Appliantologists (I choose the second word with some hesitation) who perpetrated this horrible joke on us “innocently trusting in Panasonic quality average-Joe-consumers”, are completely reprobate, and have no intention whatsoever of correcting their design abomination. Oh no! In fact Panasonic is still enthusiastically perpetrating (or should I say prosecuting?) this hoax here in North America with great zeal. I came to this conclusion just this past week, when in passing I mentioned my experience to a fellow appliantologist whereupon he informed me that he has had the same repair performed twice himself, under Sears Warranty, on his Panasonic Inverter Microwave!!!!! Meanwhile Inverter technology is being gleefully promoted in the Panasonic brochures as though it were a feature and a benefit and not the horrible design failure which we now all know it to be. As a public service to your honorable readers, I post here, for their benefit, the following caveat: Keywords: Panasonic Microwave Review Reviews Inverter Comparison Shop Price Quality Product Failure Unhappy. Would not buy again. DO NOT BUY PANASONIC “INVERTER” MICROWAVE OVENS They will break down because they have a fundamental design flaw in the inverter circuitry which has not been corrected, even though warranty returns must be giving some ‘hint’ of the problem. Fellow readers, please post if you have had a similar experience, or if you think I am all wet. In the latter case, I will be happy to edit this post appropriately. Honorable Samurai, it is Matsushita Corporation who should come to my kitchen, slice open their collective bellies, and spill their steaming entrails onto my floor, not you. I remain your humble student. Last edited on Sun Apr 24th, 2005 10:06 am by iceman |
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iceman Master Appliantologist
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A Haiku in honor of Matsushita design excellence: Inverter Oven Panasonic says its good Fix it once a year! Last edited on Mon Apr 25th, 2005 04:06 pm by iceman |
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The Seven Master Appliantologist
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Dear iceman, It is sad to hear your sad experience but glad that we have learnt. You should be re-classified above " the Master Appliantologists". Hope our Honorable Samurai Appliance Repairman could take the appropriate action as he likes. I don't have "1300W Panasonic Inverter Microwave" nor any other microwave in the "hood fan cavity". Have only a simple Panasonic microwave oven on the countertop. I have two queries in mind. (1) Is "Inverter" technology "wrong" or "bad"? (2) Is the "hood fan cavity" a good place to house a microwave oven? I don't have any solid answers but some simple thoughts. a) With the advent of power electronics, "heavy and large" electro-magnetic devices (transformers, switches, etc) could be replaced by "light and small" power electronic devices (inverter, triac, SCR etc). No one likes to carry a "heavy" note-book PC with a heavy transformer. An aeroplane will not able to take off if heavy transformers are used in place of the inverters. Electro-magnetic devices are "well-proven" and power electronic devices are "to be well-proven". It takes time and experience for an advanced technolgy to "mature". b) The hood fan cavity is the worst place in the kitchen where "heat, moiture, oil vapour etc" are concentrated. You are really cooking the "microwave and its inverter" there. Electro-magnetic will have a higher tolerance than power electronic in this condition. Iceman will become "vapourman" there! Wander if you could post your microwave oven for us to view! Thanks. The Seven |
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iceman Master Appliantologist
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Hi Seven, You raise two good points: 1) Can we cut the Panasonic engineers some slack, since they should be recognized for attempting to improve microwave technology by employing modern advances in semiconductor power electronics and, after all, nobody gets it 100% right the first time? 2) Isn't iceman's microwave a special case because it is in a harsh environment? Regarding the second point: The Panasonic Microwave in question lived in a special hood-fan cavity that was designed to hold a (very large) microwave. It replaced an even larger Toshiba whose uP power supply went out of regulation rendering it insane but still capable of cooking, just randomly. The oven heat and cooking gases were routed on either side of the microwave cubby hole in special integral ducting in the hood fan unit, and were expelled back into the room 10 inches above the microwave, after passing through two sets of coarse, then fine filters above the microwave oven (one set on each side of the microwave). There was an air gap of approximately one inch on either side of the microwave between the microwave and the ducting and about 5 inches above the microwave. While it is possible that would result in elevated temperatures in the vicinity of the microwave cubby hole, the temperature in that locale was never more than 5 to 7 C above ambient. Also, the microwave was rarely operated at the same time as the stove. The microwave outer surfaces never became contaminated with grease, so I am reasonably confident that this was not a contributor to internal contamination. I have also visually verified this by bringing a special TORX driver with a hole in the center to remove the tamper proof screws home from the office and opening the oven up to survey the damage. Conclusion: no particularly harsh conditions existed in the operating theater of the defective microwave oven. Regarding the photo, I would love to, but I have recently moved and while the microwave accompanied us, the hood fan unit did not. The hood fan unit was manufactured by Broan in approximately 1977. I have tried to find a picture on the internet, but have not succeeded. I realize now what a unique piece of equipment that was. For example, the fine filters had actual charcoal particles in them. Regarding the first point: I applaud Panasonic's attempt at innovation. I am all for miniaturization (except in two specific cases that come to mind) and I am all for advancing the state of the art. However, I also work for a large corporation, and I have worked in a consumer electronics division in that corporation for a period in my career about seven years ago. The name of the game in consumer electronics is cost-reduction, in fact that is the game in every division now. Cost reduction design is where the men are separated from the boys. Any knave can reduce the cost of a circuit, but it takes a master to do so while retaining the same features, and level of quality. One of my colleagues event added functionality on one of our products while cutting the cost to one quarter, when others scoffed and said he was doomed to fail! More importantly, if the warranty return rate exceeds say 5%, then you know you have a design problem, and responsible companies take action to rectify the problem. Finally, if the design problem is causing fires, that usually gets lot of executive "help" in addition to the regular "support" from product management. This is the purpose of my post. Do other owners of Panasonic Inverter technology have the same experience as I, or are the four instances of failure I am aware of simply statistical outliers? I don't know, so at this moment a more reasonable chap might be unbiased. Perhaps it was premature for me to insult the honorable Panasonic design engineers, but in my books, if three-five years elapse and the problem is still not fixed, someone is asleep at the switch, or worse, negligent! Perhaps I am being a little overly defensive. When I was ten years old some roofers near my house called me a paranoid little weirdo - in Morse code! That has always stuck with me...  Last edited on Mon Apr 25th, 2005 02:05 am by iceman |
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Samurai Appliance Repair Man Fermented Grand Master of Appliantology 
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The Seven wrote:You should be re-classified above " the Master Appliantologists". Agreed. Done. Very informative post, Iceman. I think is is we who are your students on this subject.  Last edited on Mon Apr 25th, 2005 02:11 am by Samurai Appliance Repair Man |
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The Seven Master Appliantologist
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Master Iceman, Congratulation on your promotion! Thanks very much for your very sarcastic enlightenment and extreme analytical and unbiased explanations. Would like to learn more from your vaulable experience and to be your obedient student (not a knave). The Seven Last edited on Mon Apr 25th, 2005 04:10 am by The Seven |
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Jedi Appliance Guy Sublime Master of Appliantology 
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Heck, I knew he was smart more that a month ago when he got this one right. |
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iceman Master Appliantologist
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Hi Seven, I am sorry if I came across a little sardonic. I was trying to be funny, but I would be the first to admit that I have a slightly bent sense of humor. Seven, I very much enjoyed your commentary on the thermostat problem, and I concluded from it that you are a deep thinker, and someone from whom I can learn much. I still owe the the thermostat bellows photo on that, and I have not forgotton. I am planning to test your theory by taking a before picture then cutting the capillary carefully with a hacksaw to see if it expands further. I will do so as soon as I get my workbench set-up. Honorable Samurai Appliance repairman, thank-you for promoting your humble apprentice. Thanks for the Kudos guys. I have recently been doing a lot of research into water filtration/softening. If the Samurai thinks it would be of value, I could kick-off a thread on that subject. Purity of Essence!  |
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Samurai Appliance Repair Man Fermented Grand Master of Appliantology
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The Seven wrote: Thanks very much for your very sarcastic enlightenment and extreme analytical and unbiased explanations. I think the Iceman's analysis was written in a humorous tone to be sure; not sure I'd characterize it as sarcastic, though. |
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The Seven Master Appliantologist
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Exalted Grand Master Sumurai and Master Iceman, Excuse for my poor use of vocabulary. I am learning and will be "humorous" next time. The Seven. |
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sawdust123 Apprentice Appliantologist, First Class
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Iceman, Thanks for the warning. I was in a conversation the other day where this reared its head. Did you happen to trace the inverter circuit to see which device let the smoke escape? Inverter technology is used all over now from audio amplifiers to gas generators. They generally work by converting the AC to DC using a bridge rectifier on the input. Then they use some MOSFETs to chop the DC at a very high frequency to create a square wave. This is then fed to a transformer to step up the voltage as needed to run whatever it is that they need to run. The weight savings comes because the transformer is operating at a high frequency. A 60 Hz transformer needs to be large to avoid saturation in the iron core. At 60 KHz (or whatever higher frequency is being used) the transformer can shrink greatly while avoiding saturation. Problems sometimes arise because you are dealing with square waves, not sine waves. This is particularly true with compressor motors. You should never run an air conditioner off an inverter/generator that doesn't have a pure sine wave converter on it. |
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iceman Master Appliantologist
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Hi Sawdust123, I can see from reading your post that you are very wise in the ways of transformer size reduction, and understand that higher frequencies are a friend of the power designer. Regrettably they are a curse to the rest of us. In fact, I was just suppressing some unpleasant thoughts about conducted emissions on a current project when I came across your excellent tutorial. May I be the first to compliment you on your succinct summary of the essence of inverter design, not to mention the very appropriate warning about not using a square peg in a round hole (pardon my metaphor). I would also add that anything that has low frequency magnetics (e.g. 60Hz transformers) do not like square waves, although you can get away with it on small power cubes if you keep them cool, and if the inverter doesn't choke (current limit) on the unexpected heavy load. Regarding your question, my best guess is the FETs failed. Typically this is caused by excess heating in the devices, which happens if the snubber circuit fails to do it's job. The snubber fails when either the diode or the cap give up. This thing that really bugs me about this is the design problem is probably very easy to fix. Something simple like "wrong PIV on the snubber diode" or equally trivial. However, if you don't look at your warranty center return data, you will never know that you have a problem, much less how to fix it. I was hoping that the provocation directed towards Panasonic (Matsushita) in the invective above would stimulate a sentient response. Perhaps if I was a bit more explicit. PANASONIC MICROWAVE DESIGN CENTER: I have a smoking example of what is wrong with your product in my garage. Send me your FedEx account number and authorization to ship, and it is yours. Last edited on Mon Dec 5th, 2005 05:35 pm by iceman |
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hootmahn Grasshopper
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Ahso, I too have just experienced the enlightenment that the inverter board brings. My Kenmore Elite microwave oven brought me to this state after less than 2.5 years of ownership. It welcomed me into a new level of consciousness with the message "F-9." Unfortunately, the Sears repairman was not familiar with this message, but ah, I had discovered it on a little piece of paper hidden inside the control panel. The fact that he could not interpret "F-9" caused me some concern. But lo, he could call a technical help desk that only Sears Samurais may call and they explained to him the meaning of this message. My worst fears were realized when he said to me what the little piece of paper had already told me... replace the inverter board. Total cost of the experience, he said, would be $290, which, I believe is more than half the price of my 2-year-old microwave. I was dismayed, to say the least. This was just yesterday, and I am still adjusting to the out-of-body experience that followed. What must one do? The Sears Samurai left with $65 and I have 30 days to decide whether I want to contribute $225 more to complete my journey. The phrase "built-in obsolescence" keeps coming to my consciousness, as does the phrase "rip-off." But I may take another path. With a brother and sister-in-law in the appliance business, I may make a pilgrimage to their doorstep. The Humble Hootmahn |
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iceman Master Appliantologist
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Hi HM. I see that we share the same frustration. Consider this, I had mine repaired by Sears, and then failed again ~2 years later. Fool me once... Last edited on Sat Feb 18th, 2006 06:01 pm by iceman |
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hootmahn Grasshopper
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That's what I didn't want to do... have it repaired and then see it fry again in a year or two. My brother, who manages an appliance store, recommended I buy a less expensive model (hopefully without the dreaded inverter) since we usually use the microwave just to heat things up and cook simple dishes. That's what we plan to do, when we can afford to replace it. |
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iceman Master Appliantologist
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Cool HM. I recommend that you go with a brand name, not a Wal-Mart special. Two reasons: 1) Better a small Microwave that lasts, than a medium size one that doesn't. 2) Most people only want to cook the stuff on the inside of the oven. Hey Moostafa, you got that new fangled ELECT-TRI-CITY in your village yet? How do you guys heat stuff up quickly over there? iceman |
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skredberry Grasshopper
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I have an over the range NN-H264 that was bought in August 2004. Already had to replace a turntable motor on it, under warranty, because the thing made an atrocious grinding noise. Took about 3 months just to get the part. Now, by the postings below, I'm guessing I have an inverter issue again. I used the thing to thaw 2.5 lbs of food earlier. I had come back and the time was missing from the LED. Reset the time. Went back about 2hrs later or so and put it on for 1min 45 to heat some water and it died completely. Checked the breaker, good. Checked the outlet with an electric hand mixer, good. Unplugged for a while, plugged back in, nothing. Given the experience you've had with inverter boards and such, is it worth getting this monster fixed? Given that I paid $278 for 1.5yrs of use, I am trying to weigh as to whether this is even worth the service call. If it's more than a fuse and it's an inverter board issue, I'm guessing I'm out at least $150 for repairs. In checking websites for this issue, I certainly wished I'd known before my purchase. My last Panasonic lasted 12 years, but that was before the inverter turbo defrost was available. It still has a 5yr warranty on the tube, but given some of the feedbacks I've been coming across, this probably has nothing to do with the tube. Any thoughts or advice would be helpful, O wise one. |
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iceman Master Appliantologist
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Hi Skred. I suppose it comes down to the warranty, and if you think Panasonic has got it right yet. It is a good question. HELLO, HELLO OUT THERE! DOES ANYONE HAVE A PANASONIC INVERTER MICROWAVE OVEN THAT HAS LASTED LONGER THAN FIVE YEARS? If so, we would greatly appreciate to know how long it has lasted and what if any repairs have been made on it and if the repairs were not made under warranty, how much they cost. Personally, I plan to AVOID PANASONIC INVERTER microwave ovens, in consideration of the experiences described in this forum. Your mileage may vary. |
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skredberry Grasshopper
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I actually ended up getting the GE spacemaker 1.8cu ft as a replacement. It has most of the bells and whistles the Panasonic did but I couldn't get one without a handle on the door. I ended up paying more for this one than I did for the Panasonic, but thus far, it has a quieter operation, still has the defrost features and "quick" buttons, like beverages and such, but the cooking cavity seems bigger. (it probably is since it holds 2 racks, meaning 3 layers of foods) The scavengers from the garbage company have probably taken away the Panasonic thinking some dumb homeowners threw this thing away b/c they don't know how to fix it. I was told it was probably either the power supply or the inverter board. If it was the power supply, it would have been ok to replace, if it was the inverter board, it was a LOT more expensive. For $60 to have someone come out, then another $50-$150 depending on what the issue was, it wasn't worth investing for a $275 micro. The forum here helped since I at least knew the inverters were prone parts. Made the replacement decision much easier. |
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iceman Master Appliantologist
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Hi Skred, Good to hear. Care to try a Haiku? The rules are simple: 5 syllables 7 syllables 5 syllables The last one should contain some Satori (illumination/discovery/epiphany) Go for it! |
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Rob Stercraw Grasshopper
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Konichiwa samurai! I just joined the fun of inverter technology. Sears repairman just left after delivering me a $356 estimate to replace the inverter board in my barely 2 year old Kenmore Elite. I declined the repair, gave him $65 and now have a hefty paperweight. Can someone recommend a low-cost non-inverter equipped microhood? |
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iceman Master Appliantologist
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Hey everybody! I notice that Sears is taking a lot of people's $65 just to tell them it would be cheaper for them to replace their Microwave. Here are some handy tips: 1) Sears has a warranty return depot in every major city. Unless your Sears purchase is bolted down, call them to see if the diagnostic is less expensive if you bring it to them. 2) Most appliances have a cheat-sheet hidden in some relatively easy to find location on the appliance itself. If your appliance has error codes, this sheet will reveal how to get it to report them and how to interpret them. 3) Some small appliances are just not worth repairing. Say anything that costs under $150. Microwaves are right on the borderline, because the repair cost is often in excess of $150. 4) A quality microwave oven need not be expensive. Check out Consumer Reports magazine at your local library or get the ratings online, in exchange for money naturally. 5) Here is a FREE article on the subject: http://www.consumerreports.org/cro/appliances/microwave-ovens/reports/how-to-choose.htm?resultPageIndex=1&resultIndex=1&searchTerm=microwaves 6) Shop around. A microwave manufactured offshore probably costs less than $55.00 to manufacture and land on US soil. If you are paying more than $150 for a top of the line model, chances are you have not done enough legwork. Also microwaves are now sold by consumer electronics stores which are fiercely competitive and harbor strong animosity towards each other. Use this to your advantage. Nothing motivates a Fry's manger better than "The guy at Best-Buy said you guys couldn’t touch this price, and dared me to leave his store" Last edited on Sat May 6th, 2006 02:36 pm by iceman |
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Rob Stercraw Grasshopper
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Greetings Iceman! iceman wrote: Hey everybody! No could do. I tried that as the diagnostic for carry-in is $39. They told me they could not accept it there as microhoods were too large for the shipping containers they use to send them to the repair center.
I was not aware of this, but I saw the repairman found it. My unit did not have any error codes, it was completely dead.
This unit retailed at $599. Now, I never would have bought a six hundred dollar microwave on my own - I bought it at their outlet store for $249.
Here I appear to be kind of stuck. This microwave hood is a 36" model. Very few are 36" wide, the overwhelming majority are 30". Least expensive 36" unit is about $600. Unless I want to run a 30" microwave and utilize a "filler kit" to take up the excess space. If I do that, I'm still going to be spending about $300 by the time I get a unit and kit. Might be time to rethink this whole microhood situation. I know that if I do decide to buy another inverter-equipped microhood so I can fit the space I DEFINITELY will spring for the $60 extended warranty. Last edited on Wed May 24th, 2006 04:22 pm by Rob Stercraw |
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Rob Stercraw Grasshopper
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Well, I solved my problem, albeit in an odd manner. After getting the shocking estimate from the repairman, I went off in search of a new inverter board. Did find it on Sears' parts site for $176 ($50 cheaper than the repairman quoted me). Still a little hesitant to spend $200 on an appliance I only paid $249 for in the first place so I decided to go looking on ebay for it since I now had the part number. Didn't find the part, but I did find the same microwave, brand new in the box (but in "bisque" instead of black like mine) ending in less than an hour and the bidding was only at $18 (+$75 shipping). Wound up winning it for $51 ($126 including shipping) which was probably because the seller had a horrible picture and a really vague description. It arrived and I cautiously opened the box, expecting it to be heavily damaged or something... The vent adapter packed in the top of the carton was bent all to heck - looked like something got dropped on the carton.  Oh well, at least I can salvage the inverter board... Pull off the top styrofoam and what do you know, it's in PERFECT condition.  I guess someone opened the carton, saw the adapter all crunched and wrote the thing off. It had never been out of the carton.Plugged it in to test and it worked fine! YES!!!  Stripped the old black one down so I could swap the color keyed pieces to the new unit and decided to strip the good PC boards, magnetron and turntable motor out of the old one to keep as spares. Got to the inverter board and found it had burned and started to melt the surrounding plastic. Swapped the plastics to the new unit (decided to keep the bisque stuff as wife is talking about redoing the kitchen). The only electrical connection I had to undo was the door. Retested it after assembly and all is still well. Now I have tons of spares and a working unit again! Yes, I know that probably wasnt a factory authorized procedure, but it worked. If I wouldnt have lucked into the cheap parts, I probably would have thrown it away. |
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iceman Master Appliantologist
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Rob, Outstanding! Samurai, I think a significant promotion is in order here, don't you? |
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grindit Grasshopper
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Hi Iceman- Read your post with interest as I do have a countertop Panasonic Inverter Microwave Model NN-S760WA that I bought in late 2000. It just died this week, so yes, it did last over 5 years. It will turn on briefly but shut off after a 4-5 seconds, not enough to heat anything. I checked the interlock switches and they are OK, but that's about as far as I got. It was a nice unit while it lasted. Not knowing much about Inverter ovens, any diagnostic suggestions while I have the patient open prior to sending it to microwave heaven? |
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Biannale Grasshopper
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 Not so lucky (or erudite) as you, I have already disposed of the over the range GE XL1800 (circa 2000) with the broken door spring, repair estimate near $280. So, what is the best replacement for me? Previously we cut out an over the range cabinet and (oh can you say fire hazard?) just placed the unit on the cut out. Now I want a real install. I have 39" available, a top vent, and my 120 all ready. Really want a good ven fan. Suggestions? Model number? Many thanks. |
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VXO Buckaroo Banzai Appliantologist
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What... no haiku for this thread yet? Well then... behold: Inverter Power I had an Inverter microwave, which died a horrible death due to low line voltage. I was heating something up in it and didn't notice that our illustrious local electric monopoly, FPL, apparently thought the Magic Voltage for the day should be 80... the cooling fan stalled and the inverter and magnetron cooked. |
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Keinokuorma Fellow, Academy of Sublime Masters of Appliantology 
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Hard disk drive magnets make similarly insane beer box magnets, but if you clunk one onto the fridge, you'll probably have to slide it to the edge to get it off. (Watch your fingers - pinch hazards exist with these...) True, stepper servo magnets are really strong. Must give high torque with little electric power. So far managed to ruin a watch and cell phone, and pinch a nice 4 cm tear on my palm. |
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iceman Master Appliantologist
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Hey VXO, Excellent Haiku. Domo.  iceman |
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iceman Master Appliantologist
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Well, my venerable Jenn-air Microwave has given up the ghost after 16 years of faithful service (Model M167W June 1992). So I went on Sears.ca to check out the current offerings. Looks like some people never learn. Most notably Panasonic product developers, and some unfortunate Sears customers. Here is the current crop of customer reviews for the Panasonic Model NNH965W or Sears Canada model number 223 619 298 on sears.ca. Since the recycle charge is $39.00 anyways, why not use that money to ship the defective microwave back to Panasonic Canada instead, and put a note inside to let them know what you really think? The address is: Panasonic Canada Inc 5770 Ambler Dr, Mississauga, ON L4W 2T3 (905) 238-2296 or Panasonic Canada Inc 12-2135 32 Avenue NE, Calgary, AB T2E 6Z3 (403) 769-6700 or Panasonic Canada Inc 12111 Riverside Way, Richmond, BC V6W 1K8 (604) 278-4211 or for our colleagues in La Belle Provence: Panasonic Canada Inc 3075 Louis A Amos, Lachine, QC H8T 1C4 (514) 633-8684 "Je me Souviens" Panasonic: What a KEYSTONE-COP CLOWN SHOW! Sears Canada: Customer Reviews Average Customer Review:   Our second one in 2 years just caught fire!Reviewer: JON from Marmora, Ontario We have owned two of this model of Panasonic oven. After the first one blew oup 2 years ago, we figured we had bought a lemon, and Sears very nicely replaced it with apologies. Now this one just started smoking and would not run: it is now in the backyard because I didn't want the smoke alarms to go off. Wonderful big microwave, and we need a big one. But WHAT A PIECE OF GARBAGE this model is! Panasonic should be ashamed. Piece of JunkReviewer: from Had this for a year as well. Magnetron blew causing the inside to burn. Under warranty yes for magnetron but the labor is as much as a new unit. Stay away from panasonic microwaves. Not even worth one star as well Do Not Purchase This MicrowaveReviewer: from My husband I bought this with all of our saved up gift cards and within eight months it had a burnt out fuse. 45 days after the 2 year warranty expired the magnatron blew up. We were charged $39.95 to be told the magnatron blew up then quoted another $198 plus tax to fix. Then another $39 to dispose of it. It is a lemon and not worth even one star. |
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grey shrek Sublime Master of Appliantology 
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Changed too many of those boards in my long ago Sears days , never bought one ..Cheep G.E. with no bells will do just fine . Only want hot food and hot coffee as required... |
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Goosegog Senior Apprentice Appliantologist 
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Yes, as a matter of fact I have a NNT790SC which entered my world Sep 14, 2002, which makes it 5 years, 7 months and 6 days old. BUT... A couple of weeks ago it lost some virility. I'd guess it is producing about 50% of normal power. And two or three times it has turned itself off a few seconds after starting. Also, it has a touch of droop. The top hinge has play in it and the door, when closed, is slightly raised at the right end. This renders the door open button ineffective unless one pushes the door down before pushing the button. I think we are stuck with replacing like with like, because it is stainless and built into the cabinetry with a Panasonic stainless trim kit, steel tray and venting kit that I hope still fits a current Pana. I do not feel like buying another kit. |
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iceman Master Appliantologist
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Hi Grey Shrek, Thanks for confirming the worst-case scenario. I agree with you, I bought a GE. Don't tell Moostafa. I just needed a countertop with a trim kit, and once you rule out Panasonic, very few large countertops fit the bill. Hi Goosegog, Don't do it man! If you don't believe me, and Grey Shrek, read the litany of comments on this web page: http://www.associatedcontent.com/article/3765/panasonic_12_cu_ft_inverter_microwave.html Also, the Sears salesman just told me that Sears will no longer offer the "Extended Warranty Plan" for counter top microwaves. Finally, check out the warranty on the top-of-the-line stainless Panasonic from Sears.ca. Model 223 619 073 for $379.99: One year! Why do you think that is? Heck I would rather ignore the sacred pearls of the Samurai: "General appliance rule of thumb: Avoid GE like the West Nile Virus. If you read Consumer Reports and they recommend a GE product, crumple up that page and use it for toilet paper 'cause that's all it's worth. Despite horrendous quality problems, outrageous markups on repair parts, and a damn-near universal agreement among appliance servicers that today's GE appliances SUCK out loud, people keep buying GE and so the freak show continues. Ok, with that out the way..." (Found in http://fixitnow.com/2003/09/mailbag-appliance-brand.htm) than buy a Panasonic Inverter Microwave! Last edited on Tue Apr 22nd, 2008 12:09 am by iceman |
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Goosegog Senior Apprentice Appliantologist
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Thanks for the response, Iceman. I take it to heart, especially as the salesman at Future Shop told me they take a lot of Panas back for warranty repair. But really, for $100-200 isn't all this stuff going to be crap? Anyway I took the thing apart and fixed the droop. The top hinge was bent, that was it. I had a good look inside for burnt connections or evidence of heat and found nothing. It is very clean. I removed and cleaned the ribbon cable connection to the controller board and reseated all other connections. We'll see if it makes any difference. Re the cabinet kit: I have to stick with the same H x W opening or buy a new kit, and they are expensive (about the same cost as a mid-size microwave in fact.) The air duct part is sheet metal that guides cool air in through the front grille into slots on the left side. The air gets blown out the back by the fan and finds its way out through the rest off the grille. Not being a sheet metal worker I probably could not fabricate something for a different style of oven even if the front dimensions fit. But it's tempting. |
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iceman Master Appliantologist
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Hi Goosegog, I wonder if the new ones just vent out a slot by the door. My old Jenn-air did that. I am about to find out, becuase I bought one and a trim kit to go with it. Sorry, they don't come in Stainless. Sears 223 619 472 GE PEBB206CDN And yes, the trim kits are pricey. |
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Goosegog Senior Apprentice Appliantologist
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Iceman, Pana's website shows what models (old and new) the various trim kits fit. There are two current stainless models that fit the 30" kit that I have. Big Rock? I can guess where you are! Last edited on Tue Apr 22nd, 2008 04:17 am by Goosegog |
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iceman Master Appliantologist
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Hi GG, OK, good luck with that dude. BTW I used to drink XOS made with water fresh out of Cleveland Dam. But that was a long time, and a continetal divide ago. |
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jwj2357 Senior Apprentice Appliantologist
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friend has one that slows and makes noise, told it is probably the magnetron, going to check that. not getting very good info on these. ive had microwaves stop working but normally its a melted connector on the magnetron. this model is a nn-h665bf inverter written on outside of mocrowave. ughhh! bugs me that a company would find this acceptable. another thing is how do they sell a microwave for under 200 bucks then it dies and you need say a transformer that sells for 300. |
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iceman Master Appliantologist
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Marketing is slick Product fire in the market Keep on selling it! |
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iceman Master Appliantologist
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un·re·pent·ant (  n r -p n t nt) adj. Having or exhibiting no remorse. |
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RegUS_PatOff Fellow, Academy of Sublime Masters of Appliantology 
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King Gillette: "Free Razor" (buy our replacement blades) Free cell phone ... Free lunch ... etc ... |
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Konnan Merit Apprentice Appliantologist
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grindit wrote:Hi Iceman- Hi Master iceman, God of the mighty Panasonic Inverter Microwave, could you help me ? I have exactly the same problem as the guy I quoted above. Microwave will work for a few seconds at a time at most. It was slightly arcing due to excess grease, because of the bad integrated hood fan design, grease manage to get inside the microwave electronics. Managed to fix the arcing problem with a good cleaning, but obviously something is damaged. The high voltage power diode looks to be burnt, due to blackened PCB in the area... I wonder why it still works for a few seconds on the other hand... could it be only a fan problem then the microwave enter in protection mode ? Diode is UX-C2B made by SANKEN Electric, now discontinued part worth 30$ on eBay with no SANKEN Electric equivalence, but a local store can supply an equivalent from another brand for 5$. Should I also look at the high voltage capacitor or somewhere else ? Thanks alot Master iceman, If anyone else wants to help me, I'm all ears. Thanks ! Konnan Last edited on Sun Nov 8th, 2009 10:25 am by Konnan |
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iceman Master Appliantologist
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Hi Konnan, To quote our erudite leader "Never replace a part unless you have proof that the part is bad." http://fixitnow.com/wp/2005/09/23/samurais-12-laws-of-appliance-repair/ Let us consider. You have used a special tool to remove tamper proof fasteners to gain access to the POWER Printed circuit board of a device designed to emit MICROWAVES. Presumably you read the prominent safety warnings on the unit as you did so. Suppose that you did manage to replace enough parts to make it work. Lets postulate some follow-on questions: 1) Was the arcing caused by grease or by the normal failure mode of this product? 2) How long will it work for before it fails again? 3) Are you comfortable being near this device while it is operating under your fresh repair? How about your kids? 4) Could your repair result is a fire when you are not at home? OK, let's assume that you have decided to disregard the cautions above and are prepared to assume full responsibility of the consequences of your repair or losses resulting therefrom. Here are the logical steps the I would follow if I had decided not to just replace the unit. 1) Try to obtain a schematic of the power converter board. 2) Failing that, write down all the part numbers of the power devices (FETs, Diodes, BJTs). The really damaged ones might be illegible 3) Get the data sheets for the defective devices. 4) De-solder all power devices and test them. 5) Replace the defective ones. Once again, I STRONGLY recommend that you dispose of this microwave and go get a new one. That is what I did, and I am very satisfied with it. This project has exponentially diminishing returns. Oh, and don't forget the flip Panasonic the bird. |
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Goosegog Senior Apprentice Appliantologist
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Further to my post of April 21 2008 we have finally got fed up with a microwave that only operates for 23 seconds at 1/3 power. Because of the vent and trim kit issue I have purloined another Pana (NNT795S - CAN$220 at London Drugs) which seems to be the only one that fits. It's been there 3 days and still works, so it looks very promising. Interestingly, it's almost impossible to fit the existing vent kit sheet metal to the new unit, as Pana has changed the security screws on the back from a "star" pattern to a "star-with-a-projecting-prong-in-the-middle" pattern, for which I do not have the proper tool. Vice-grips rule! It's only one screw, so I hope this will not invalidate the warranty. |
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Konnan Merit Apprentice Appliantologist
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iceman wrote:1) Was the arcing caused by grease or by the normal failure mode of this product? Thank you for this nice reply, iceman, Master of the Panasonic ! Thank you for the link to the 12 laws... should have read that before hehe ! 1) Well, removing grease removed arcing between power board and a ground screw when the microwave is working, but yes I guess it's just delaying its death a few more years... 1) Getting a schematic for an inverter power board from a discontinued Panasonic microwave ? Pretty much impossible, isn't it ? You have many valid points, but these damn large microwaves with integrated hood fan vents are several hundred $$$ expensive... so I may want to try replace that 5$ diode... I will not play with the magnetron or waveguide, don't worry, be happy ! As you said, if that doesn't work, it will be lost time, lost money and a lost cause, so I need to further think about it. That diode is probably not the only damaged part. Agreed on the "flip the bird" part... ;-) Thank you again for your insight ! Konnan |
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iceman Master Appliantologist
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Hi GG, They sell those kind of Screwdrivers at Princess auto in a set of 6 for cheap. Part 2920902. http://www.princessauto.com/tools/hand-tools/torx-keys/2920902-6-pc-torx-screwdriver-set I got 'em for $6.99 on sale. Which they frequently are. Hi Konnan, Earlier in this thread Rob Stercraw solved your problem a little bit more safely. Please consider his solution. He got another power board. Otherwise: Broke the secret screw Found the power board and fixed One kid has three eyes! Last edited on Sun Nov 8th, 2009 09:49 pm by iceman |
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Konnan Merit Apprentice Appliantologist
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Hi Mr. iceman, You are again right, but I believe those power boards are not an easy find. I will try to look on eBay unless you know a better place... we never know. Thanks again ! Konnan |
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RegUS_PatOff Fellow, Academy of Sublime Masters of Appliantology
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Microwave model number ? |
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Konnan Merit Apprentice Appliantologist
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Hello RegUS_PatOff Sorry for the huge delay... It's : NNH264W EDIT : I think the W is only for color white, so number is really NNH264 or NN-H264 which is similar to NN-S254 if I looked carefully... sorry ! Thank you very much, Konnan Last edited on Thu Nov 19th, 2009 09:05 pm by Konnan |
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RegUS_PatOff Fellow, Academy of Sublime Masters of Appliantology
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"Run away !" from this thread http://applianceguru.com/forum1/21915-1.html RegUS_PatOff wrote:
http://www.mediafire.com/file/zf3ymc2tmdm/panasonic_inverters.pdf |
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Konnan Merit Apprentice Appliantologist
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You are making me sad !  |
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