Panasonic microwave, blown inverter board transformer

OK. On the one hand:

Purchase new Board: US$25 + shipping Install New Board: 2 hours work

It all works: All good!

Magnetron is bad: Purchase new Magnetron for US$65 + shipping Install new Magnetron: 2 hours work.

It wall works: 4 hours + US$90 + shipping.

On the other hand, a brand new 1,000 watt microwave: US$150, complete with warranty.

I admire your wish to reduce landfill, but I have to wonder at the investment in a 10 year old device that is heavily used by your own description.

Peter Wieck Melrose Park, PA

Farberware Classic 1.1 cu. ft .1000-Watt Microwave Oven $99.99 Farberware Classic 0.9 cu. ft. 900-Watt Microwave Oven $89.99

Thanks. I would feel sad if I hadn't made an attempt. A new one would be a bit more expensive though because it's an oven and grill combi. Hate that it seems so simple to fix if only I could find the correct board to plug in :(

Andrew

1 (800) 211-7262

I entirely understand that this Group exists so that individuals may discus s means-and-methods for doing pretty much anything at all in the hardest po ssible way, reaching for the least satisfactory results. And that includes reaching around the world for S.W.A.G., anecdotal experiences and arbitrary suggestions.

Rather than going to the Mother Ship and asking there.

Panasonic Customer Service number above.

Then:

|ga|27|Tech-CE-SQR-Search-BMM|CE-Panasonic|&JPKW=%2Bpanasonic%20%2Bengland&JPDC=S&JPST=&JPAD=378934176681&JPMT=b&JPNW=g&JPAF=txt&JPRC=1&JPCD=&JPOP=&cmpid=2032112328&agid=76054807163&fiid=&tgtid=kwd-807471796533&ntw=g&dvc=c&gclid=CjwKCAjw5vz2BRAtEiwAbcVIL4IpznzJVHkSJM0UAa4rerYc42_ibvjnkdsd_EkpKG39BsihtcQHsBoC1VcQAvD_BwE

Peter Wieck Melrose Park, PA

"JustAnswer LLC is in no way associated with Panasonic. All other brands and trademarks are the property of their respective owners who in no way endorse JustAnswer LLC."

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Adrian C

Doesn't change the fact that it is a source for information. Further, it suggests that it is geared towards older equipment.

Peter Wieck Melrose Park, PA

Thanks :)

Andrew

What is the reliability difference, if any between the classic transfomer/diode/capacitors and the fancy inverter ovens?

The Inverter model reliably makes a louder sound on expiry?

I'd bet the fancy Inverter design is to get the price down, cost of copper and weight etc. The chief reason for a SMPS.

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Adrian C

It is all in accordance with what you want.

An "inverter" microwave modulates the output of the magnetron directly. So, 50% setting means the magnetron is putting out 50% of its full capacity, b ut all of the time. With a conventional microwave, that is achieved by runn ing the magnetron in duty/rest cycles. 100% for 50% of the time 0% for 50% of the time. Inverter-based microwaves become far more flexible and therefo re far more useful.

Re Reliability: Our present Panasonic (inverter) is about 6 years old and g ets moderate use. It replaced a 16 year old multi-voltage BEAC we purchased in Saudi, that is now still in minimal use by a neighbor in his garage wor kshop. We keep our devices clean, make sure they get enough air circulation , and, heaven forfend, even clean the vents regularly!

Basic care-and-feeding is becoming a lost art.

Peter Wieck Melrose Park, PA

The question is, how long would these MWs last under the same usage as the original Panasonic? I suspect perhaps 5 years...so repairing a machine that lasted 10 years, might cost $100 - and give it another ten years. Vs. replacing it with a cheaper design that may last 1/2 the time? Is that really a better deal? Plus you have saved landfill.

John :-#)#

Impressive. I know how you feel: That's what happened when I cooked a yam (potatoe) for 16 minutes instead of 6 minutes. It was glowing bright red inside just before I opened the door. The inside of my Panasonic NN-S533WF (Sensor 1300w) microwave oven changed from white to yam colored. I tried to clean it, but the yam color is permanently baked into the paint. The S/N label says made in 2003. I think I received it as a present in 2005, making it 15 years old. It works as well today as it did in 2005 with no change in output level. That's one of the benefits of an inverter oven.

Try measuring again with a much better ohmmeter or preferably an ESR meter, which will measure resistances below 1 ohm. The two terminals on the magottron are the filament wires. Less than 1 ohm is typical and is easily mistaken for a short circuit. "Magnetron Test for Opens, shorts or Insufficient Power" The instructions are for a commerical oven, which may have more than one magnetron inside, but the methods are the same for a home microwave oven with only one magnetron.

Near zero. I haven't repaired too many microwave ovens and only one inverter oven. Mostly, what I find are (in order of frequency):

1. Blown high voltage diodes.
2. Blown high voltage capacitor.
3. Blown thermal protection fuse.
4. Filthy and intermittent door interlock switch.
5. Low magentron output or dead magnetron. I would guess I've fixed about 20 mw ovens and have yet to see a blown high voltage transformer. If the enamel coating on the torroid are discoulored from overheating, you might have a problem with the transformer. If it looks normal, it's something else.

You might want to try searching on YouTube for videos on how to diagnose and repair microwave ovens. This looks like a good start:

What you're seeing are differences in part number because the manufacturer sourced their magnetron from multiple (Chinese) sources. Each source has a different part number, but are functionally and mechanically identical. The NN-A554W is a 1000 watt oven, so any 1000 watt magnetron that mechanically fits is likely to work.

No parts? Google is your friend: Hmmm... are you in the UK? The Panasonic model number seems to be a UK only 230VAC oven?

Well, if you want an exact replacement, it would helpful if you would supply the full model number. Is it NN-A554WB or NN-A554WF ?

If you have no clue what you're doing, and are lacking in basic test equipment, I would recommend:

1. Checking the magnetron with an ohms guesser.
2. If ok, replace the Hi-V diodes and Hi-V capacitor.
3. If that doesn't fix it, don't replace the magnetron. Instead by a replacement inverter board. It's one of these:
4. If that doesn't fix it, it MIGHT be the magnetron, but I doublt it. Magnetrons usually fade away slowly, where cooking takes longer and longer, until it doesn't cook. It does not die suddenly or belch fire. If you bought a replacement board, you've probably spend more on the repair than the oven is worth. I suggest you cut your losses and just buy a new oven.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

The longevity of any given appliance is a factor. But, in one's choice of a ppliances, longevity is only one (1) factor. If one looks at the life-cycle cost, the factors are:

a) Cost to produce, market, transport and sell. b) Cost of energy used over the life of the appliance (and, technically, th e source of that energy). c) Cost of disposal when 'used up'.

Then, there are wearing parts: hinges & latches, microwave safe internal fi nishes, bearings and so forth. Investing in repair parts might not give tha t further ten years.

So, if one assumes that the typical microwave lasts around ten years, and i s in actual use for (low end for this purpose) one full hour per week, that comes to 520 hours of operation. A magnetron tube is about 65% efficient t hese days. Assume all microwaves are a (mere) 700 watts. Assume the US nati onal average cost pr KWH of $0.1331. The equation looks like this:

((700/0.65) x 520)/1,000)=560. 560 x 0.1331 = 74.536. So, it will use $

74.54 in electricity in those 10 years at that rate. A modern inverter stan ds to use, on average, 50% less energy. So use $37 as the 'advantage' per t en years to the inverter technology.

I dunno... It has been my experience that modern microwaves are largely mad e of parts made by robots, assembled mostly by robots, tested by robots and (maybe) visually inspected and packed by a exceedingly bored human.

Chances for human error are minuscule. Finishes are far better. Parts varia bility is far less. And so on. As cheaply made and looking as these things might feel, with proper care and feeding, there is no reason why that $89 d ollar device might not last that 10 years and beyond.

Fully agreed on the landfill - we are privileged that most scrap metal from our township is recycled to Acelor Mittal:

Which has been in continuous, uninterrupted operation (including wars, depressio ns, holidays and so forth) since 1810.

It is a process.

Peter Wieck Melrose Park, PA

We have a National (Panasonic) microwave from 1981, still working a treat. I know of others like it. It's pretty hard to compare MTBF when you have zero F.

well, panasonic does make a decent microwave oven, so this is probably the cadillac of anything with an inverter in it. I have a hand me down inverter panasonic. Seems to work fine, I just use the quick minute button for anything but defrosting stuff. I still have no idea what a baked potato button is supposed to do or why I'd want a power level of 2/10 or anything goofy like that. My favorite interface was on the Tappan ovens with a timer with two timing ranges, a cook/defrost switch and start and stop buttons. The design was pure genius, and hasn't been surpassed to this day. I also keep a 1981 samsung microwave in the museum. It has a whopping 20 screws just to keep the plastic window and shield in the door. No way any part on a $89 medea special will mechanically outlast this thing.

I do the open up and deep clean and oil fan bearings every so many years, but this is not something a normal consumer could or should do. BWT, the fans in modern robo-build microwaves are truly puny garbage. I bent she shaft of one just trying to remove the fan blades. No joke. They're really engineered the quality out of these things.

Lol, I've wondered about the "sensor" in these things. I know can't be related to any sort of device that measures anything. Must be marketing speak or a weirdly translated word.

I'd follow these steps too, but I also have the test equipment for doing so, but OP says they have an inverter microwave. That should scratch the #2s off the list, which is really easy for for a traditional half-doubler microwave oven. They have no way to test the HV section safely. Microwaves are truly the most dangerous electronic appliances to play with.

I don't think the "sensor" is a gimmick.

From what I ran across somewhere, it's like a humidity or moisture measurement and really did/does work. I just had a 16~17 year old GE over-the-range type that went out that used sensor cooking and now using a $99 counter top model (1250W Magic Chef) that doesn't, I miss it.

I would of replaced the GE with a current model but it's a 2 man job and with ye old pandemic, I figured the $99 special will suffice for now until an assistant is found. What's odd with the break down is the keypad doesn't work and it's not the keypad or ribbon cable.

About a month before I noticed the 3-6-9 buttons wouldn't do anything but all the others were fine. Then one early morning, ComEd (local power company) cut the power for about 10 minutes which reset the clock back to the blinking 12 (actually I think it scrolls "Press clock to set time") and that was that. No more workie. It does boot, plug it in, you get the beep and even the "GE brings great things to life" scrolls on the display.

Everywhere I checked for parts (figured a new/used control panel) ended up the same "Not in stock - No Longer Available".

Disappointing.

-bruce snipped-for-privacy@ripco.com

It's a humidity sensor. When whatever you're cooking gets hot enough to vaporize water, the "sensor" detects the water vapor and shuts off the oven, usually after a short delay. The alleged advantage is that you don't need to enter the cooking time or power level, but you do need to enter the type of food: I've only used the sensor feature a few times. No opinion on whether it's useful, or yet another useless feature.

If you don't know what you're doing, don't have sufficient experience, can't follow advice, and are afraid of high voltage, perhaps you really shouldn't be fixing microwave ovens?

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Say there is a moisture detector in ther sniffing the air being pulled from the cavity. It doesn't prevent a frozen pot pie from burning, it doesn't prevent anything from overcooking. It doesn't seem to know when a frozen sausage is transitioning from thawing to outright cooking. I really have no idea what it's doing. It's too mysterious to take seriously. Really old microwaves sometimes had the temperature probe- that made sense, assuming you were into cooking a turkey in the microwave oven for

30 minutes.

Say it's real. Do the just modulate the cooing duty cycle? It doesn't seem to speed up or slow anything down, ot at least I've not found a mode that isn's still time based.

What were the delicious things you could pull off with the sensor as sous chef that just don't work with the magic chef?

Any parted out ones on ebay? No real need for "new" as long as it works.

I was approached with a friend asking how to fix their above range microwave oven too. I want to help, but until they can read me the model # off the door, I can't do much with suggestions on what the next move is.