Magnetron question

So the reason microwave ovens cycle on and off at the lower power settings is because different caps would be needed for different power outputs? I always thought it was the tube itself, that it worked best at some certain power output. Eric

Reply to
etpm
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I haven't heard a convincing argument that the magnetron is the problem. How did you verify that?

Reply to
Mike

Early 2 power level nukes used a capacitor & HV switch to reduce anode i. It's cheaper & more reliable to switch the power on & off. And safer. The only time it matters is with mousse.

NT

Reply to
tabbypurr

Darn it! I was gonna try to make some mousse tonight in the microwave. Eric

Reply to
etpm

@Mike I have no hard evidence about the magnetron being faulty, however thi s was the diagnosis made by the tech guy who came over to fix it. The whirlpool oven displays error F05 (which I was not able to find anywher e in my research over the internet). It displays it only when using feature s that relay on microwawes, other than that it works fine. The "official repair guide" - which I have not seen - seems to state that t o fix error F05 it is needed to replace the inverter board and the magnetro n. Since the tech guy had a spare new inverter board, he switched it and left it in the oven, unfortunately that didn't fix the error. That's the reason why I am assuming it's the faulty magnetron.. I am actually hoping that, tr usting that the tech guy placed a working inverter board inside my oven. :)

Thank you for your inputs, you're being really helpful

Reply to
technowb

Shop for a second hand one of the same age/power range, and swap components.

Reply to
Sjouke Burry

Sometimes that is the only way to repair items. I do not like built in items for that reason. Or even fancey (expensive) items to do simple tasks. I really hate the cars that give you almost no options as to what you want. Last car had to have leather seats if I wanted a V6 engine. I hate the leather. Makes me sweat in the summer and cold in the winter before the heated seats warm up. Had the 'moon roof' no need at all for that as far as I am concerned.

About 10 years ago I bought a house and the only reasonable place for the refrigerator is a small opening. That ment I was limiated in the height and especially the width of a unit I could use unless modifications to the cabinet were made.

Reply to
Ralph Mowery

minute at full power, heating it for two minutes at half power(or even medium high or 60% if such setting available)? That way the magnetron cycles on and off instead of running constantly, and also the food is more evenly heated. "

No. It is doing the same work AND being thermally cycled. Now had you an ol der one where they put more than six bucks into it, they had a lower tap on the transformer for the lower power setting. One of those maybe. With that , lower power might just make the tube last longer. Not by cycling on and o ff for a longer time.

Reply to
jurb6006

It seems CRTs are. I had a Zenith 20" come in, had the best picture I ever saw on that model because the tube was strong. I mean STRONG. Te complaint was there was a slight noise when it was turned off. I discovered that it r eally wasn't turning off, when the micro said power off it muted the audio and video but the HV, and of course the filament of the CRT and all that wa s still on. I told them not to fix it. Management didn't agree so it got fi xed.

We knew for a long time about CRTs, like NEC bigscreens had active all the time AKB and when you first turned them on they were actually "cathode stri pping". Sony's AKB had a delay until beam current was normalized, as told b y the AKB circuit. Didn't help, their CRTs were junk by then. But I got thi s 35 year old Sony in my room with about the best god damn picture you ever saw, and it is never shut off. To shut it up I just switch to a dead sourc e. You will NOT see color like on this thing.

Anyway, the magnetron has a filament so when it cycles on and off the filam ent thermally cycles and in almost ANYTHING in the physical world thermal c ycling is bad.

The old microwaves with the tap, the filament voltage was still the same.

Actually if you look at the power level switch on one of them you can see i t is made to switch a few thousand volts. It is not a simple slide switch.

Reply to
jurb6006

For my GE micro, power level cycling is as follows:

HI/Full - Magnetron on continuously

90% - On 27sec, off 3sec 80% - On 24sec, off 6sec. etc etc. 50%/Medium - On 15sec, off 15sec 20%/Lowish - On 6sec, off 24sec

And so on.

I'm sure the designers took everything into account when providing for all those power levels. I almost never use Full, except for when boiling water.

Reply to
thekmanrocks

Which of course, is entirely relevant to magnetrons.

--
"I am a river to my people." 
Jeff-1.0 
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Reply to
Fox's Mercantile

Try cooking an egg to dispel that thought. Older microwaves had minimum on-time because of the filament warm up time...and the lack of high voltage power supply electronics back then. A 10-second on-time is plenty of time for localized heating to cause food to explode. The newer inverter microwaves have much shorter on-times so food doesn't explode as easily even at the same average power.

Under what conditions did the microwave fail?

Did it quit while in use? Between uses? Any power outages or lightning storms in between?

I've never fixed a newer microwave. All my repairs were diode replacements in older machines. I don't think I'd even try to fix my Panasonic inverter without a full set of schematics. Even then, all the sensors would be a nightmare to reverse-engineer.

I'm gonna make some guesses. I doubt that the magnetron has failed. Sure, it can crack if you overheatd it by running it for long periods nearly empty.

More likely something else failed. There's not much to cause instant failure of a magnetron if you didn't overheat it. I doubt that there are any high voltage components on the controller that was replaced. The oven is full of sensors for safety and cook control. Any of them can cause the system to inhibit the microwave function. I'd guess that the only things a controller would monitor might be power supply voltage and temperature. Just not worth the expense to do more. But there's plenty more to go wrong.

Here's some reading material.

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Reply to
Mike

Thank you! I've read everything, and I searched for the exact magnetron; un fortunately I have to go for an "80% compatibile model" since everytime I f ind a website listing the correct model it's either out of stock or the web site fails under a 404 error.

I have one more question, since I noticed a difference between apparently t he same model by different manufacturers:

Does the shape of the hole of the "microwaves cannon" make some difference? I can't find one with the exact shape of my original model (square): the a vailable shapes of the alternatives are circle and triangle.. should I go f or one of those randomly or there are better chances of compatibility if I choose one over the other?

Thank you again

Reply to
technowb

Try

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Reply to
Look165

I dunno bout that. A magnetron has a cathode heating up with full plate vol tage applied which is known to cause damage to CRT cathodes. That's why Son ys with AKB had a turn on delay until the detected tickle current is up to a certain level. It lessens "cathode stripping". Well lessenED, no more CRT s, more useless knowledge.

Think you bad to the bone ? Got moxy, resources n shit ? Wana make some mon ey ?

Build a left handed microwave. Seriously, there is a market and some people really need them and NOBODY makes them. They all go the same way but not e verybody's kitchen goes the same way. Just look at your microwave in a mirr or and that is what could sell. You would have 100% of the market for maybe a couple of years.

Get your torches, MIG welders, die grinders, the usual implements of destru ction and get rich.

I actually looked into it, it is a big pain in the ass. And you only get a couple years because the big boys will start making them as soon as they de tect your presence in the market.

Now THAT's irrelevant...but true.

Reply to
jurb6006

I made that observation years ago -- and it still amuses me that that is still the case.

Jonesy

Reply to
Allodoxaphobia

Lefthanded microwaves:

I think I've seen a few lefthanded TV sets(CRT era)!

Where the tuning knob, volume, brighness, speaker are to the left of the picture tube.

Reply to
thekmanrocks

Hi guys, thank you all. I can confirm that in AMW842IX - that uses magnetron 2M236-M62 by default - we can use as an alternative magnetron 2M236-M42 by Panasonic. I am not su re if other brands of the same model works the same, however the oven is on duty again, and trying to repair it was worth the effort. :)

Thank you again

Reply to
technowb

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