Power supplies with solid polymer caps

I have read that electrolytic capacitors are the least reliable component in power supplies. I have also read that there are motherboards with solid polymer capacitors. Are there any power supplies with solid polymer capacitors? Thank you in advance for all replies.

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Reply to
Daniel Prince
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I've found pc coo;ing to be the most reliable supplier. Not always the cheapest, but highly reliable.

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Reply to
Pen

Try the usual places where experts test and disect PSUs (they actually remove all the power transistors and diodes), like:

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I don' t know if any PC PSUs use polymer/organic/os-con caps exclusively on the low voltage side (the only place they will be found, as polymers aren't made for more than about 30-50 volts). Polymers seem to be found mostly in PSUs with really high power ratings, but Seasonic makes a 650W with some in it.

More important than having polymers is not having junk brand caps because junk can fail in just 1-2 years, while good conventional electrolytics can last a decade, as demonstrated by my vintage 1999 Delta PSUs (only Japanese caps -- none bulging, and the few I sampled measured in specs for capacitance and ESR last year) and my 33-year- old TV (only 2 of its Sanyo caps failed, and I love the fake wood grain).

Reply to
larry moe 'n curly

If I interpret your question correctly, it's meaningless.

Polymer capacitors (ie, plastic-dielectric caps, such as polystryrene, Mylar, and Teflon) simply cannot produce the huge capacitances in small spaces that electrolytics can. They cannot easily replace electrolytics.

Reply to
William Sommerwerck

I think the OP is referring to claims such as these:

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*cough*
Reply to
JW

*cough", indeed.

65 degrees C is 149 degrees F. I doubt that the average computer gets much past 100 degrees. I'm also curious as to how they can get so much capacitance in such a small space using plastic dielectrics.

I've owned electronic equipment (that I bought myself) for 45 years. The /only/ piece of equipment that failed because of a bad electrolytic was a JVC hall synthesizer, which was manufactured with a run of bad caps. (I have two of these, and the second one also needs cap replacement, though I haven't gotten around to it.)

It's true that electrolytics are among the least reliable of components -- but they're not /that/ unreliable.

Reply to
William Sommerwerck

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Yeah they are. I've personally changed a couple thousand - 10x more than all other components combined - even mechanical wear out parts.

G=B2

Reply to
stratus46

Most of the stuff used now in retail products isn't anything close to the quality of the electrolytics by Spraque, Cornell-Dublier, Mallory, Nichicon, etc. Here's an analysis comparing the chemistry of some good Japanese caps to some bad Taiwanese ones:

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Here's a video card that wasn't much more than a year old when three of its caps (Sacon brand?) popped, and apparently they weren't exceptions from the norm:

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Reply to
larry moe 'n curly

Very true.

Reply to
Ken

Depending on how stressful the position that they are used in - and many such positions these days *are* - I would have to beg to differ. They really are /that/ unreliable ...

Arfa

Reply to
Arfa Daily

components --

Yes, but you're a service technician. I'm talking as an owner.

Reply to
William Sommerwerck

really

If that's the case... then why have I had such good luck?

I just remembered another failure -- bypass caps in the video driver board of my NAD.

Reply to
William Sommerwerck

On Nov 20, 7:13=A0pm, "William Sommerwerck" wrote: > >> It's true that electrolytics are among the least reliable of > components -- > >> but they're not /that/ unreliable. > > Yeah, they are. I've personally changed a couple thousand - 10x more > > than all other components combined - even mechanical wear out parts. >

I also replaced a raft of them in some of my personal gear. The WORST 'lytic caps are the surface mount units which fail early and often. Panasonic FK series are certainly better than OEM parts.

G=B2

Reply to
stratus46

Not exactly. The problem seems to be a mixture of counterfeit electrolyte in some low-ESR electrolytics, manufacturers using electrolytics that are operating far too close to their rated working voltage, and too high a working temperature.

Lifetime on electrolytics is predictable and calculatable:

If you plug the operating temperature, working voltage, etc of your favorite motherboard or power supply into the formula, you'll find fairly short predicted lifetimes. Note that the operating temperature is NOT the ambient or case temp. When you shove a bunch of ripple current through a capacitor, it will get hot from the internal resistance. Measure the temperature with an IR optical thermometer for a better value.

The counterfeit electrolyte problem is probably what you're seeing on motherboards. The crud is still in the system even 10 years after the initial introduction. Some history:

Sure. However, they're very difficult to identify without back tracking the part number or chopping one in half and looking for the black goo inside. The clue is that they tend to be short and not very tall, while conventional electrolytics are much taller:

The caps in the photo really are solid polymer caps.

Dunno and too lazy to tear apart a PS and check.

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Reply to
Jeff Liebermann

Oops, wrong URL. See:

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# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
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Reply to
Jeff Liebermann

How about ceramic caps?

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Reply to
Man-wai Chang to The Door (288

Just that, I suspect - good luck, coupled maybe, with the fact that you buy equipment from the 'better' end of the market which has, at least in the past, tended to be designed to a better spec with a few cents more spent on components. These days, however, even that may not continue your run of good luck. I see equipment on a daily basis coming from what you would normally call 'reputable' manufacturers, that are just badged items of Chinese design / manufacture. Even some of their *better* stuff now borders on a 'con-trick' in terms of design quality and quality of components used.

To some extent, I don't think it is all the capacitors' fault, to be honest. The places that electrolytics are found in today's equipments, tend to be very stressful to them, and when you couple in other factors such as the international law on pain of death that requires designers to place electros as close as is physically possible to anything that runs hot, and then to mount the power supply or whatever board they're on, upside down in the corner of the equipment with the least airflow, it's actually not that surprising that these devices exhibit such *apparent* unreliability. I also suspect that the eco-fanaticism that has given us lead-free solder doesn't help either, as the elevated process temperatures required to get this hateful stuff to stick to anything other than itself, is known to not do some components a lot of good, and I'm sure that, no matter how comparitively brief these additional early-life heat stresses on the electros are, they have to be at least another potentially destructive factor to consider in terms of long life and reliability ...

Arfa

Reply to
Arfa Daily

The caps in the photo really are NOT solid polymer caps.

They're regular Sacon brand conventional wet electrolytics, only housed in the same kind of packaging normally used for polymer caps. Even some of the replies in the message thread where that photo is from mention this. Real polymer caps, except Fujitsu hybrids, don't have explosion rupture cutouts, unlike the caps in the photo -- notice the "K" rupture cutout on top of each cap.

Reply to
larry moe 'n curly

I wonder what's going to happen when these lead-free joints start failing en masse... I can just see a class-action suit against the European Economic Community.

Reply to
William Sommerwerck

I just remembered another "failure"...

Several years ago I bought a KLH Audio (sadly, now out of business) powered woofer, which I tossed in the garage. A week ago I finally got around to pulling it out and connecting to the LFE output of my BD player. (This was intended mostly to keep the main speakers from being overdriven.)

When I turned it on and up its gain (that's "syllepsis"), it made "pumping" noises, all on its own. After a few minutes of "charging up", this went away. It would seem that after a few years of non-use, one or more bypass caps had deformed, allowing instability.

I used to own several KLH Model Eight radios, and though they were 45 years old, none needed a capacitor replacement.

Reply to
William Sommerwerck

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