Power supplies with solid polymer caps

[Daniel Prince]

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.

 

[Pen]

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.

I've found pc coo;ing to be the most reliable supplier. Not always the
cheapest, but highly reliable.
http://www.pcpower.com/index.html

 

[larry moe 'n curly]

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?

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

www.JonnyGuru.com
www.HardwareSecrets.com
www.HardOCP.com
www.XbitLabs.com

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).

 

[William Sommerwerck]

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.

 

[JW]

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.

I think the OP is referring to claims such as these:
http://event.asus.com/mb/5000hrs_VRM/

*cough*

 

[William Sommerwerck]

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

I think the OP is referring to claims such as these:
http://event.asus.com/mb/5000hrs_VRM
*cough*

*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.

 

[stratus46]

*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.

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

G²

 

[larry moe 'n curly]

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.

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:

www.dfrsolutions.com/pdfs/2004_Electrolyte_Hillman-Helmold.pdf

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:

http://farm3.static.flickr.com/2350/2461471181_352c511a5a_o.jpg

 

[Ken]

I have read that electrolytic capacitors are the least reliable
component in power supplies.

Very true.

 

[Arfa Daily]

*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.

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

 

[William Sommerwerck]

It's true that electrolytics are among the least reliable of
components --

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

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

 

[William Sommerwerck]

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 ...

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.

 

[stratus46]

parts.

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

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.

G²

 

[Man-wai Chang to The Door (28800bps)]

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.

How about ceramic caps?

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http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa

 

[Arfa Daily]

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.

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

 

[larry moe 'n curly]

The caps in the photo really are solid polymer caps.

<http://www.dslreports.com/forum/r19863881-Solid-Polymer-Capacitor-Failure>

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.

 

[William Sommerwerck]

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 ...

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.

 

[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.

 

[david]

How about ceramic caps?

You cannot get large capacitance values in a small package size with a
ceramic dielectric.

 

[larry moe 'n curly]

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, 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.

So why do the good brands tolerate those conditions so well while the
same old junk brands don't? And contrary to what you say, most of the
caps aren't in hot spots but are running at under 60 Celcius

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,

But the problems with junk capacitors showed up way before the switch
to lead-free solder, and only one of my RoHS mobos has so far popped a
cap, probably more because it's newer (late 2007), not because it's
better, but it has the same OST brand junk caps.

The real fault lies with the makers of junk, period.