

The Capacitor Plague - jcsalterego
http://www.deadprogrammer.com/the-capacitor-plague

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ejs
Electrolytic caps typically have low lifespans compared to other types of
caps, especially over larger temp ranges.. even with proper construction.

When I use to do design for circuits that needed a long lifetime I would
_really_ question any use of electrolytic caps.

~~~
ladyada
what would you use? tantalums? ive have the joy of recovering old equipment
with dried tant caps on the power rails. (23 of 'em!) maybe tants are made
better these days...

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sketerpot
In _some_ cases you can use ceramic capacitors instead of electrolytic ones.
I've done this exactly because I don't trust electrolytic capacitors to be
anything more than big and cheap.

~~~
ladyada
for a PC switching power converters, such as in this article?

sooo...where are you buying these mystical 2200uF ceramic caps? :)

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zokier
On the positive side, this has led to some improvements, at least in the
motherboard market. I've seen both Asus and Gigabyte market motherboards with
"High Quality" "100% Japanese" capacitors.

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cmos
This almost ruined my company... I still have nightmares about it.

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wyday
Not to dig up the dark past, but could you share more. I'm interested.

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wgj
I once bought a set of monolight strobes (for photography) made by a respected
brand name (Bowens.) Every unit in the set failed shortly after the 1-year
warranty due to failure of the electrolytic capacitors in the power supply. I
used these lights heavily, so for other users, they might last two or three
years. That's still a remarkably short time to failure for this kind of
component.

~~~
pbhjpbhj
A friend has an Apple iMac G4 that they paid a shed-load of cash for and
expected to last well - it nearly made 3 years. The point of failure?
Electrolytic caps in the [overheating] graphics card. The card is soldered in
on the screen side of the mobo.

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jrockway
I think this is a known issue that Apple will fix, however. I remember reading
something related to Apple fixing bad caps in iMacs, anyway...

~~~
pbhjpbhj
They did change the caps from what I've read (there was a court case about it
in the US I gather) but the real fix on teh iMac was putting ventilation holes
in! Who'd have thought. Damned form over function. Also I gather they use slot
mounting GPUs now?

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cakeface
Is this a long running problem? I remember reading somewhere that most of the
problems with old hi/fi and tv electronics were due to bad capacitors which
can easily be replaced.

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pbhjpbhj
I assumed that they were carefully designed so that the electrolyte would go
off just out of warranty (no I'm not kidding) and force a resale.

Perhaps electronic manufacturers that are big enough could have a state
mandated "cost of parts and _actual_ labour costs" repair service.

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aaronblohowiak
actual labor costs quickly make repair more expensive than replacement.

~~~
pbhjpbhj
Yeah, call out charge for washing machine repair is around £100 (minimum),
actual cost is travelling 14 mi (at most where I am)@ 50p (that's the
reclaimable amount for mileage) plus the "engineer's" hourly amount for
perhaps 2 hours (I'm going with £25 per hour gross). So not £157 but £57 - the
company absorbs the downtime costs of callout personnel - this would make a
whole heap of difference in whether it is worth repairing ones washing
machine.

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ghshephard
For about 6-9 months in 2006 We had a series of Dell Optiplex GX 270s that had
a remarkable failure rate - close to 60% of our systems failed. We knew that
Dell must have been having a tough time, when the FIRST question they asked on
a support call was whether we saw any "Bulging Capacitors on the Motherboard"
- I mean, not "Have you Tried Rebooting", or, "Have you tried powering down
for 90 seconds", but "Do you have bulging capacitors."

I'll say this for Dell though - they fixed every last one of those systems
within 4 hours of our call.

I have to wonder whether Large Manufacturing organizations are aware that
there is a good chance that going with subpar capacitor manufactures will cost
them, but do so anyways because of the amount of money they save.

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joe_the_user
How did they fix a hardware failure in 4 hours?

Telekinesis? Teleportation?

Is there something I'm not understanding?

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holygoat
Enterprise customers can get hardware replacements same-day.

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LogicHoleFlaw
When I worked for $BIGCORP we'd get hardware failure calls from IBM to the
tune of " _server_ just phoned in with a drive failure, that part's not in
stock locally, a plane left Atlanta with the part 15 minutes ago."

It was damn slick.

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reedlaw
So, for hardware manufacturers, is there any reliable way to identify good
quality caps?

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noonespecial
Test them under ridiculous load. 120% of peak voltage, _huge_ ripple, let them
get nice and toasty. The bad caps will pop in minutes, a good one can survive
for weeks.

The problem is that the prototypes you get from your Chinese manufacturer will
be made with top quality Japanese components. They'll switch them for the
cheap junk later while you're not looking, about a 10th of the way into your 1
million unit production run.

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Ixiaus
Interesting post, I never knew about the Capacitor Plague! Will be sure to
remember it.

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pasbesoin
Marginal (although not always illicit; sometimes just marginally spec-ed)
capacitors have long been an issue including in consumer electronics.

As an example, the Mac Plus power supply was notorious [well, at least if you
were repairing them] for failing. Some people put out instructions for
upgrading it by replacing a subset of components including IIRC certain
capacitors.

I've also read accounts of people improving the output e.g. of cheaper CD and
DVD players, by replacing certain components particularly in the post DAC
circuitry, again including capacitors, with better quality/rating components.
I've never experienced this first hand, so I can only pass on second hand
anecdote.

~~~
jrockway
This is indeed true. Some (all?) amp designs place resistors and capacitors in
the signal path. This distorts the sound. For one channel, that would be fine,
since the distortion is usually just a phase shift that you won't notice.
(Play a song. Then play a song but start it 1ms after you were planning to
start it. It will sound fine both times :)

The problems start to show up with stereo, though, where you have two channels
to deal with. When you use low-quality components, the phase shift can be
significantly different between the two channels. (Components have a, say 10%
value tolerance. If one channel is +10% and the other is -10%, you have a
problem.)

This difference destroys the phase information between the two stereo
channels, resulting in poor "imaging".

When you replace the 10% tolerance components with 1% tolerance components,
you lose the phase distortion, presumably increasing sound quality.

(I am not an EE, but I have built a lot of headphone amps. The sad part is how
people with $1000 amplifiers often have worse components than an amp built
from $30 worth of parts. Ah, the free market...)

~~~
jrockway
Also, I now have a sudden urge to build another headphone amplifier... :)

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pasbesoin
Glad to be of service. Hmm... and since you seem to know your way around them,
do you take orders?

(Another startup born on HN! ;-)

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jrockway
I did for a while. I am not sure I am knowledgeable enough to do a good job
anymore, however.

If you are ever in Chicago, we can have beer and I will teach you how to build
an amp :)

~~~
pasbesoin
Far north suburbs. I've been a recluse, lately, but maybe when things pick up
for me, I'll see you at one of the HN meetings. (Didn't realize until now that
you're in the neighborhood.)

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mey
So basically, this, plus looking at the pics he links from the over clockers
forums leads me to this conclusion.

You should buy

    
    
         A whole house surge protector
         A really nice UPS supply with a lead acid battery that does line cleaning for your computer equipment.
    
    

Doesn't solve the real problem, but at least saves a significant amount of
hassle... Why systems survive so well in a proper colo environment over most
homes. (Aside from air particles and temperature).

~~~
jws
That is a different sort of ripple. Your big electrolytic capacitors are used
in the AC/DC conversion where the rectified sine wave is smoothed into a
constant voltage.

    
    
      |                           |
      |  _   _   _         ===>>  |
      | / \ / \ / \ /             |--------------
      +V---V---V---V-             +---------------
    

The capacitors store energy during the peaks and return it during the troughs.
The ripple is the current in and out of the capacitor which heats them and
does "stuff-I-don't-understand" to their chemistry.

The article complains that some capacitors don't last their 4000 rated hours.
But even if they do, 4000/24 is 167. All of your electrolytic capacitors are
tiny time bombs.

~~~
billjings
It looks like lifetime is specified in hours of life at a high temperature -
e.g.:

[http://www.rubycon.co.jp/en/catalog/e_pdfs/aluminum/e_BXF.pd...](http://www.rubycon.co.jp/en/catalog/e_pdfs/aluminum/e_BXF.pdf)

Lifetime is specified at 10000hrs at 105deg C.

As temperature decreases, lifetime appx doubles per 10deg C:

<http://www.low-esr.com/endurance.asp>

It looks like a cap rated at 4000h @ 105deg C should last around 60 years at
100deg F or so. Anecdotally I have a guitar amp made in the 60s with the
original electrolytics still working. Sounds great.

~~~
westbywest
As per my other comment on this thread, you can intentionally decrease the
lifetime (aka MTBF) by running the part at 10 or 20% overvoltage, in addition
to extreme temp, to create a corner case and stimulate premature failure in
reasonable amount of time. 20% overvoltage won't kill the cap, as any part has
absolute maximum ratings well beyond what the spec sheet says. Even bad caps
have some degree of guard band, else they would never leave the factory.

