They were manufactured with defective electrolyte. It broke down an the ESR went up, causing the capacitors to heat up and swell, or break open at the vents. This caused the CPU power supply to shut down. If the board was cleaned up before the electrolyte damaged the PCB, you could get away with just removing all of the capacitors in the CPU power supply, a careful cleaning, then installing the new capacitors. This is where an ESR meter comes in handy. The lower the ESR, the better the electrolytic. You can compare an old one with a new one and decide if it needs replaced, and you don't even have to remove the old one from the circuit, first.
--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
Just out of idle curiosity; why is it that this sort of stuff only seems to appear in the audio world which exists up to a few tens of kilohertz.
Folks working in the high Megahertz or Gigahertz ranges with highly sophisticated filter requirements don't seem to get into these religious arguments; at least in public.
Hey, thanks a bunch. This is what I was looking for.
I have seen things like the $400 gold-plated oxygen-free copper wall outlet and $79 shielded optical audio cable, and I know that people will pay a great deal of money for hype in this business, but I still think that applying a few bucks in the right place can make a big difference. I'm not going to worry about spending 5 times too much for three or four capacitors when I have to spend three hours taking something apart and replacing them. Nor am I under the impression that adding an exotic handmade cap to my cheap old heathkit tube amp will transform it into a prized audiophile component. But I'm not buying a million of the things; I can afford to splurge. At least then I'll know whether it made any difference, and then I can make a non-smartassed reply the next time someone asks about it. :)
Yeah. I'd like to clarify that my "It's not baloney" statement applied only to the computer motherboard cap replacement thing. I think that most (maybe all) of the audiophool stuff is baloney.
The problem with capacitors is that they're parametric. That is, their capacitance changes dynamically under the influence of some variable, voltage and temperature being the usual suspects. Audio freaks don't usually realize it, but the reason some caps sound different from others is that they exibit a greater capacitance change with signal going through them than others, and thus "color" the music differently. Rest assured that if you substituted a high-K ceramic for a polyester cap with the same capacitance and voltage rating, things would _definitely_ sound different!
Now, you might say that's because the ceramic is microphonic, and you'd be right, but it's microphonic because it's parametric!
What happens to make capacitors parametric is that the electric field physically deforms the plates, causing the spacing between them to change, which causes the capacitance to change.
---
--- Six days, actually. "On the seventh day He rested."
This is mostly because when you get above audio, you are in a world where everything is narrow-band. Compared to 8 or 9 octaves of audible frequencies, 802.11 isn't even a semitone interval. Even "wide FM" gives a channel just a tiny sliver of an already skinny band. Cellular systems employ frequency-hopping, but even then, nonlinearity is less of a problem because the information being transmitted is digital. And of course, in computers, things are as narrow as they get; the clock frequency never changes unless you put another processor in.
The only people who are worried about nonlinearity in the RF range are probably the ones designing top-secret satellite imaging systems and weapons, and they obviously don't care how much a capacitor costs.
And do please explain how this equates to anything other than L, C and R !
There are rectifying effects with electrolytics that can be provoked by poor application but I challenge you to show that one film capacitor 'sounds' different to another.
Well, the currents in those power supplies are also quite, uhm, substatial, for teh little caps - that are close to warm stuff liek CPU and switcher as well.
One Pentium D: 1.3 volt, 130 watt thermal design power (pek is higher, average is lower) - that's 100 amps for the little caps.
Sure. The impedance of an ideal cap is given by Z=1/sC. This means that if you plot Z vs s, you'll see a nice power curve that you can build into an op-amp to make a low- or hi-pass filter with exactly the dB/octave you're looking for.
The impedance of a real capacitor, however, can only be approximated by the formula above. This is because of several factors, including the fact that the plates are often coiled (giving them inductance), very thin (giving them series resistance), and separated by a very thin and not 100% pure electrolyte (giving them shunt resistance). Obviously, not everybody makes them the same way, and that's why they don't all work the same way.
Now.. throw in the fact that some electrolytes respond chemically to electric fields, and that some metals behave in a non-ohmic fashion when you beat them very thin and layer them in exotic chemicals. This causes some caps to store energy in ways other than the simple electric field, from which our trusty impedance equation was derived. This means that interesting things happen to the impedance depending on frequency in a way not even related to capacitance.
Do you want to see it? google around for capacitor linearity. I found this pretty interesting page in a few seconds:
formatting link
You should be able to see now why Panasonic makes about three hundred different kinds of caps for all different applications, instead of just saying "a cap is a cap is a cap" and offering only one line. Some are better for audio, some for RF, some for power filtering, and so on to an even higher degree of "ad nauseam" than that found in this thread.
So now we're just left with the highly subjective task of judging the "quality" of one form of distortion over another. While it's true that the nice perfectly linear response of an ideal cap will give us perfect performance, the fact that guitar amps still use tubes pretty effectively demonstrates that better is not always better. Our ears are even less linear than eighty-year-old ham radio capacitors, and on top of that, our brains have this idea that some noises sound neater than others. There's no way to numerically rate one brand over another when it comes to aesthetic quality, but I'm willing to consider a sincere opinion that "so-and-so makes great-sounding caps."
Obviously this argument can go nowhere unless you are willing to accept the possibility that the truth lies somewhere short of the audiophile dogma, but well beyond your assumption that every electrical component works just the way they told you in high school physics.
--
What difference would it make?
If I said yes, you\'d counter with that the effects I heard were
subjective, and if I said no you\'d counter with that I had no
evidence to support my claim.
So, let\'s take a step back and see whether we can find some common
ground here to determine whether the effects are real or not, OK?
Maybe even build a circuit or two...
For starters, are you willing to concede that the capacitance of
capacitors is, indeed, parametric?
You don't even understand the construction of a capacitor. (BTW, what is "100% pure" electrolyte? Surely they use rather impure electrolytes, capable of anodizing the aluminum used, and full of charge carriers?)
"plates are coiled" The plates are coiled _in parallel_. This makes a planar transmission line, that happens to be looped together. The seperation between the plates is almost negligible (thousandths of an inch for high voltage capacitors). In addition, the transmission line is balanced, having the same but inverse field on both sides of the plate, so as to maximize charge density of the capacitor. Not only is this a transmission line, but because of the low seperation (inductance) and high capacitance, it has a very low characteristic impedance as well.
Nonetheless, the inductance can be seen seperately (not in isolation) at low frequencies. I suppose the effect is the manifestation of the delay of moving the charge through the transmission line?
"very thin" That depends. Obviously: consult your datasheet for ESR!
"shunt resistance" WTF? Do you mean leakage? Leakage is determined by the dielectric, duh...
Some, *maybe*. Thin? Hell no. There's at least a million atoms left in the thickness of that sheet, and that's a pretty thin sheet! There's no difference between 10^6 and 10^9 atoms thickness in a piece of metal, no matter how you crystallize it.
Yep, absolutely. But you'll note, very carefully, that nowhere is it ever mentioned, with sound scientific tests backing it up, that capacitors sound different!
Ah, yes. Well then, there's a simple solution to that: double blind testing with large (representative) samples of a population. Statisticians do it all the time, with wonderful results.
Did you know there are forums were merely mentioning DBT will get you banned? LMAO!!
Tim
-- Deep Fryer: a very philosophical monk. Website:
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.