Tales from the DARK side
Mar 16, 2006 at 5:52 PM Post #2 of 15

JahJahBinks

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In the analog design course I took in our company, it stated that the use of aluminum oxide electrolytic capacitors is discouraged because they have significant leakage, value is highly temperature dependent, and they have a limited shelf and operational life. A better choice is tantalum electrolytic capacitors. (it also depends on the application)

The article said about capacitors made in Taiwan, so at least it's not a wide spread problem.
 
Mar 16, 2006 at 6:27 PM Post #4 of 15

rickcr42

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This kinda stuff is almost too funny until you think about all the "clone caps",knockoffs,mystery caps populating amps coming out of China.I wonder how many of the current "ooh that looks nice,bet it sounds good" inexpensive amps will be blowing up in a year or two.

I realise cheap labor makes for cheap parts and a low cost amp but when it comes to certain parts even the raw materials can get pricey so when I see an amp populated with Black Gates or Elnas,do the math and the caps alone cost more than the entire amp even in groups of 1K I wonder if some enterprising person is not just slipping a "BG" cover on a crap capacitor with a limited lifespan and questionable sonics.

then again I am suspicious of EVERYTHING on the "if it seems to good to be true it proably is" theory
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Quote:



Have known about those cats for a while but never had the urge to post anything.They seem to have things under control without my help
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Mar 16, 2006 at 6:40 PM Post #5 of 15

Paragon

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I have a board with top leak caps by the AGP slot.. explained why I would get in game lock-ups all the time. Didn't notice until I was upgrading. Board is still in use on another computer with underclocked AGP settings. Will be replacing caps soon as I get some new ones.

Board is Abit KT7A-Raid v1.2 that came out back in.. whenever it was.

Also have seen an MSI board with bulging caps - replaced under warranty.
 
Mar 17, 2006 at 12:28 AM Post #6 of 15

Garbz

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When dad's motherboard died for unrelated reasons I went around looking for replacements. A mate gave me a spare board which he said was unstable but worked. All memory tests even underclocked ones failed. Closer inspection showed all the caps aroudn the memory slots were leaking from the bottom. I simply substituted from one board to the other. Even though the cap values didn't match the system is now perfectly stable and is being used as our server. (73 days uptime thus far
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I believe this problem was causing major issues for ASUS and ABIT who've had to replace seveal defective boards (Product recall????)
 
Mar 17, 2006 at 12:40 AM Post #7 of 15

Thaddy

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A few months ago I fell victim to those crappy capacitors. I heard a *pop* one night while laying in bed, and rolled over to find out my computer was off. A dead motherboard and CPU later, I found out that about 13 capacitors had kicked the can, and didn't go down without a fight.

edit: The board was the Epox 8RDA+, a model which was confirmed to use a ton of these bad apples.
 
Mar 17, 2006 at 1:29 AM Post #8 of 15

DaKi][er

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Quote:

Originally Posted by Thaddy
edit: The board was the Epox 8RDA+, a model which was confirmed to use a ton of these bad apples.


The caps on my 8rda were going that way too, lucky I replaced them with some Rubycon ZL before they got that bad, and it even overlcocked better than it ever did after doing it too
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Mar 17, 2006 at 10:59 AM Post #9 of 15

mono

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Those who know me, unfortunately know I repair motherboards from time to time. I've replaced untold hundreds of bad caps. Some of them are actually "ok", not defective per se but the board design, system cooling or other variables (like overclocking or someone doing an upgrade unsuitable from a current perspective like running a 1.4GHz Tualatin Celeron on a generic '98 BX board) caused failure.

It was once thought the truely defective caps would fail merely by holding a charge, no ripple at all, but it's worse than that. I have a board I keep around as a reminder, it hasn't been hooked up for well over 18 months (is just sitting loose) and the cap swelling is still progressing. Funny thing is, that motherboard was one that had it's original caps fail, I'd replaced those caps a few years ago with some that weren't known defective at the time, and now many of the replacement caps are also swelling up and leaking.

If only it were generic caps, but some of the same brands that had problems are still used on new major-name boards today, albeit different cap family/models than previously, but then again for all we know they could've just changed the model name, put a different colored sleeve on them and that was the extent of the fix.

Lelon, (G-)Luxon, Tayeh, Jackcon, JPCON, Chhsi, GSC, Ost, et al. Fortunately most manufacturers aren't using these in high current areas anymore where the higher ESR->heat has the worst effect, but PCChips (and their relabels) still extensively use Ost where most manufacturers cutting fewer corners, wouldn't.

one thing the linked article has completely wrong, "If you are qualified to fix it yourself, Radio Shack sells the caps". Absolutely not, Radio Shack has nothing in the same ESR-zip-code as what is needed. The Panasonic FMs many of us use here will work though, among others.
 
Mar 17, 2006 at 11:58 AM Post #10 of 15

Sovkiller

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Quote:

Originally Posted by DaKi][er
The caps on my 8rda were going that way too, lucky I replaced them with some Rubycon ZL before they got that bad, and it even overlcocked better than it ever did after doing it too
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Another here, mine gone to the dark side also, same couse, bad caps....
 
Mar 17, 2006 at 8:23 PM Post #11 of 15

rickcr42

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Quote:

one thing the linked article has completely wrong, "If you are qualified to fix it yourself, Radio Shack sells the caps". Absolutely not, Radio Shack has nothing in the same ESR-zip-code as what is needed.


Low ESR Nichicons,Radio Shack
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Mar 17, 2006 at 9:38 PM Post #12 of 15

mono

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Quote:

Originally Posted by rickcr42
Low ESR Nichicons,Radio Shack
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?? I've never seen but a few gen-purpose Nichicons at the 'shack, which families? From time to time I've seen a scattering of the PL/PM series but never individually, you always had to buy a few packs of the assorted caps to get those. Then you have 3 dozen junky little caps to throw away and the two reasonably sized PL's in the pack ended up costing over $2 each. I suppose if money was no object that would be ok except it seemed about 1 in 4 or 5 packs had acceptible sizes, so unless the store had half a dozen pegs full of assorted cap packs, there was no way to get enough to do one board.

Here's a bunch of Nichicon pictures, of those represented, I'd use the P(x) series on an older (generation) board but only the H(x) series for a semi-modern board. I have never seen a single H-series at Radio Shack.
 
Mar 17, 2006 at 9:50 PM Post #13 of 15

rickcr42

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Quote:

?? I've never seen but a few gen-purpose Nichicons at the 'shack, which families?


off hand can't remember numbers off hand (and the way the shack is going maybe no longer available ?) but the big purple can Nichicons are low ESR caps.The "gray" rat shack nichicons are general purpose generics
 
Mar 17, 2006 at 10:01 PM Post #14 of 15

mono

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Quote:

Originally Posted by rickcr42
off hand can't remember numbers off hand (and the way the shack is going maybe no longer available ?) but the big purple can Nichicons are low ESR caps.The "gray" rat shack nichicons are general purpose generics


We might be talking about a whole different category of "low ESR"... either that or all the 'Shacks around here are pathetic. Take a typical low esr cap and put it in a 75A switching supply circuit and it may not fare a lot better than the original did. Depends a lot on the specifics though, some parts gobble power and others nibble. Nichicon's H series are about the only thing they make in a (low cost, 'lytic), suitable for modern boards. Part of the problem is the limited real-estate, if there were room to swap in 12.5mm diameter caps all the time that'd make things a lot easier but more often there isn't, 8-10mm is about it and sometimes height limitations too.
 
Mar 17, 2006 at 10:39 PM Post #15 of 15

rickcr42

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Quote:

We might be talking about a whole different category of "low ESR"... either that or all the 'Shacks around here are pathetic.


could be a combination of the two
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One thing I know is the shack (or at least did before i swore i would never enter one again) because my wife manahed a store at one time.this allowed me to get into the cookie jar and find what was and was not usable.

Manty timnes I would find a gem in the rough and when I attempted to purchase in any quantity would find they changed "jobbers" to have a larger profit margin and would have to get my wife to go on the inter district network and pull up the parts number acording to shipping dates at which time I would drive all over the damn county to get the "one here two there" of what I needed
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It very well could be the article mentioned above and my personal experiences were valid at the time but are no more or maybe it is a stor-to-store or districting thing.to that i just don't know
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