On Sunday 28 December 2008, Kent A. Reed wrote:
>Gentle persons:
>
>In part because of the need for a parallel port and in part because of
>the latency-inducing problems that seem to arise more often with recent
>chipsets, we EMC'ers often seek out older motherboards/cpus.
>
>I'm curious to know if anyone has run into the problem of bad capacitors
>on their older boards, in particular, with Nichicon capacitors. (see,
>for example, http://en.wikipedia.org/wiki/Capacitor_plague or
>http://news.cnet.com/PCs-plagued-by-bad-capacitors/2100-1041_3-5942647.html)
>
>If bad caps always left the system as dead as a Norwegian Blue parrot,
>then they'd be easy to diagnose. Unfortunately, it is also possible for
>them to result in various headscratchingly odd behaviors in systems that
>seem as if they ought to be working, which is tough to diagnose.
>
>This problem is by no means found only with Dell Optiplex systems of a
>certain age, but Dell sold or leased so many to businesses that they're
>statistically the most likely brand to be bitched about.
>
>I know several on this list have mentioned their success with Dell
>Optiplex GX/SX 260/270/280 boxes coming off lease. These are great
>little machines, especially the SX boxes which I personally like on
>several counts, but I have found I have to be cautious buying them sight
>unseen. Sometimes machines that failed in service were recapped in the
>repair facility, more often the motherboard or the whole machine was
>simply replaced. Good or bad, many of these boards and machines have
>made their way inevitably to eBay and surplus-equipment channels.
>
>Let the buyer beware. Ask if the seller doesn't mention that motherboard
>capacitors are new, replaced, recapped, or somesuch. "Refurbished" may
>be an insufficient description since it could just mean they erased the
>disk drive and wiped the finger munge off the front panel.
>
>Fortunately, there is at least one enterprising person on the internet
>who sells capacitor sets for motherboards but you need a certain level
>of skill to do the job.
>
>Regards,
>Kent
>
>PS - if you've ever tried to bring vintage tube-type electronic gear
>back to life then you already know all about the need to replace
>electrolytic capacitors but you might not have expected digital
>computers newer than your car to have the same problem.
>
Excellent advice Kent. One thing I always look over are the bigger caps
usually located around the cpu socket. Either take a poke at them with a
capacitor wizard (google, great device) or simply shotgun them all if even
one has any signs of a bulged top or leakage around the base. These biggies
are generally still through hole leaded, so normal desoldering extracts them
rather easily. When testing those with the wizard, carefully zero the wizard
with the probes shorted, and anything over .25 ohms tells me those bad
puppies are on their way out.
Test your new caps just as thoroughly, I've bought crap that was 2+ ohms,
brand new. They will make smoke in a few hours if they work at all.
Bad caps are like cracks in a concrete floor. The question isn't if it will
crack, but when.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
I understand why you're confused. You're thinking too much.
-- Carole Wallach.
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