[mythtv-users] Is my video card toast?

f-myth-users at media.mit.edu f-myth-users at media.mit.edu
Tue Apr 21 18:38:14 UTC 2009


    > Date: Tue, 21 Apr 2009 11:18:47 -0700
    > From: Gabe Rubin <gaberubin at gmail.com>

    > Would this have been caused by overheating, age, or something else (or
    > impossible to tell as it is a case-by-case situation)?  I just don't
    > want to have to repeat this process with a my replacement card.

All electrolytics age; their lifetime is one of the elements of their
specifications.  Among other things, electrolyte can leak out (which
you saw).  Elevated temperatues dramatically raise the rate at which
they age; many reactions run 2x faster for every 10-20 degrees C of
increased temperature, and it doesn't take too many doublings for
your 20,000-hr cap rating to be into the hundreds of hours instead.

[By the way, if you've been handling the gunky bits, wash your hands.
Electrolyte can be fairly corrosive.  And wash it off the board, too,
if you intend to go futher with it.]

Cheaper electrolytics typically age faster (or are underspecified for
the sort of ripple currents they're subjected to, leading to high
temperatures in the cap and thus starting a thermal runaway that
eventually ends in premature failure).  There was a famous instance a
few years ago where a knock-off supplier of caps (using technology I
believe was, uh, "imported" by a former employee of a different
company, but who didn't get it quite right) produces a gazillion
electrolytics that all failed really early.  A lot of motherboards
used those caps and failed early themselves.

If you were handy w/a soldering iron, you might be able to read
the caps, find new ones with similar ratings, and solder new ones
in.  Your board might work again.  If the alternative is to throw
it in the trash, and you've got some time to kill, that might be
an interesting experiment.  There's often nothing more satisfying
than reviving a toasted piece of equipment from the dead.

And get a better case fan. :)


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