D Yuniskis wrote:

On 1/6/2011 9:42 AM, Jeffrey Angus wrote:
? On 1/6/2011 10:36 AM, N_Cook wrote:
?? D ? wrote:
??? E.g., I've been recommending disposing of machines
??? with this problem. The labor to re-cap just doesn't
??? make sense given the book value of machines that
??? exhibit these problems -- especially in light of
??? the fact that you can't be sure that the "repaired"
??? machine is really "100%" (maybe OK for a machine you
??? use informally at home, but would you want to *rely*
??? on it in a commercial environment?).
???
??? I suspect most machines are just recapped and re-used
??? but wanted confirmation or repudiation of that opinion.
??
?? And what percentage of times do you introduce new problems of disrupted
?? multi-layer board traces/vias in the act of desoldering/soldering caps ?
?
? Well obviously, using something a bit more suitable
? than a Weller soldering gun to do the re-cap helps.
?
? But yeah, I did mine, because I bought a pair of
? dells with the cap-itis problems for $50. With $25
? worth of caps they're good as new.
?
? Would I do this for a commercial customer? No, I'd
? give him $25 for the old machine and have him buy a
? new one.

Assuming the old one is *worth* $25... :?

? Then fix his old one for myself. ;-)

That's my point. If it's something you are going to
use yourself it's a different case -- if you later
see it "acting up", you can shrug your shoulders and
give it the old "heave-ho". OTOH, you wouldn't want to
"do your books" on it... :-/

But, the question still stands: did you *examine*
what was actually happening on the board or just
"blindly" replace all the caps and hope for the best?


What happens is that a lot of motherboards were built with crap
electrolytics. They have a LOT of ripple current flowing through them,
which makes them run warm. When the electrolyte starts to dry out the
heating gets worse, till the caps fail. If you use a good grade of low
ESR 105 degree caps like the Panasonic FM series you end up with a
better than original motherboard.


--
What are you looking for, all the way down here?