On 7/22/2014 10:44 AM, CRPence wrote:
On 21-Jul-2014 22:17 -0500, Steve Landess wrote:
http://www.theguardian.com/technology/blog/2010/jun/29/dell-problems-capacitors

I had previously composed but never sent a reply to this thread, with
some comments about my apparent power [supply] issue seeming similar.
Now I am left wondering if some IBM ThinkPad were affected by that
issue? While I find mentions in the badcaps forum, I did not encounter
any model lists anywhere. I recall looking for any dust, crimps,
swelling, or any other /physical/ issues, but not noticing any. I might
have to go back for a new look. Would be nice to have that system back.

The electrolytic capacitor issue was very widespread. I don't know of a
canonical list of affected equipment. Visual inspection will reveal
extremely bad capacitors; swelling, split vents, ejected rubber seals,
but the capacitors are out of electrical spec long before physical
damage is visible on the outside.

The problem is that the electrolyte is getting overheated and drying
out, changing the electrical characteristics of the capacitor. The caps
that typically fail are filter caps, regulating the ripple in power
supply outputs. As the capacitance goes down, the amount of ripple
rises. The downstream components can handle a certain amount of ripple,
but eventually the ripple gets large enough to be on the hairy edge for
them. That's when the intermittent failures start happening.

The only real way to know if the caps are bad is to pull them and test
their Equivalent Series Resistance and Capacitance figures. Of course,
the cost of new caps is so low that simply replacing them is economical
enough, especially considering that the real 'cost' is the time to
remove the existing caps.

My favourite programming language is solder, so this is old hat for me.
Not everyone is as comfortable with a soldering iron and PC board. If
one is very new at this, I'd suggest going to a thrift store and picking
up an old TV, radio, etc and practice de-soldering on that board.

--buck


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