Repairing A4000 leaky NiCd damage?

Peter Coghlan cctalk at
Fri Jan 2 15:34:28 CST 2015

> Went through this entire process on my A4000 a couple of years back. In my 
> case there was damage to traces underneath several of the adjacent chips 
> and the clock chip was dead to boot.  I would suggest soaking the board 
> overnight in dilute vinegar in addition to washing, since the alkaline 
> crud gets into via holes where washing won't dislodge it.  If traces are 
> not already eaten, this may eliminate the need to remove the DIMM sockets.

I've often seen it suggested that acid or alkali contamination should be
neutralised somehow.  In theory it seems like the thing to do but I've always
had doubts about how successfully this can be done and whether the cure might
do further damage on top of the original contamination.

In practice, I can't see how it would be possible to get the concentration of
neutralising agent even approximately right and how it would be possible to
cover all the contaminated areas and yet avoid getting it on non-contaminated
areas and maybe causing new damage there.

And then there's the wondering whether the resulting wet salts will do different
or worse damage than the original contamination before they are washed off
and whether they might be dangerous to people?

Unusally for this list, everyone seems to agree that it is the way to go
but it still seems a bit black art to me.  Yet we have long and inconclusive
debates about retrobrite and the like where there are opionions on both sides
of the fence.  I'm not saying I'd like to have a big debate about this, just
wondering if I'm missing something somewhere.

Peter Coghlan.

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