On 10/22/2012 11:38 PM, Tothwolf wrote:
On Mon, 22 Oct 2012, Josh Dersch wrote:
So, here's a fun one:
See the picture(s) here:
http://yahozna.dyndns.org/scratch/gridcase/
This is in a Gridcase 3+ I picked up last week off eBay for what
seemed at the time to be a pretty great price. Heard some stuff
rattling around inside so I opened it up before doing anything else
and what I seem to have is a few large mineral deposits on the main
circuit board.
It's pretty well localized,and aside from a completely dissolved
drive support post and a few rusted screws there really isn't all
that much rust(amazingly). And thankfully the corrosion that's
present has almost entirely avoided any custom ASICs or other parts
on board. Everything else in the system aside from the bad patches
in the pictures is clean (although the whole thing smells like a dank
basement, geeI wonder why) and the underside is almost corrosion free
so there's a non-zero chance I could get this running again. Except
I have no idea how to go about removing the buildup of... crud... on
this thing. It's pretty solid, I've soaked it for a few minutes in
water and chiseled at it (gently) with the tip of an xacto knife and
I got some of it off that way but it's very slow goingand I'm afraid
of removing what's left of whatever's underneath it before I can
identify it.
Any tips for removing this stuff?
Yuk. Still, I've seen far worse :)
Vinegar and a toothbrush for neutralizing the battery electrolyte and
removing the loose corrosion, then rinse it off really well with water
(hot water and a sink sprayer). I usually remove any remaining
corrosion with baking soda and water formed into a paste, again using
a toothbrush, followed by another rinse. You might have to do this
several times and remove the socketed chips after an initial cleaning.
Thanks. Went over the board with vinegar + toothbrush and it got rid of
the lighter stuff. I let it soak for a little while again and started
picking gently at the larger formations with a knife and I made some
pretty good progress, it's almost what you'd call clean. Interestingly
enough there doesn't seem to be a lot of damage to the PCB, and most of
the chips don't look too bad either. Which is odd -- most
battery-related corrosion I've seen has been very destructive. There's
one DIP switch on the ROM daughterboard that looks pretty much beyond
hope but everything else looks like it may be OK. At the very least the
stuff that got hit by the battery offal is all standard components that
I can replace, assuming I can get them out without damaging anything.
(Aside from ROMs, nothing is socketed here.)
Now the boards are drying, and once that's done I'll see if I can get
any signs of life out of them. The power supply seems to be OK...
This sounds harsh (and is pretty messy), but when you have a board
that looks like that, this is usually what it takes to clean it up. In
the past I've successfully savaged PC boards and test equipment that
had been under 20ft+ of water for more than two weeks due to flooding
(the on-board batteries had of course also burst and the corrosion was
severe).
Thanks for the tips. And I'm glad I didn't have to rescue this from 20
feet of water :).
Josh