FesterBlatz wrote:

Unfortunately, there also appears to be signs of damage from the original battery leaking. Even though it may not look terrible on the surface, the corrosion will slowly eat away at vias and internal traces. My guess is the exploding cap was a coincidence and the real cause of flakiness is probably due to corrosion damage.

If you want a trouble free 486, any board with soldered on NiCad/NiMh batteries should be considered suspect no matter how clean they look. Not the best news, but I'd suggest chalking this board up as a learning experience and looking for another motherboard that came with a coin cell from the factory.

Thats news to me. I'm familiar with that basic corrosion around the battery holder looks like, but i couldn't really spot that on this board.

What else should i be looking for? Is it how dark and miss-colored the mobo looks?

The green surrounding the mounting hole next to the CR2032.

Take note of all those black spots on the traces and vias directly to the left of the mounting hole. That indicates the corrosive effects of the battery have gotten under the solder mask and is working away at the copper. If you remove the neighboring chip from its socket you’ll probably see more of this underneith it, too.

It’s certainly not the worst case I’ve seen, but in some cases it doesn’t take much before trouble starts to set in.

Oh yikes. I missed your photo from further down on page one. You can see that it has worked its way to (and most likely underneath) the keyboard IC as well as resistors R4 and R5? (Can't quite see the labels) Those resistors have some nasty corrosion on their legs. Jumper block JP2 probably has it as well.

If you are going to use that board, I would recommend you start desoldering and cleaning/replacing components. Hopefully the spread isn't too bad - but you are already looking at replacing a blown tantalum.

Unless you are good at soldering and want to spend a lot of free time to potentially have something that doesn't work - I'd get another board.