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Classic with battery damage—can it be saved?

macjeffr

Member
I started my Classic last night after waaaay too long, got no bong and a simasimac-like pattern on the screen. I cracked it open and discovered quite a mess. Battery gunk and corrosion all over the place. I've got the chassis soaking in Evaporust, and I soaked the logic board in IPA overnight & scrubbed it with a nylon brush. What would be the best option to remove the rest of the corrosion on the motherboard: vinegar, WD-40, or something else? In addition to a new battery holder and recapping, I know I'll need to at least replace Y1and R85, 86, 88, & 89 on the bottom; but what about D1 and D2, do they need to be replaced? Have I missed anything else? Some of the legs on UA2/UA5 are green; are they/the rest of it salvageable?
Classic_top.jpegClassic_bottom.jpeg
 

ymk

Well-known member
I have a similar wreck. I had to remove the RTC, sound chip and Bourns network to get it semi-working.

Those diodes shouldn't keep it from booting.
 

3lectr1cPPC

Well-known member
The issue here is that it's gone all the way through the board. This means at minimum you have a whole lot of rotted VIAs (those circle things that go through sides of the board), but it's likely that the internal layers of the board are going to be damaged, which you can't really repair. You can always give repairing it a go, but repairing these sorts of boards run a real low success rate. You're best bet may be to get a reproduction board and transfer all of the components over. You can always give fixing the original board a go though.

There's a thread here but a lot is missing because of a recent database crash that took out a few months of posts. Not sure where to look into it for more, but the reproduction boards do exist.

Edit: Found more info here.
 

joshc

Well-known member
I think you'd be lucky to salvage it, the corrosion has gone all the way through the board.

Instead of trying to fix that, I'd look to get one of Kai's Classic reloaded boards so the components can be moved to a new PCB.
 

jajan547

Well-known member
I mean try and drill vias and then worst case scenario use small wire to connect through vias and maybe try sanding that VLSI chip but if it Still doesn’t work that reloaded board sounds fun.
 

360alaska

Well-known member
Classic boards are the only ones I've been able to save after a battery leak. It's best to clean the corrosion, remove parts in the area and check traces.
 

max1zzz

Well-known member
I would think that is savable, the damage is pretty contained and the classic is only a 4 layer board with no signals on the inner layers so is pretty easy to trace out (Schematics are also available for it, though currently only the BOMARC ones are available which can be a little difficult to read. I do have plans to draw up a more modern easy to read schematic for it soon though)

It's a question of how much time you are willing to spend on it, though I would class it as "savable" it's going to be hours and hours of work carefully tracing stuff out and running patch wires. I'll go out on a limb ans say I think all the IC's on that board will be OK but you would want to desolder the RTC and Sound chip and carefully sand and re tin all the legs

As others have said one of Kai's classic reloaded boards would be another good route however this also requires a fair amount of work as you'll need to desolder most of the parts from this board and move them over to the reloaded board (also they aren't avalible yet, though from what I understand it is finished and will be available soon)
 

macjeffr

Member
Update: it looks like the corrosion was holding some of it together. I'm going to hold off doing anything to it until I get a little better at this stuff. Or I find a Classic MB for cheap!

(On a related note, I did my first recap on one of my SE/30s last night, and it was mostly successful! I'm going to make a new post about it, because...well, it was only *mostly* successful.)
 

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Jamieson

Well-known member
I've read recommendations for using vinegar to clean and neutralize gunk prior to wash/soak with IPA. Is this worth doing, or will it just harm things more?
 

jajan547

Well-known member
I've read recommendations for using vinegar to clean and neutralize gunk prior to wash/soak with IPA. Is this worth doing, or will it just harm things more?
Yes it works and is safe just make sure you wash it off, use distilled water tap water will leave weird white gunk around chips after drying or it can.
 
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