Classic Battery explosion [pics!]

[meander]

Ironically, the other day as i was making a comment about how robust old macs are, and how my Classic has survived so long and still works fine, i take it out to prove my claims, and i get the checkerboard on screen, no boot up sound, the works. so not only do i look bad, but now im worried about my poor classic! (sentimental value, you see) so i open it up to inspect it, figured it was a blown cap like most places seem to indicate and i found this:

So i discharged the CRT and removed the power supply and monitor boards and all that to get a better view, and the battery holder had melted itself off the board and was now laying in the bottom of the case!



The area where the board sits on the inside is pretty gruesome as well:

At this point i have managed to scrub pretty much all of the nasty off, although in the process a crystal fell off and i cant find it anymore, and a lot of the pins on things in the area look kinda of bad, so im fearing it may be a write off:

Fixing the chassis will be easy, neutralize any battery goop that may still be on there, sand down the rust and blast it with some light grey primer and itll be good as new. the exterior of the case is in basically perfect condition, and every other bit inside it works tip top. so we shall see how this progresses, it WILL work again some day, thats for sure.

 

[Solvalou]

Holy hell that's crazy! I thought my IIfx had it bad. 8-o Though that said my mobo was a write-off.

 

[jonathan]

Is that the PRAM battery that fell to the bottom of the Classic's case (and subsequently went thermonuclear)?!!

Its a blessing that no one was hurt.

 

[bigmessowires]

WOW! I never would have thought the PRAM battery could get so hot to do that kind of damage. You're fortunate it didn't actually catch fire and spread to something else...

 

[techknight]

that crystal should be your standard 36khz watch crystal. can be had anywhere.

the machine should still start up without that crystal, it just will not keep time.

 

[meander]

ironically its been sitting on a nice stable concrete floor upright this whole time. The basement is very dry, and is always between 65-72 F. So it never got hot or jostled or tipped or anything!

so lets see, the battery and Y1 are just gone, C1 and C2 look pretty bad, and the legs on D1, D2, UA5, UB5, UA2 and countless vias look pretty bad. unless its prohibitively expensive, im thinking getting a new board might be the best idea

 

[Scott Baret]

I had the same thing happen with a Classic once. It also happened to be standing upright, although my logic board was severely damaged. I'm not sure how long the battery had been leaking when I opened the case (I was actually going in to get the analog board from that Mac to try it in another machine to rule out a CRT problem). The analog board and CRT were both salvaged and put to use in another Mac. The rest of it had to be recycled, as the damage was widespread and I didn't want to keep a badly-corroded chassis around. I'm not sure if I was able to save the case or not (I sold a bunch of Classic cases a while back and don't remember which ones were sent off to new homes).

You're lucky you caught it when you did, as it was confined to one area. The entire side of my board was toast.

 

[Mk.558]

My SE/30 started out as a local craigslist offering for $30 but I talked him down to $10 since "it didn't work".

Plastic case: fine. CRT: No burn-in! amazing. Analogue board: Was working fine when I last used it 2 months ago. Logic board: battery failure and corroded the chassis, ate away the ROM SIMM traces.

Your experience makes mine look petty! As far as my chassis, just stripped the machine to the bone (not hard compared to a modern laptop or Mac mini) and put on two coats of grey primer. Done.

 

[meander]

Your experience makes mine look petty! As far as my chassis, just stripped the machine to the bone (not hard compared to a modern laptop or Mac mini) and put on two coats of grey primer. Done.

Thats what i was planning for the chassis, i suppose i should post a WTB in the market place about a board though, it seems to be pretty bad, at least i salvaged the rom and ram board

 

[Mk.558]

I should say that I did hit up the corrosion with my 4" angle grinder with a wire wheel (wear safety glasses! those things spit wires) and some 400 grit sandpaper.

Looks good as new, minus the color change.

I didn't see any motherboards on eBay, you might have to also post on LEM swap list also. You could also consider an upgrade to an SE/30 or Color Classic -- as clean as the case of the Classic looks, it's just a SE FDHD inside...with no expansion card slot. An SE/30 gives you 16MHz and more than enough memory for cheap, PDS slot, coolness, and the CC grants you color.

Your choice, however. Sentimental value does have merits.

P.S. I was going to say, that third picture in the first post looks like you were thinking about taking up alchemy...Lithium ion (?) battery + steel case + some electronic gizmos = gold? looks like gold on the chassis :approve:

 

[techknight]

Go through all the connections with a multimeter, especially around the bad vias. if the via checks open circuit, just run a wire through it, clean back the solder mask on all the traces leading up to the via, and solder the wire between all the connections, and run it through the via. fill the via with solder, as the wire will help carry it down, this will allow mid-layer connections to repair itself. Ive done this alot on water damaged circuitry. works fine. pick up a roll of 30guage insulated wire at ratshack to complete the repairs.

Sometimes the via may already be filled with solder, just recharge the solder with some fresh solder, and pull it out with desolder wick/braid, (ratshack), and then perform the repair.

I have fixed relatively modern factory radios this way. I had a GMC radio that the VFD tube display had died. turns out one of the via connections behind the big middle power button had open circuit. (fun to find). I work at and help run one of those "fix it everything" shops, and its something I have grown accustomed to.

 

[Dennis Nedry]

I have a Power Mac 6100 that had a similar battery detonation before I got it. I cleaned it all up very carefully and it works fine. You can most likely get that board to work again with some fiddling and testing, maybe a couple of wires here and there to reconnect any traces that are eaten through. I also have two Mac IIs and a IIfx that had similar problems. The IIs were resurrected as well. The IIfx remains damaged in the power area and I still have to jump-start the power supply.

Those things are crazy, I have since removed all batteries from my Macs. I'd rather go without PRAM settings than risk it.

 

[techknight]

or just get a radioshack battery holder for AA/AAA and hang/velcro it on the backside of the machine? run wires to the inside where the old battery was. At least if something happens, itll be on the outside and not in the critical system circuits.

 

[Brooklyn]

I just received an SE/30 for parts, and check out the the battery damage on this thing!

 

[Dennis Nedry]

That's the worst one I've ever seen right there.

 

[Mk.558]

Man those SE/30s are taking some beatings out there!

Comrades, Attack!

I'm hoping you didn't buy that machine looking for a good motherboard. I'm beginning to conclude that if you need a new motherboard, you need another machine. That's what I had to do to get a backup motherboard. (Only lifted one solder pad this time, good thing it only goes to ground so I'll have a wire rigged up to finish it. That's if the small chips behind Bank 2 of the RAM chips and the 470uF capacitor aren't toasted. The board smelled nicely of burning circuit boards before it froze when I last used it. The one in the machine now works fine...just gives me some checkerboard real quick when it boots. I already cleaned the RAM slots with 99% alcohol.)