Classic II beyond repair?

[Tsiatric]

I got a Classic II with assorted goodies off Craigslist for a good deal, with the only problem being the infamous leaking logic board caps. Not having a decent iron at the time, I decided to clean the board as best I could with q-tips, alcohol, and patience, just to see if the system would work at all. And it did! For a time. But when it came time to properly replace the caps, that's when it all went wrong. Pads and traces starting lifting left and right, with some traces snapping off the pads entirely. I tried different temperatures and techniques, but nothing made it better. In the end, about half of the pads came off. Is there anything I can do to salvage this? Everything else about the machine works great, even the hard drive, so it'd be a shame for this to become a shelf ornament.

 

[Tim S]

I read of some replacing the smd caps with tantalums but please do your own research to confirm this.  Maybe with using radial tantalums it might be easier to find new points to solder them to that have continuity with the old spots that lifted.

 

[Tsiatric]

Based on my readings, tantalums might work. But the trouble is finding where the old caps connect to the board in the first place; especially C15. It looks like it connects to one of the pins on the 344S1033-01 chip, which seems to be a digital audio filter. Trouble is, I can't find a data sheet for it, and the trace goes under the chip. Since I can't get a continuity test off the trace that's left by the ruined pad, I don't know which pin it goes to.

 

[marcelv]

I always use tantalums to recap.

C15 is connected between 2 pins op 344S1033-01, if you don't connect it the sound does not work, but the mac will 

 

[Tsiatric]

I can live without sound for now, if it means it'll boot. By chance, do you know which two pins the capacitor connects to? And for that matter, are any of the other capacitors not needed for the machine to boot?

 

[marcelv]

I don't think you "need" any of the caps to boot.

The most important thing is to clean the board to remove alle the leaked cap fluid.

c15 connects to the pins as shown in the picture

 

[Tsiatric]

Huh, well I'll be. I was under the impression they were necessary components for the computer to function. I figure I might as well replace the caps in the spots with both pads intact though. Guess then my only question is how will missing those caps affect the longetivity of it? Will parts be more prone to failure or undesired behavior?

 

[marcelv]

The challenge you have is not the caps but the repair of the traces, the board will not work until you repair these.

there are a number of traces which have the capacitor island in the middle so the connection is broken.

Also for example the trace which runs between the islands of C5 and goes to U8 has to be repaired.

Add the caps when yo have checked (and repaired) the traces around and under the caps.

 

[Tsiatric]

I didn't have the proper tantalum caps on hand, but I did have the right aluminum ones, which should be fine for now. After cleaning the board within an inch of it's life, I replaced them everywhere there were two pads (i.e. C4,5,8,10,11,12,13) and it booted up just fine- screen was fine, disks loaded, just no sounds since I didn't attach C15 to the chip. I'll probably get the proper tantalum ones and do a better solder job soon, but for now I know it works!