just brew it! wrote:
You don't need a circuit or PCB diagram to replace bad caps. Just look up the caps based on their markings and find a similar substitute.
That's true - but before I get neck deep on that, I was wondering if there are damaged traces, or similar problems that may happen. Plus this being a super old machine, a diagram like that would help on maintaining it alive as much as it can.
AFAIK laptops, even ones as old as that, only fail in a few ways you can do anything about:
1) Power brick or battery failing -- replace power brick or battery. For a late-1990s unit, the battery most likely uses 1.2V NiCd or NiMH cells and could be refurbished.
2) Electrolytic capacitor dried out, or swollen and leaking -- replace any units you can find, like-in-kind.
3) Through-hole solder joint broken behind a connector (very common when power ports were still PCB mounted) -- reflow the solder if the joint is cracked, repair PCB using TC buswire if it lifted or broke the trace.
4) Flexible cable broken internally -- salvage the part from another unit.
5) Component or subassembly not working -- salvage the part from another unit.
There aren't many options beyond that, even if you can decode some of the components. On equipment that old, there might be a couple through-hole fusible resistors that failed, but in that case the problem is downstream and thus see (5).