This Macintosh Classic was given to me by my friends, Paul & Margaret, so it means just a little bit more to me than the average Classic.
These machines are somewhat notorious for leaking capacitors and batteries. The only other time that i worked on one of these machines, the corrosion was awful.
I started by opening up the machine for a look. I was happy to see that the battery had not leaked and that, although the logic board capacitors had leaked a little, the damage did not seem to be severe. The analog board seemed to be in good shape.
I gave the logic board a quick clean and then powered it on. I was greeted with a chequerboard.
At that point, i ordered some replacement caps. When they arrived, i carefully removed the old ones with hot air. With the old caps off, i could clean more thoroughly and then inspect the tracks around the capacitors.
Cleaning involved a good wash with PCB cleaner, removal of corrosion with vinegar and then several days with deoxit in stubborn spots.
I carefully scrapped away loose solder resist and cleaned up the copper beneath. A fault was clearly visible under C8. I made the connection using kynar at the source and destination pins (an address line to the ROM). I didn’t want to have a dodgy track repair under a component.
I tinned all the exposed traces and then replaced the capacitors with tantalums. The battery was replaced.
With the track repaired, the machine came to life!
This machine has a total of 4MB of memory. The original hard disk is going for the moment. The floppy disk is operating nicely so it may be a handy bridge machine for 800k disks.