Apple Lisa repair

[Max1227]

So a while back I managed to get a Lisa 2/5 which wasn't in working order at the time as it suffered corrosion damage to the motherboard and the I/O board. Two days ago I cleaned it and managed to get it working (sort of). It has a few issues:

1) 400K floppy drive always reads and then shows error 10726, even if it is reading a known good disk. This is exactly the same with the ProFile that does work on another Lisa.
2) While the computer warms up it tends to show error 52 which relates to the COP chip. Sometimes this error doesn't show up after it warms up but most of the time it does.
3) The power button and keyboard connector don't work. Even when a keyboard is present and connected the unit won't recognise that one is connected.

What's good:

1) Power supply - been checked
2) Video board - been checked

If I could get the floppy drive to work I could run Lisa test and see what works and what doesn't. Any suggestions what to do would be greatly appreciated.

Thanks
Max1227

 

[NeXT]

I would take some time to make sure the backplane on the card cage is good and clean first. All the devices you mentioned route through it either via the edge connectors on the front or the ports on the back. The COP failing once warm sounds like there's an intermittant connection. Verify you have cleaned the legs on the chip itself and there are no questionable traces around it and patch anything you are suspicious about.

Also, I assume you have lubed and cleaned the floppy drive?

Edited: Oh right. Your keyboard might actually be working but the foam pads inside have perished so keypresses do not register.

 

[Max1227]

Thanks for your response NeXT.

Okay, so previously I thoroughly cleaned the motherboard and nearly all of the surface corrosion has gone. I'm really pleased with how well it cleaned up. However, I agree that it is most likely an intermittent connection and will have another look and clean the chip and socket. Perhaps when it warms up, the contacts expand and then touch which stops error 52 being displayed?

The floppy drive has been cleaned thoroughly by another computer enthusiast before it came to me. He did his 2/10 floppy drive and that works fine, so he does know how to clean these old floppy drives. The chip that gets hot is one of the chips in the top left of the I/O board not the COP.

The keyboard is another matter entirely, while you are right about the foams pads deteriorating the keyboard should be at least recognised by the computer and not show the '?' next to the keyboard icon on power up. Regardless of whether the keyboard is plugged in or not it will still not be recognised by the computer. I can replace the pads but I think I need to replace the power button and keyboard connector module. What do you think?

I also think that the floppy drive and ProFile both being unable to read software is down to a problem on the I/O board. I have a duel parallel port card, does this bypass the I/O board?

Thanks,
Max1227

 

[NeXT]

For testing purposes remove the parallel card.
I strongly you verify you have continuity for all the problematic devices running to the I/O board.

 

[Max1227]

Okay, so I cleaned the I/O and motherboard again and this time I got different error codes on startup. The error 52 still persists but occurs less frequently, the ProFile now shows error 10741 and the floppy disk drive still doesn't boot properly (error 10735 or error 23, boot error). Difficult to say what is wrong with it as the drive does begin booting but stalls after a while.

Edit - Continuity has been tested on the I/O by a specialist and all checks out fine. I also tested it and I can't find any bad traces. Could the Lite card have malfunctioned?