pl212
Active member
I have a Lisa 2 that worked for many years, but has recently started giving an Error 52 -- and also immediately starting up when powered, instead of waiting for the power button. (Interestingly that light remains unlit despite the machine turning on.)
Here's what I've tried so far:
1) Replace COP chip with (allegedly) known-good chip.
2) Replace I/O Board with a different (allegedly) known-good board.
3) Swap another COP chip to both the original and replacement board, for a total of three COP chips tried.
4) Swap in an (allegedly) known-good CPU board
5) Test continuity between the internal keyboard connector and the 1/4" keyboard plug.
6) Made sure all contacts are clean and undamaged
All of these result in the exact same error, 52, and the same instant-on behavior.
Spelunking around for Error 52 shows these interesting discussions:
Here's what I've tried so far:
1) Replace COP chip with (allegedly) known-good chip.
2) Replace I/O Board with a different (allegedly) known-good board.
3) Swap another COP chip to both the original and replacement board, for a total of three COP chips tried.
4) Swap in an (allegedly) known-good CPU board
5) Test continuity between the internal keyboard connector and the 1/4" keyboard plug.
6) Made sure all contacts are clean and undamaged
All of these result in the exact same error, 52, and the same instant-on behavior.
Spelunking around for Error 52 shows these interesting discussions:
- https://lisalist2.com/lisalist1/0569.html (Swapping CPU boards fixed it.)
- Other ideas from that thread: bad 6522 for the keyboard?
- https://yesterbits.com/2012/04/25/error-52-and-mystery-of-the-missing-cops-chip/ (Swapping COP chip fixed it.)
- https://68kmla.org/bb/index.php?thr...-help-troubleshooting.7248/page-2#post-412231 (Fixed by repairing a bad trace)
- (Another user in the same thread also fixed by repairing a bad trace)
- https://68kmla.org/bb/index.php?threads/apple-lisa-findings.35503/ <- User found an out-of-spec power supply was causing the COP chip to malfunction.
- Problem in the actual motherboard backplane that is blocking communication.
- Problem in the female jack where the keyboard plugs in, or in that larger module.
- Failing 1.8 power supply is no longer supplying correct voltage (see last link below)