Troubleshoot CBM 3040/4040 drives

From: Anders Carlsson (
Date: 2008-08-03 17:21:09


I have picked up a number of broken CBM 3040/4040 drives. They have
various faults, and my hope was to be able to pull parts and assemble
at least one, perhaps two working drives from them. Out of 6 drives, I
have so far managed to find one working DOS board, one drive board and
two mechanisms so I could put together one drive.

In order to verify working parts, I start with plugging in the DOS
board itself and read the error channel from a 8032 using PRINT DS$.
Three of the remaining boards return a lot of garbage in an endless
loop, while two boards do nothing.

I don't think I have any 3040/4040 service manuals handy, although I
found a 2031 one on Zimmers' FTP. Would that be of any use for me?

More importantly, does anyone recognize the fault described above, where
the error channel keeps spewing random data? Which chips if any should I
suspect: 6502, 6522, 6532, ROM... or something completely different?

Maybe those boards who show no sign of life would be easier to get to
work. In that case, which chip(s) are most likely to be broken if it does
not respond at all? I probably should plug in the power LED to see that it
powers up, but if I understand correctly these drives don't blink in any
pattern unlike the 8050, 8250 and the 9000 series hard drives.

In other words, there still are a few things to pick up from my source,
but most of it are partly broken stuff once returned by customers and then
just stored away. All those drives come from that place, and I picked a
few most likely to be repairable.

Best regards

Anders Carlsson

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