From: Marko Mäkelä (marko.makela_at_hut.fi)
Date: 2006-12-12 10:04:52
On Tue, Dec 12, 2006 at 04:15:54AM -0300, Andrew Wiskow wrote:
> I've got an issue with an old off-white VIC-1541 disk
> drive... It doesn't play well with others, for some
> reason... I've plugged it into a C64 and a C64c by
> itself, and it works just fine... But plug other
> drives into the serial chain, and none of the drives
> work. All drives are assigned different drive
> numbers. I've also tried swapping out the serial
> cables, but it sttill doesn't work. Has anyone heard
> of this happening before? Any ideas how it can be
> fixed???
You could try replacing the chips connected to the serial interface.
They could be slightly damaged in such a way that they are putting
more load on the serial lines.
For more information, see the service manual
http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/service/
and the (slightly unreadable) schematic diagram for the long board:
http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/tech/1541-35.gif
I'd replace the UC1 (74LS14) and UD1 (7406). The newer (short) board
has similar inverters near the serial bus. I don't know of the 1541-II;
it might have these integrated in a big ASIC.
Marko
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