Troubleshooting the disk drives in a 8296D

From: Marko Mäkelä (
Date: 2004-11-21 19:33:02

Remember the CBM 220 (a.k.a. 8296D) whose drive analog board was broken in
two halves?  Well, I ended up buying it, and thanks to Ruud Baltissen, the
system now has a healthy-looking analog board.  However, the drives still
do not work.

When I power up the system, the disk status LED between the drive slots lights
red for a while (approximately 1 second), then green for approx. 1 sec, and
then it flashes red once very quickly.  The LEDs next to the drive slots
do not light up.

When I power up my 8250, the middle LED does approximately the same thing,
but when it blinks red quickly, also the two LEDs at the drive slots blink

The drive complains either READ ERROR or DRIVE NOT READY when I try
DIRECTORY.  The drive LED (next to one of the disk slots) remains lit,
even after querying the error channel, until I issue the "UJ" command.

When I try to format a disk, the drive complains WRITE PROTECT ON, no
matter which way the disk is inserted, and no matter if I swap the drive
cables.  (For each drive, there's one connector for the R/W heads, and
another for everything else.  I suspected that it would be accessing the
R/W heads in the wrong drive.)

I cleaned the R/W heads, but there was no visible dirt.  On the other hand,
many keys on the keyboard didn't work before I took the keyboard apart and
washed everything except the circuit board.

Does anyone have any ideas where to begin troubleshooting?  Is the behaviour
of the LEDs normal?  I'd otherwise swap parts with my 8250, but the built-in
drive unit of the 8296D looks completely different.


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