15 Jan
2024
15 Jan
'24
7:51 a.m.
On Sun, 14 Jan 2024, Tim Mann wrote:
and hasn't been used much, but last time I tried
it, it would no longer
read any data from the back of a floppy, only from the front. I use it with
a Catweasel and my cw2dmk software, so I was able to try a few experiments
from the software side. What I see is just plain noise coming out on the
data line when reading the back.
I suppose that you are using two-sided floppies ;-)
The drives that I know only have one path from the head to the computer,
i.e. they only have one read amplifier and so on. The selection of one of
the two heads is done with biasing the corresponding diodes (used as DC
switched AC gates, labelled CR1..CR8 in the schematics).
I would check the path from the side select signal up to there. Maybe the
head select driver (IC 5A) has a problem. Check pins 6 and 7, as well as
pin 9 (side zero select).
Christian