help! shugart 801 - test-drb@ccmp.vtda.org

22 Jul 2003

...
 From: Joe &lt;rigdonj(a)cfl.rr.com&gt;

At 09:26 AM 7/22/03 -0700, you wrote:
  From: Joe
&lt;rigdonj(a)cfl.rr.com&gt;

    I have several systems that use Shugart 800-1 SS 8" disk drives. I've
got several defective drives plus I've been wanting some spares. Last week
I picked up 10 Shugart model 801 SS drives. Today I tried to use them on
the same systems but I can't make them work. I've set all the jumpers and
straps exactly the same as in the 800-1 drives but the 801s aren't working.
The system knows the drive is there and detects the disk being in place and
rotating and that the drive door closed but the drive never gets the head
load signal. I'm using the same system, cables, power supply, etc with both
drives so the only difference is the drives themselves. I've tried a couple
of 801s and gotten exactly the same results with all of them so I don't
think that it due to a drive failure. Anybody have any experience with
these or have a good idea of what's wrong?

   Joe

Hi Joe
 You do know that some of the drives have data separators.
I forget which numbers have this and which don't. I don't recall
if the 800-1's had them or not. If you are using these for
M2FM, is seems that I remember that the bandwidth was slightly
increase on these drives. As I recall, there was a capacitor
change in the pre-amps.
 Those are the only things I can think of.
Dwight

   You may be right but the head isn't even loading so I'm not even getting
that far. I have a Shugart 800/801 manual but it's vague about the
differences between the two. But IIRC the 801 is designed to handle hard
sectored disk and the 800 doesn't. I'm wondering if the index pulse
detection circuit is different and may be causing a not ready condition or
something similar. (Yes I know I can check it with a logic probe but I
didn't have one where the machines are located so I havne't done that yet.)

     Joe

Hi Joe
 I missed that about the head not loading. Is the drive getting
a head load signal or is the controller waiting for some status
line from the drive? That would be the first place to look. There
may be slight differences in the gating of these signals at the drive.
 I wouldn't think that the index pulse would cause troubles but
you never know. On either drive, you should see index pulses.
 I'd have to dig out my manual to be able to help any more than that.
Dwight