[sebhc] Z37 Diag

[Barry Watzman]

Track 0 is a signal from the drive to the controller that the head of the
disk drive is in the track 0 position.  It comes directly from an optical
sensor (LED and photocell, when the drive gets to track 0, a blade on the
head mechanism blocks the light beam from the LED so that it never reaches
the photocell).

[==> On some drives, the photocell signal is "ANDed" with one phase of the
stepper motor.  The purpose of this is to prevent track -1 and track -2 from
also producing a valid track 0 signal (yes, this really happens and, as one
who has experienced it, it can cause real problems).  But this is more
common on 8" drives, my recollection is that 5.25" drives don't usually do
this.  But 96tpi 5.25" drives are more likely to do this than 48tpi drives.]

The track 0 signal is a pure DC signal, and you should be able to "enable"
it manually (by sticking a piece of paper or other material into the sensor)
unless your drive does the stepper motor "and".  Once you have track 0 FROM
THE CURRENTLY SELECTED DRIVE, tracing it back through the controller should
be a simple matter of checking DC voltage levels with a multi-meter.


-----Original Message-----
From: sebhc-bounces at sebhc.org [mailto:sebhc-bounces at sebhc.org] On Behalf Of
Mark Garlanger
Sent: Saturday, July 29, 2006 11:35 PM
To: sebhc
Subject: [sebhc] Z37 Diag

It's me and my (never ending) computer problems again (you guys are probably
getting tired of these ;-)  )

So, I got my H17-3 cleaned up, loaded with high-density drives, and
connected
to my 'questionable' soft-sectored controller.

I had received the Z37 diag disks (both hard & soft-sectored versions)
a little while
ago, but didn't realize what they were since they came with CP/M
2.2.04 distribution
disks and diag disks were labeled: "CP/M 2.2.04 Diagnostics & conversion"
with
no mention of Z37 or soft-sectored.

I booted the hard-sectored version of the diag disk since the soft-sectored
version would not boot (nor any of the soft-sect CP/M dist. disks).
It starts up with
    "ZENITH DATA SYSTEMS Z37 SUPPORT SYSTEM"
Options include 1. Disk controller checkout, and
2. General drive/controller diagnostic.

Choosing option one - First it checks to see if the motors
are all spinning.. and that is fine.
Then it checks the drive select. That is also fine.

Then it gets to:
"VERIFYING HEAD POSITIONING SYSTEM. STAND BY..."

Displays the following error:
"NO TRACK ZERO INDICATION. CHECK HEAD MOVEMENT
AND INDICATOR OPERATION."

The manual provides this excellent piece of advance:
"If you receive this error, call Heath or Zenith Technical Consultation for
assistance."

Great advance in the mid-80s, not much help now ;-)

Even with that failure, I tried option 2, it didn't even get to the second
menu which is shown in the manual. When I select any of the three drives,
the proper drive light goes on for a little bit, prints "ERROR -" then
hard-sectored drive come back on and the system locks up.

This just may be failing with the same head positioning problem of the
first test.
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