24 Apr
2005
24 Apr
'05
9:06 p.m.
Subject: Re: my Data General Nova 4/X, disk woes continue
From: John Lawson <jpl15 at panix.com>
Date: Sun, 24 Apr 2005 20:19:22 -0400 (EDT)
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Cc: "General Discussion: On-Topic Posts Only" <cctech at
classiccmp.org>
On Sun, 24 Apr 2005, Tom Jennings wrote:
I'd forgotten that little bugger. It thats the case use a different
pack for testing afterwards. sometimes the curd on the head damages
the pack.
Allison
After warm-up, it's worse. Signals all through the path look
OK, hot and cold. I can see no difference, but this is 10 MHz
NRZ data, in a two-state amp with AGC. I think I'm screwed.
Um, scrub the heads real good again? Murphy may have been a lot of
things, but subtle wasn't one of them....
Cheers
John 
24 Apr
24 Apr
9:57 p.m.
> Um, scrub the heads real good again? Murphy may
have been a lot of
> things, but subtle wasn't one of them....
>
> Cheers
> John
On Sun, 24 Apr 2005, Allison wrote:
I'd forgotten that little bugger. It thats the
case use a different
pack for testing afterwards. sometimes the curd on the head damages
the pack.
Well, less than a dozen hours since the last cleaning...
25 Apr
25 Apr
1:02 a.m.
On Sun, 24 Apr 2005, John Lawson wrote:
Drives / packs have been sitting where? for how long?
and the System is now
operating where?
Enquiring minds....
Well, I keep it outside. It got wet, but when I turned it on it
made a lot of sparks and got hot, so I figured that would dry it
out?
Actually, it's in my lab. Has a dehumidifier, temp hasn't dropped
below 60. Papers, fine electronics, machine tools, media and
paper seem happy there.
I honestly don't think it's a media problem. Late Feb/early Mar I
formatted it, and ran it for many hours, with zero defects and no
runtime errors. Plus, the errors are scattered over the disk(1)
and developed all at once. They happen on all four surfaces. The
commonality to all heads made me think R/W electronics, but of
course servo fluctuation or other problem could do that.
I suppose I could remove a head for close examination but I just
don't think all four surfaces got dirty all at once. Head crash
problems are audible!
1:05 p.m.
<snip>
I suppose I could remove a head for close examination but I just
don't think all four surfaces got dirty all at once. Head crash
problems are audible!
The other thing you mentioned but didn't comment on the condition of is
the grating and the optical sensor for said. are they clean? also, on
the drive's we had, of the western dynex and microdata variety, you
could physically feel the drive or the voice coil and feel it vibrating
when there was a servo problem, in most cases, or hear a difference
in the seeks as it failed.
Jim
4:53 p.m.
On Mon, 25 Apr 2005, jim stephens wrote:
The other thing you mentioned but didn't comment
on the condition of is
the grating and the optical sensor for said. are they clean? also, on
the drive's we had, of the western dynex and microdata variety, you
could physically feel the drive or the voice coil and feel it vibrating
when there was a servo problem, in most cases, or hear a difference
in the seeks as it failed.
It's pretty clean; I have not touched it. I can RTFM on cleaning
it, but the drive was very clean to begin with.
If there's a servo problem it's pretty subtle. I'm talking 10%
error rate (or whatever) not 100%. Mostly it reports in higher
cylinder numbers. This isn't a go/nogo problem -- I wish!
I will however stare at it and look for bulk odd behavior first.
I'm sure there's an error voltage off the servo I can look at, as
well as other nice closed-loop thingies. The documentation is
excellent, it has huge waveform diagrams and state diagrams (flow
charts).
8:51 p.m.
I was always counciled never to ever touch the reticules, or the
sensors, unless something dirtied them. And then in the field,
replace them if that was the case. There was no recommended
way to clean them then. Now you have to try.
At microdata, the material used to make the image on the reticules
was not something I was ever told, and for both the dynex, and
the microdata drives, they were supposedly the same. I'd be
very very nervous to touch them.
I did see one case though where there was strange things across
all heads.
You have gotten good suggestions from about everyone else on
most the rest I would suggest.
hope you sort them out. I have a few Microdata 9000's which are
5+5 that I will want to fire off sometime, so I am watching your
experience with great interest. Thanks for such a detailed description.
jim
Tom Jennings wrote:
On Mon, 25 Apr 2005, jim stephens wrote:
26 Apr
26 Apr
12:48 a.m.
On Mon, 25 Apr 2005, jim stephens wrote:
I was always counciled never to ever touch the
reticules, or the
sensors, unless something dirtied them. And then in the field,
replace them if that was the case. There was no recommended
way to clean them then. Now you have to try.
It's clear from the way they work these are extremely touchy.
I'll RTFM before I do anything, though I won't dwell on this, I
don't think it's the problem.
At microdata, the material used to make the image on
the reticules
was not something I was ever told,
I belive the DG manuals say the mystery material is "glass" :-)
Makes sense. Hard, flat, stable, cheap.
7023
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ajp166＠bellatlantic.net -
jpl15＠panix.com -
jwstephens＠msm.umr.edu -
tomj＠wps.com