Date   : Fri, 21 Mar 1986 00:05:12 GMT
From   : Philip Freidin <philip%amdcad.uucp@BRL.ARPA>
Subject: Re: Shugart Disk Drive Alignment

In article <813@well.UUCP>, tyger@well.UUCP (Richard A Childers) writes:
> 
> Hello, all, a question for those with knowledge and a willingness towards
> sharing it :

I'm silly enough to try and help

> 
> I have an old CP/M machine with the traditional Z80 and 64 kb RAM, and two
> floppy disk drives, Shugart 801's ... 8", SS/DD.
> 

so do I.  

> These drives are, over the ages, becoming less and less reliable. So far as
> I can tell, it's not a matter of hardware errors or anything, really, but
> I continually get these little TRAC errors. ( Which means that the head is
> not reading the track correctly, I believe. )
> 
Could also be a seek error. just needs some VERY light machine oil on the
guide rods.

> Now, from what I've read, it's quite common for your heads to drift from
> the original alignment, and it's a relatively small matter to re-align them
> if you have the appropriate devices to support your effort.
> 
> An oscilloscope, I have access to. What I need, I think, is a master disk,
> a metal diskette with master tracks, made out of metal, instead of floppy
> material - a hardware reference point by which the disk heads are aligned.
> The standard 77 track, 8 inch, single density IBM 3740/1D format for which
> these drives were made for.
> 

NO. The alignment disks (or "Analogue alignment disks" (same thing)) are
normal 8" floppy media, but with special info written on them.  Normal drive
electronics and controllers can't write this info.  These disk are usually
available from the major disk manufacturers such as Dysan, Memorex, Verbatim,
etc.  cost is about $50.

> I haven't really made a serious effort to look around for this, yet. I have
> reason to believe (a) that they are generally unavailable in all the best
> shops, as Shugart drives are basically as obsolete as skeleton keys, and
> (b) that the drive manufacturers made these special alignment disks mostly
> unavailable for the general public, to facilitate the existence of small
> repair shops and discourage people from doing their own maintenance.
> 
> Does anyone out there in net.land have any ideas on where I might find such
> a metallic master alignment diskette ? I'd be greatly appreciative, and so
> would thousands of others with similiar problems, since the 8" diskette is
> not yet dead, I suspect, and there must be others with a similiar problem ...
> 
> Thanks, awfully, lads and ladies ...
> 
> -- richard
> 

soooooo...

1) First check head stepping. I use DU or DUU to generate complex stepping
patterns, and then whatch for error messages, and also whatch the heads.

2) To do a re-alignment, you will need an analogue alignment disk, and a
dual channel scope (like a tek 465). The alignment disks come with instructions
for use. different tracks have different test patterns on them to facilitate
the various parts of the alignment process. Circuits for the drives can also
help

3) good luck.

4) If you need help, call me (408)737-8060 (after 7:00 pm)

       philip.


... Only a fool volunteers help....

philip @    ....{ how ever you get here }!decwrl!amdcad!philip