Needed: 1 IBM 8" alignment disk. - test-drb@ccmp.vtda.org

29 Nov 1999

-----Original Message-----
From: CLASSICCMP(a)trailing-edge.com &lt;CLASSICCMP(a)trailing-edge.com&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Monday, November 29, 1999 8:36 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.

...
 John B. wrote:

 P.S. The sooner the better.. this thing is eating
original IBM software
diskettes from the early '70s 
Dick wrote:

 Having aligned about 25 8" drives over the
last 6 months, I can tell you
that if your drive is "eating" your diskettes, the problem isn't with
alignment. 
It depends on the rate of "eating", but for 25-year old floppies it's
not unusual to have a fair bit of flaking of the emulsion on the head
(lower) side.  If there's any damage on the *top* side, that's definitely
the head load pad. 
Again, "eating" refers to the fact that when I try to write it is damaging
the format through the writing process thereby destorying more original IBM
software... It is a very clean drive and handles disks well.. (it just
doesn't find sectors most of the time)...

It isn't alignment as I can manually move the head very slightly back and
forth which does affect the data coming into the controller assembly but
does not help it find the actual sector... Therefore, hardware or an anlog
adjustment

I would like an alignment disk so I can use "their" tuning procedure to make
this drive work quickly. It has a number of adjustments including : Clock,
window, gap, etc...

 I would know what to expect (data wise) as I am troubleshooting the boards.

PROBLEMS TO DATE:
Cold solder joints on the backplane... yuck! Resoldered the whole thing just
to get the drive to talk to the CPU... I expect 1 or 2 problems on the
boards which are keeping this drive from running nicely.

I try to restore things that are pre-8" but this drive was built for a
Straight-8,8/S so I *have* to get it going.

john

PDP-8 and other rare mini computers

http://www.pdp8.com

...

Tim.