RK05 alignment - without alignment pack?

Tom Gardner thomas.gardner at sbcglobal.net
Mon Dec 14 12:06:34 CST 2009

> Date: Sun, 13 Dec 2009 19:04:11 +0100
> From: Philipp Hachtmann <hachti at hachti.de>
> Subject: Re: RK05 alignment - without alignment pack?
> To: General Discussion: On-Topic and Off-Topic Posts
> 	<cctalk at classiccmp.org>
> Message-ID: <4B252C9B.1010100 at hachti.de>
> Content-Type: text/plain; charset=ISO-8859-15; format=flowed
> Hi Tony,
> thanks for the reply.
> >
> >> The RK05 manual tells me how easy it is to realign the heads: Just load
> the alignment pack and...
> >> -- But I don't have an alignment pack :-(
> >>
> >> Does anybody (best would be in Europe) have an RK05 alignment pack I
> could use?
> >
> > I have one, but there's no way I am trusting it to the postal 'service'
> Hm. I can understand that...
> >> Is there a known trick to do it without alignment pack? I have working
> drives and formatted disks handy.
> > 3) With a 'scope connected to the read amplifer testpoints (as if doing
> > the alignment with the pack) and the positioner set to cylinder 0, screw
> > in the appropriate  algnment screw. You'll see the singal amplitude rise
> > as the ehad gets over the data track, and then fall off as you go past
> it.
> How does the positioner find track 0?!?
> Does it use the end of range microswitch and then count? This is a bit
> unclear to me.
With a working servo, the servo will move the carriage to what the optical
transducer calls Track 00, but where the heads are with respect to the
tracks in the disk pack is a matter of alignment, which was lost when the
scale fell off and was re-attached.  The heads could be anyplace, plus or
minus many tracks of Track 00.

There is not likely to be any information recorded towards the outer
diameter from TK00 (maybe some residual unerased junk).  If you can
prerecord your test pack on a good drive with alternating patterns of 1F and
2F starting at TK00, say 1F for all sectors on TK00, 2F for all sectors on
TK01, etc. for a few tracks, then it should be obvious where the pattern
stops repeating as you manually move the heads in and out.  The last good
track as you move out is TK00.  BTW, I say this assuming DEC didn't put some
reserved tracks towards the outer diameter from TK00.  Today the logical
TK00 (or block 0000) is not at the outer diameter, but I suspect this is not
so for the RK05.


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