Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!lll-winken!lll-lcc!ames!ncar!boulder!sunybcs!rutgers!att!mtuxo!mtgzz!drutx!druhi!dlm
From: dlm@druhi.ATT.COM (Dan Moore)
Newsgroups: comp.sys.atari.st
Subject: Re: Chinon Drive Speed Adjustment
Message-ID: <3696@druhi.ATT.COM>
Date: 30 Oct 88 19:04:10 GMT
Article-I.D.: druhi.3696
References: <8810281049.AA15598@ucbvax.Berkeley.EDU>
Organization: AT&T, Denver, CO
Lines: 40

in article <8810281049.AA15598@ucbvax.Berkeley.EDU>, MLS@s40.prime.COM says:
> 
> Help!  I just heard from my second "authorized Atari Service Center."  He
> concurs with the first that my drive passes all of the tests but doesn't
> work.
> 
> He admits that it is probably a speed problem, but claims that there is
> no way to adjust the speed on a Chinon model drive.
> 
> Is it possible that something this simple isn't adjustable?

	It's very possible.  There are a lot of 3.5" drives that you
can't adjust the drive speed on.  Most of the drives use a phase lock
loop (or whatever else they thought of) to keep the drive speed
constant.  They are calibrated when they are manufactured and after that
there is no easy way to change the speed.  (I don't think there is a
hard way either.)
	Atari buys really cheap drives and one of the ways the
manufacturer saves money is in the accuracy of their calibration.  

> For a simple speed problem, I don't want to spend the time or money to
> swap it if I don't have to.  Is the Chinon really as good as the other
> drives or did I get ripped off when I got it in exchange for my last one?

	Almost all the drives Atari has sold in the last year or two are
garbage.  The Chinon is no better or worse than the others.  Some of the
older drives (when the ST first shipped) were NEC's or Epson and were
very good but they cost too much.

	I wrote a drive speed test program when I was at Data Pacific.  It
used to be on a several of the commercial networks (CIS, Genie, Delphi).
You might try running it on your drive to see what the speed really is. 
Ideally it should be 300 RPM but anything from about 295 to 305 is ok
for standard formats.  Above 305 you would have problems with 10 sector
formats (eg. Twister) but the standard 9 sector format should work just
fine.

				Dan Moore
				AT&T Bell Labs
				Denver
				dlm@druhi.ATT.COM