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From: monty@sagpd1.UUCP (Monty Saine)
Newsgroups: comp.sys.amiga.hardware,comp.sys.amiga.tech
Subject: Re: Realigning A1000 drives
Keywords: realign, drive
Message-ID: <983@sagpd1.UUCP>
Date: 11 Jan 91 16:19:54 GMT
References: <3876@bnr-rsc.UUCP>
Reply-To: monty@sagpd1.UUCP (Monty Saine)
Organization: Scientific Atlanta, Government Products Div, San Diego, CA
Lines: 29

In article <3876@bnr-rsc.UUCP> uunet!chekov!hounsell writes:
>  Now, I've called two places around here to determine if the drive could be
>realigned, and was told that it was too difficult to do, and that they always
>replaced the units. One store quoted me $150 for the internal drive unit, and
>another $300! So, is there any PD software for drive alignment? Can it even be
>done? How would I do it (assuming access to an oscilloscope, if required)?

    To realign a drive requires an alignment disk and an o'scope. The hard 
    part is finding the alignment disk. They usually run about $100 and do
    to there nature you can't 'pirate' one. Some of the tracks are physically
    skewed on the disk in the form of a sine wave so that when the heads read
    them they form a lissajous pattern. When you look at the two side of the
    differential output from the heads you get equal but 180 degree out
    of phase sine wave when the head is centered over the track. It is
    also necessary to have a test fixture or software that allows you to step 
    to a certain track and stay there.	It also is necessary to know where
    on the drive to pick up the amplified head signals so that you don't load
    them down and affect the readings.

    This is all assuming that the drive manufacturer has left some means of 
    changing the alignment without special tools.o

    If you are going to do a lot of these, the disk is the way to go, but
    most of us have found that it is cheaper to purchase a new drive. Most
    IBM type 720k drives function eletrically in a A1000, it just becomes
    a case of creative physical mounting and asthetics.

    Good Luck
    Monty Saine