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This article was posted to the Usenet group alt.hackers in 1995; any technical information is probably outdated.

Fixing 3 1/2" drive

Article: 8401 of alt.hackers
Newsgroups: alt.hackers
From: (Steven D Fairbairn)
Subject: Fixing 3 1/2" drive
Sender: (News Administrator)
Organization: Dept of Computing & Electrical Engineering, Heriot-Watt
University, Scotland
Date: Sun, 6 Aug 1995 15:02:00 GMT
Approved: Me
Lines: 39
Status: RO

Hope this works, anyway here's my

ObHack: Last Friday night I was archiving some pictures (The contents I'll
leave to your imagination ;) to disk. This was on my Amiga 1200. It involved
formatting the disks and then copying the pictures over. Suddenly whilst
formatting one of the disks it barfed and gave the message that it was
to format track 70". All right, I thought, it's just a bad disk so
I chucked
that one in the bin and then got the next disk. I formatted that one, but it
barfed at track 78 so now I was getting worried. I tried copying from a disk I
had already archived to but it had a read error in a file. I have an external
drive on my Amiga (It was the internal one that was playing up) so I tried it
in that drive, no problem, and I tried formatting a disk in it as well, no

Well obviously I wouldn't be stuck if the drive was broken but I didn't
want to have to buy a new internal drive. I took my 1200 apart and took out
the drive and popped the lid off. I assume that most people on this group
have seen inside a drive. I suspected that it was something to do with the
head moving mechanism as it was having problems above track 70. As you will
know if you've seen inside a drive, the head is moved by a worm gear which
is driven by a miniature stepper motor. Sure enough there was a whole load
of gunk at one end of the worm gear. So I cut up a little piece of J-Cloth
and used that to clean the gear. I then cut up another piece and put a spot
of oil on it and used this to lubricate the worm gear. I also lubricated
the little rod that the head assembly was attached to on the other side.
Well after this I connected the drive and tested it with the lid off. No
problems, you can hear a regular pulse as the head is moved for each track.
I tried reading from it, no problems either. So I put my Amiga back
together and did more testing, no problems. It's been fine since.

Ob-Hack2 This is a similar problem that my brother's CD player had. It was
jumping at roughly the same point on different CD's. This was a full sized
midi hi-fi system so when I took the case off it was mostly space inside.
Anyway I got to the CD mechanism and looked at the head mechanism. The
metal tracks that it moved along were scratched (badly in one or two
places) so I just lubricated them with oil. I put the hifi back together
and tested it, it was fine. It's worked fine since (about 2 years now).

Steven D Fairbairn.

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