Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!entropy!dataio!shiloh!fnx!del From: del@fnx.UUCP (Dag Erik Lindberg) Newsgroups: comp.os.cpm Subject: Re: How do I align a disk drive? Message-ID: <592@fnx.UUCP> Date: 19 Jul 90 17:00:42 GMT References: Reply-To: del@fnx.UUCP (Dag Erik Lindberg) Organization: I/Ovations Kirkland, WA Lines: 49 I already posted this once, but I think it crashed because of a non-existant group comp.peripherals... In article dg@pallio.UUCP (David Goodenough) writes: >I recently got an old computer with a pair of full height 5.25" drives in >it. One of them is out of alignment because disks formatted in this drive >can't be read by the other (or any other 5.25" drive in the house), and Several people have recommended checking the drive rotational speed. Certainly try that first (I recommend using a flourescent light if there is a timing disk on the hub pulley underneath the drive). There will be a 10 turn potentiometer on the motor control board to adjust the speed of the motor. Don't adjust the wrong one if there is no separate motor control board. If you really need to align the drive, you will need an alignment diskette. This is a specially recorded analog diskette which cannot be duplicated by regular (digital) drives. You will also need an oscilloscope which can invert one channel and add the two channels together to produce a single trace on the screen. This is not 'x-y' mode, but a regular sweep mode with the two channels summed together. Connect the two probes to the differential inputs from the drive side 1 preamplifier and sync the sweep on the index pulse. Insert the alignment diskette, start the drive and step to track 16. Adjust your scope and you will see a pattern on the screen resembling a pair of cats eyes, or a butterfly if you prefer. The idea is to loosen the retaining screw on the stepper, and move the head until the two 'lobes' of the pattern are as close to the same height as possible. Tighten down the screw and make sure the pattern hasn't changed (this will probably take a few tries till you get the hang of it). Now unload the drive head so you can move the scope probes to the side 2 preamplifier and check the alignment of the other head. It is extremely rare that head 2 will be out of alignment with head 1, but if it is, you're in trouble. There is no good way to adjust head 2, as it is (usually) simply screwed to head 1 and you will have to remove the aligment diskette, make a blind adjustment, and take a reading to see if you hit the mark. If you feel like you want to go through with this, I can get you the part number for the alignment diskette. Heck, I might just send you mine, since I no longer feel it is cost effetive to align 5.25" drives. The whole procedure is likely to take you a couple of hours if it is your first time, and replacement drives can be had for $50. Incidently, if you buy an alignment diskette, it will cost you $35. -- del AKA Erik Lindberg uunet!pilchuck!fnx!del Who is John Galt?