dg@pallio.UUCP (David Goodenough) (07/12/90)
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 disks formatted by a good drive (of which I have several), can't be read by the bad drive. For those that are interested, the drives are made by Tandon, and use a split band actuator to move the heads. If you read this in comp.peripherals, please E-mail to the address below, since I don't get a feed of that group here on pallio. Thanks in advance, -- dg@pallio.UUCP - David Goodenough +---+ IHS | +-+-+ ..... !harvard!xait!pallio!dg +-+-+ | AKA: dg%pallio.uucp@xait.xerox.com +---+
mitch@harlie.UUCP (Mitch Mitchell) (07/14/90)
In article <XX000118c2@pallio.UUCP>, 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 >disks formatted by a good drive (of which I have several), can't be read >by the bad drive. For those that are interested, the drives are made by >Tandon, and use a split band actuator to move the heads. David - you might also want to check that the drive's rotational speed is up to spec. I had two 5 1/4" floppys that could format disks for themselves but no other drives could read them. I found that the rotational speed was off by about 5 milliseconds. It should be about 200ms between index pulses. Once adjusted (via a potentiometer on the circuit board) the drives worked fine. I used some diagnostic software that came with my computer but an o-scope or counter or mabe even seat-of-the-pants adjustment while trying to read a good disk would work... Good luck, Mitch ************************************************************************** * {uunet | texbell}!harlie!mitch Mitch Mitchell "Virago Rider" * * {uunet | texbell}!digi!mmitchel Voice & Phone Mail (214) 519-3257 * * mitch@harlie.lonestar.org FidoNet: 1:124/4115.224 * **************************************************************************
iisakkil@niksula.hut.fi (Mika R Iisakkila) (07/15/90)
In article <XX00000119@harlie.UUCP> mitch@harlie.UUCP (Mitch Mitchell) writes: > David - you might also want to check that the drive's rotational speed > is up to spec. ... > I used some diagnostic software that came with my computer but an > o-scope or counter or mabe even seat-of-the-pants adjustment while trying to > read a good disk would work... I too have an old full-height Tandon floppy drive. It has a 'stroboscope' pattern on this what-ever-it-is-in-English which spins on the bottom of the drive. Light it with a mains-operated light bulb and you can easily adjust the speed accurately enough.
del@fnx.UUCP (Dag Erik Lindberg) (07/20/90)
I already posted this once, but I think it crashed because of a non-existant group comp.peripherals... In article <XX000118c2@pallio.UUCP> 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?