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Thread: Aligning Floppy Drives

  1. #21
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    So what's the absolute minimum for a floppy alignment scope? I'm wondering about this mostly for those folks who have no desire to shell out for a regular DSO, much less know how to use one.

    Could, for instance, one use a stm32f103 "Maple Mini" (or clone) board to do the job? That's an outlay of what, $5? The signal levels are known; a floppy drive is a comparatively slow-speed device...you get my drift.

  2. #22

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    Quote Originally Posted by Chuck(G) View Post
    So what's the absolute minimum for a floppy alignment scope? I'm wondering about this mostly for those folks who have no desire to shell out for a regular DSO, much less know how to use one.
    Chuck,

    EXACTLY! You have articulated the problem perfectly. Now we just need a solution !
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions MatchPoint AND/OR UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!

  3. #23
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    I've got a small pile of the boards not doing anything in particular; I may just give it a try and see what happens. Don't be in a hurry, though. I've got some fooling with ESP8266 stuff to work on first.

  4. #24

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    There is a specification for the first track at the edge of a floppy. If one had a clean disk, some of the magnaflux fluid and a microscope with a measuring stage, one could set up their drive. Once setup one could make their own alignment disk.
    I don't know why you'd need a storage scope to do such alignment?
    Dwight

  5. #25
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    Quote Originally Posted by Shadow Lord View Post
    The Rigol looks like a very nice piece of machinery. Chuck had also mentioned them at the beginning of the thread. Of course it is significantly more then the used HP and frankly I think it may just be too much scope for me.
    I have both an Rigol 1052E and a 1054Z. I'm pretty happy with the 1054Z, and I was happy with the 1052E back when it was current. While there are a lot of bells and whistles, you shouldn't feel that you need them in order to justify the scope. Four channels, that time you do need it, is way more convenient than two channels. IMO it's generally important that you get one that has an intensity gradient display (i.e. the 1054Z). This gives you analog-like visuals on a digital scope. Check out the eevblog videos for more information than you'll ever want to know about oscilloscopes, that's what sealed the the decision for me on upgrading from 1052E to 1054Z. Also lots of handy tips over there on how to properly use a scope for those of us who might not have formal training.

  6. #26
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    Quote Originally Posted by Dwight Elvey View Post
    There is a specification for the first track at the edge of a floppy. If one had a clean disk, some of the magnaflux fluid and a microscope with a measuring stage, one could set up their drive. Once setup one could make their own alignment disk.
    I suppose--note that an "adequate" alignment on a 360K is generally considered to be in the <1 mil area,

    What's probably more useful for the neophyte is the "digital" alignment disk, where tracks have sectors located at various offsets from "center". Basically, you use a "READ ID" program that runs continuously until you get the center IDs and a certain number on either side of ideal reading error free. You don't even have to remove the drive if you can get to the stepper adjustment.

    It shouldn't be difficult to modify a drive to produce this thing--just modify the hub to clamp off-center.

    It's a thought, anyway.

  7. #27

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    Quote Originally Posted by Chuck(G) View Post
    I've got a small pile of the boards not doing anything in particular; I may just give it a try and see what happens. Don't be in a hurry, though. I've got some fooling with ESP8266 stuff to work on first.
    Chuck,

    Do we really need to reinvent the wheel here? I mean if the kit is $5 and it needs soldering work plus you need to buy probes then a readily available cheapy scope maybe better? I think the first thing would be to define minimum specs for a scope to align drives: e.g. number of channels, digital w/ how much memory, absolute function/features needed, frequencies, etc. Then at the very least if people can find a scope that meets those requirements (say at recyclers, goodwill, junk shop) they are good to go.

    Of course having a homebrew scope would be nice and probably much more educational but like you said that may take a while.

    BTW: I am wondering if you know what the Accurite Drive Probe Advanced Edition was? I know it was their SW mixed with HW. I am guessing it was a special FDC and break out box that let you do accurate track stepping and seeks to use with their HRD disks but I could be wrong. They haven't sold it in the past five years (last time I inquired) and I have never seen it come up on the secondary market.
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions MatchPoint AND/OR UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!

  8. #28
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    If you need a 'scope
    Use whatever floats your boat.

    One thing that Dwight's "optical" method won't accomplish is the determination of head azimuth, but I suspect most people aren't interested in that.

    My thought was that the F103 boards having some intelligence might make it easier if they were tailored to the task at hand.

    Accurite didn't invent the Drive Probe method--Dysan was selling 8" digital alignment disks long before the Accurite or AlignIt stuff came out. I've got one, complete with Z80 CP/M code to provide readouts. On 5.25" and 8" drives, a large degree of success depends on your steadiness of hands--changing the alignment by a couple of mills is usually a very small adjustment. So the digital alignment disks are eminently suited to the hobbyist. (FWIW, the track spacing on a 77-track 8" drive is exactly the same as that on a "360K" 5.25" drive. Most 3.5" drives space tracks at about 135 to the inch).

    If you want something fancier, you create your own alignment disks the way we did back in the day. We took a Micropolis 100 tpi floppy drive, mounted it on a 3/4' thick aluminum slab and gutted the innards of the leadscrew stepper and coupled the rear of the stepper shaft to a 100:1 precision reduction gear, driven by an external stepper, with a dial indicator to locate track 0 exactly. Micropolis was known for its precision-ground leadscrew arrangement--this is also what drove them out of the floppy market--leadscrew positioners are much more expensive to manufacture and also somewhat slower in 5.25" drives than taut-band models.

    We made our own alignment floppies. We discussed being able to vary the azimuth of the head as well, but never got around to implementing that.

  9. #29

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    Quote Originally Posted by Chuck(G) View Post
    Accurite didn't invent the Drive Probe method--Dysan was selling 8" digital alignment disks long before the Accurite or AlignIt stuff came out.
    That I am aware of. However, I always wondered what the HW portion of their kit did that justified them asking an extra $800 for it (vs. plain SW).
    Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions MatchPoint AND/OR UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!

  10. #30
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    Dunno--I've used AlignIt from time to time and it's a very professional package--after running all of the adjustments, the drive is re-tested and a full report is printed out--and the data for that particular drive is stored in a database.

    Most of my issues stem not from having drives that are properly aligned, but getting floppies from clients that were written with drives that are way out of whack. There, a drive is "un-aligned" so the floppy can be read.

    On some of the cheaper WP systems, it's really surprising how far out a drive can get.

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