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MFM controller cards

Discussion in 'Electronic Repair' started by [email protected], Feb 25, 2007.

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  1. Guest

    I need to find at least one MFM HDD/floppy controller card to try to
    get into my old system. My billing files and some other programs which
    I would like to back up are on on these drives. I think my controller
    failed. I could really use another of these drives if anyone has one
    also but if not I would be happy just to find a controller board
    initially. I'm running two Seagate St251 drives. I've looked just
    about everywhere for these things. If anyone has any of this old
    stuff lying around they don't need and would like to sell, (or part
    with, or whatever), please let me know. I would be very grateful.
    Thank you. Lenny Stein, Barlen Electronics.
     
  2. James Sweet

    James Sweet Guest


    I just did an ebay search and came up with more than 30 various MFM
    controllers, most are pretty cheap.
     
  3. Ask your local computer recycler to look out for one for you.

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  4. JANA

    JANA Guest

    You may be able to find a MFM controller, but it may not work with any of
    the mother boards past the 368 or 486 era.

    As for the new mother boards, the expansion slots would not be compatible,
    and also the BIOS may not see the MFM controller.

    What I would do, is get an older working computer that has MFM drive
    support, and put everything to floppies to transfer it across. Networking a
    very old dos computer to a Windows based computer may not be worth the
    effort.

    I would be curious to know why you did not have everything backed up on
    floppies or something in the first place?

    --

    JANA
    _____


    I need to find at least one MFM HDD/floppy controller card to try to
    get into my old system. My billing files and some other programs which
    I would like to back up are on on these drives. I think my controller
    failed. I could really use another of these drives if anyone has one
    also but if not I would be happy just to find a controller board
    initially. I'm running two Seagate St251 drives. I've looked just
    about everywhere for these things. If anyone has any of this old
    stuff lying around they don't need and would like to sell, (or part
    with, or whatever), please let me know. I would be very grateful.
    Thank you. Lenny Stein, Barlen Electronics.
     
  5. Rick

    Rick Guest

    Before you buy, why do you think the controller has gone bad? In a
    system old enough to use MFM drives there could be a lot of reasons for
    a problem. What's the system doing or not doing? Any POST error codes?

    Have you tried the obvious first? Pulled the conroller card, cleaned the
    card contacts and reseated the drive cables? You may want to clean the
    contacts on the drives too - considering they use card edge connectors.

    Rick
     
  6. Hi!
    Good points, all of them. Checking to be sure that the system's CMOS battery
    is still running would be an excellent idea. After years of sitting it could
    be dead or depleted. (Many older motherboards used a rechargeable NiCad
    "accordion pack" battery.) If yours has a battery like this, leaving the
    system powered on overnight might bring it back up. They do seem to be
    pretty robust.
    Be ***very*** careful if you do this! If you can help it, do *not* remove
    those hard drives from the system unit. ST-251 drives have stepper motor
    head actuators that are subject to falling out of calibration with the
    information stored on the drive platters if the operating temperature range
    changes or the drive is removed and reinstalled. There are only two ways out
    of this if you get the drives working--either hope that you can find the
    right climate/installation "sweet spot" or low-level formatting. Low level
    formatting will destroy all data on the drives.

    William
     
  7. Can you cite a reference? In my experience, MFM drives are about the
    most robust things on the Planet. :) The tracks are so far apart that
    normal temperature changes have no effect. I have some ST-251s (I think
    that is the model) sitting at the bottom of a closet. I bet if I could
    find a system today to power them up, they would work just as well as
    20 years ago (if the grease hasn't congealed).

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  8. Ken Weitzel

    Ken Weitzel Guest

    Hi...

    Anyone else remember "stiction" ?

    Take care.

    Ken
     
  9. Sure. It started out on 40meg Quantum brand 3.5inch SCSI drives. Due to the
    quickly changing technology, Quantum got as far as the LPS (Low power) 105 meg
    drives before they found out about the problem and replaced the grease.

    I've heard of a few 20 meg drives having it, but have never seen one.

    Where there other manufacuters?

    As far as I know, it never affected MFM/RLL/IDE drives.

    That was in the early 1990's. By now, most drives of that age of any
    type and manufacturer may be afflicted by it.

    Geoff.
     
  10. Jeroni Paul

    Jeroni Paul Guest

    I agree, I've a few of them, WD 20Mb and a Kalok 40 Mb with Win3.11,
    no defective sectors.
    These disks never die.
     
  11. Rick

    Rick Guest

    That's not the way I understand the technical problem. Physical removal
    of the drive doesn't do anything. It's actually operation of the drive
    that can eventually cause problems. Considering how much heat these
    drives generate during operation simple temperature changes from
    removal/reinstallation aren't going to cause the problem.

    Because the stepper motors aren't all that accurate for head placement,
    over time data is written not quite exactly in the same position on the
    physical tracks. If the variance is bad enough over time you can start
    getting "sector not found" errors and the like if the write position for
    the data gets too far out of alignment with the servo tracks. It can
    start crapping out the servo tracks in the process - making head
    placement impossible.

    The cure is to just perform a low level format on MFM drives with
    stepper motor head actuators every few years as part of routine
    maintenance, rather than wait for read or write errors to start
    happening. And, of course, back it up and make sure you have a reliable
    restore procedure before doing this.

    The problem does not apply to MFM drives with voice coil head actuators.

    Rick
     
  12. Franc Zabkar

    Franc Zabkar Guest

    The following article suggests that stiction is a problem that first
    appeared in 3.5" drives.

    http://en.wikipedia.org/wiki/Stiction#Stiction_and_computer_maintenance

    "In the context of hard disk drives, stiction refers to the tendency
    of read/write heads to stick to the platters, preventing the disk from
    spinning up and possibly causing physical damage to the media. Some
    hard drives avoid the problem by not resting the heads on the
    recording surfaces.

    Stiction is also known to cause read/write heads to stick the platters
    of the hard drive due to the breakdown of lubricants which coat the
    platters themselves. In the late 1980s and early 1990s as the size of
    hard drive platters decreased from the older 8" and 5.25" sizes to
    3.5" and smaller, manufacturers continued to use the same calendering
    processes and lubricants that they had used on the older, larger
    drives. The much tighter space caused much higher internal operating
    temperatures in these newer smaller drives, often leading to an
    accelerated breakdown of the surface lubricants into their much
    stickier components."

    - Franc Zabkar
     
  13. Yep, been there done that. :) A good whack on one corner was one method!

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  14. If you want a gentler solution, spin the drive on its axis before
    booting up. I had a Zenith portable that had stiction and that solution
    worked every time.

    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
     
  15. James Sweet

    James Sweet Guest

    I used to have a 286 with one of those, I used it for years after
    removing the cover to break free stiction so it would spin up and it
    never failed.

    Unfortunately the similar 30MB RLL drive in my PC/XT died, I dragged it
    out of long term storage in my mom's shed and it makes some unhealthy
    noises and won't boot :(
     
  16. James Sweet

    James Sweet Guest


    Stiction was caused by the read/write heads getting stuck to the disk
    surface. For years I had an open 20MB Seagate SCSI drive sitting on my
    bookshelf, one day I rotated the platter by hand and it ripped a couple
    of the heads right off the arms, they were stuck quite firmly to the
    disc. Oops!
     
  17. clifto

    clifto Guest

    I also remember (but never tried) the idea of putting the drive in the
    freezer for a while in a plastic bag and letting the temperature change
    do the work. (The plastic bag was to reduce condensation on the drive
    itself.)
     
  18. clifto

    clifto Guest

    You're sure it was MFM? The 251's were often used with RLL controllers.
     
  19. James Sweet

    James Sweet Guest


    People often "cheated" and used MFM drives with RLL controllers, but the
    ST-251 was designed as a 40MB MFM hard drive. It was original equipment
    in the IBM AT.
     
  20. 'Often used' are the key words here, the 251's were MFM but worked fine with an
    RLL controller thus acquiring a bit more storage space.

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    Australia isn't "down under", it's "off to one side"!


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