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Hard drive motor

Discussion in 'Electronic Components' started by ehsjr, May 29, 2005.

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  1. ehsjr

    ehsjr Guest

    I was given an *old* CompaQ laptop with a bad hard drive.
    I pulled the drive, and intend to play with the motor,
    once I disassemble the drive. What kind of motor is it?
    What do I need to do to run it? The connection is much
    smaller than a regular hard drive, if that's any help.

    Ed
     
  2. Art

    Art Guest

    + 12 VDC, + 5 VDC, and a viable controller card with the imbedded EPROM, etc
    for that particular drive. Then have it connected to a motherboard or
    similar pcb that will provide the appropriate commands, either via a MPU or
    a programmed PIC. The motor itself will probably require a pulse width
    modulated DC voltage properly applied to the numerous coils.
     
  3. I've pulled apart doaens of 3.5" HDDs recently, just to get rid of all
    the old 0.5 GB clunkers around just taking up space. I was taking a few
    parts off the MB, but now I just scrounge the magnets, some phillips
    screws, and little else. Most of these drives are Maxtors. I've only
    pulled apart one 2.5" HDD. Here are some of my observations.

    There are just a few companies making the motors, one common one is
    NIDEC. Some motors are permanently glued into the drive case, and can't
    be removed as a unit. No matter if they're removable or not, they're a
    bitch to get apart because they're glued together.

    I see mostly four terminals on them, three for the phases and a common,
    so it might be seen as a 'Y' configuration. Some have a couple more
    terminals, apparently for a tachometer. I guess the four terminal ones
    use the output of a head to determine the speed, along with the head
    position.

    Older drives may have used a separate chip to drive the motor, but I
    think the trend has been to cram as much circuitry into a single chip as
    possible so that newer drives have the motor driver combined with many
    other functions. If so, then you'll have to roll your own to make the
    motor run.

    Many of the old Maxtors can be disassembled with a #1 phillips, but most
    of the newer and other drives require a #9 or #8 Torx and sometimes a
    smaller Torx. So you may have to swing by a hardware
    store and pick up a couple Torx bits for your changeable-tip magnetic
    screwdriver.

    I found the KSH210 which is on many MBs is a low Vce(sat) PNP transistor
    that works well for the B.O.s if you're willing to put up with the
    upside-down PNP config.

    I've found that the motors will light up the red LED connected across
    the coils very brightly. But it takes a quick spin to get the voltage
    high enough. Basically this proves that the motor has permanent
    magnets. I also connected a red LED across the drive terminals of the
    'voice coil' that drives the heads, and swinging it mack and forth will
    light up the LED brightly.

    Oh, one other thing. If you take off all four corners of the cover, and
    the cover doesn't pull off easily, then there's another screw or two
    hidden under the label that you have to remove. Poke around with the
    torx until you find it/them.

    Watch your fingers! Those super magnets can snap together with so much
    force that they'll pinch you.

    Have fun.
     
  4. ehsjr

    ehsjr Guest

    Thanks, Watson. Exactly as you described. Now for
    my next trick - I have 4 memory "sticks" (or whatever
    you call them) (modules ?) from an old 433 machine: 3
    with 128 mb and 1 with 64 mb. Do you know of any place
    I could donate them? They are going to the trash can
    (I hate that) unless I can find somone to give them to.
    You're good with salvaged parts, so I figure you might
    know. They are free to whomever wants them.

    Ed
     
  5. Donate them to Mike Terrell.
     
  6. WDino

    WDino Guest

    Most hard drive motors are of a synchronous type. That is they are a version of
    a stepper motor. So they need to be driven by a two phase ac signal.
     
  7. Of the many HDDs I've disassembled, most have motors made by NIDEC, and
    these have four terminals. I measured these and found that the
    resistances indicated three windings connected to a common terminal in a
    "Y" configuration. So it would need three phases to drive it.
     
  8. ehsjr

    ehsjr Guest

    Thanks! Mailed them to him today.
     
  9. ehsjr

    ehsjr Guest

    Mine is a delta configuration - 3 wires with 5 ohms between
    each wire. If I want to drive it, I'll have to come up
    with a 3 phase generator or use a PIC to come up with
    3 square waves, or ?

    Ed
     
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