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CD-R/W drive spindle clamp magnet catastrophic failure.

Discussion in 'Electronic Repair' started by [email protected], Sep 27, 2005.

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  1. Guest

    Well it is pretty catastrophic to me ;-)

    I have an ASUS CRW-4012a that has been working great for years now, and
    has recently started to have "issues" seeing a disk in the drive and it
    started making noise, (the kind of sound that makes you think a plastic
    disk is slipping and there is friction noise from it).

    Since it is no longer covered by the manufacturer warranty, I decided
    to take it apart and see what was going on.

    At first I couldn't figure out what could be wrong as all the motors
    seem to operate normally, and the gears are intact. There was a bit of
    dust, but I cleaned that out and re-lubed the stepper gear as well as
    the rails the head travels on. I then started to focus on the clamping
    mechanism. Typically what I have seen in the past is on the spindle
    there is a magnet of some type attached (screwed or glued), in this
    units case, there was what I identified as a magnet, but parts of it
    were shiny (hardly any) and other parts were rather black, like as if
    it had some funky gunk on it. I went to wipe it off and discovered the
    funky stuff was the magnet.

    It would appear that this (and I guess many now) magnet is made by
    taking a ferrite magnetic powder and encasing it with a layer what
    looks like chrome. The problem appears to be that the outer shell wore
    away somehow or was damaged at some point (more likely they knew it
    would die after a couple years and people would just buy entire new
    drives) and then we only had loose magnetic particles trying to pull
    down the upper platter of the clamp and spin it. That explains the
    noise and it's failure to spin up properly (especially at 40x).

    After cleaning some of the material that had been thrown onto the few
    metallic parts in the unit I was able to verify the drive is still
    functional, but I need to replace the clamping magnet.

    Does anyone have any idea where I might find a non powdered replacement
    or what I should look for?
  2. Dave D

    Dave D Guest

    You probably don't want to hear this, but my advice- bin the drive and buy a
    new one. They're not exactly one of the more expensive PC parts, and if it's
    years old there'll likely be other parts near the end of their life. You can
    get a dual layer DVD writer now for far less than a CDRW of that vintage
    would have cost. You might find a similar magnet in a scrap drive, but is it
    really worth the bother?

  3. James Sweet

    James Sweet Guest

    My advice is to look for a dead drive and salvage the clamp from that, it's
    not gonna be worth buying a new part.
  4. Dean B.

    Dean B. Guest

    Hello your description of the magnet, it sounds like a
    Neodymium or "rare earth" magnet.
    These are usually coated in "chrome" and if you chip the coating away the
    underlying magnet has a "powdered" look
    to it. These have now become VERY common and you should be able to find a
    suitable replacement. Do a search for
    "rare earth magnet" on the net and I'm sure you'll find some place in your
    city that carries them. I live in Canada
    and a place called "Lee Valley Tools" has them in various sizes and shapes
    for a dollar or two each. The smallest they
    carry is a mere 1/4" in Diameter by 1/8" thick !

    Good luck......Dean.
  5. Mike Berger

    Mike Berger Guest

    The magnets are made that way because they can't get the same
    strength out a rigid material in that size for the same price.
    You probably won't find a harder replacement that will fit.

    I doubt they made them fail intentionally. Those magnets
    don't fall apart of their own accord, but hard contact will
    break them.
  6. Guest

    I'd rather not replace it with a DVD writer as I already have one. I
    like to have a decent 40x CD-ROM for games and burning CD media saves
    wear and tear on the DVD drive.
    I also enjoy troubleshooting/fixing things, so I thought it was worth
  7. Dave D

    Dave D Guest

    Me too! However, I don't spend more than about ten minutes on CD Roms these
    days though, I quickly discovered most failures are not worth the time and

    Always worth asking. Good luck with the repair.

  8. Guest

    The strange thing is this is almost my youngest drive in the house. All
    my significantly older/slower ones still truck along, and my other 40x
    units (different manufacturer) seem to be fine. I have not mistreated
    it so I can only assume the drive/loading mechanism must have somehow
    been causing damage to it.

    As for intentional design flaws, that is just my cynical side saying
    the worst about corporate thinking. I know a lot of gamers and they
    would just toss a drive (or other component) that quit working and buy
    another, even if it was easily repairable. Back when that stolen
    electrolyte formula was in heavy use I managed to get quite a few
    motherboards to fix due to this mindset. Speaking of intentionally bad
    design, those gateway lunch boxes that have only a sleeve fan in the
    power supply are quite evil. I just finished repairing 6 for a
    preschool, new caps all around and real bearing fans put in the power
    supplies. IMO there is no way that bad of a design was accidental.
  9. Guest

    Thanks you (all of you) for your replys. When I was starting to look I
    ran across a TDK PDF file talking about the product the magnetics
    division made and things they are used for. From what I could tell they
    have 3 types they make for drive clamping in the ferrite dry
    anisotropic type (formula is SrO6Fe2O3) parts FB5D, FB3N and FB3G.
    Shape according to them was called DH (I'm guessing for doughnut hole).

    I'm going to cannibalize my 1 dead drive (a DVD/CD-R combo) that
    overheated and see what I can do, and then check on what I can find
    based on what you suggested.
  10. spudnuty

    spudnuty Guest

    Don't know about the clamping magnets but simular magnets in pager
    motors and other motors indoor flyers use have had that same issue.
    They are formed rare earths with chrome overcoating and they all fail
    in the same manner. The crome just flakes off and jams the motors. It
    must be a manufacturing problem. If you posted pics and dimenslions we
    all have lots of junked CD-ROM drives that we could send you a simular
  11. James Sweet

    James Sweet Guest

    Aren't most DVD writers faster than that? My CD-RW drive is 52X and was
    under 50 bucks several years ago. By all means, try to fix what you have,
    but I really wouldn't worry about wear and tear on a DVD writer, they're
    well under 100 bucks now and will likely be obsolete long before it wears
  12. Maybe now, but a year-and-a-half ago, one of the selling points of the
    Lite-On drive I bought was that, unlike other brands, similar (to
    CD-RW) CD performance was possible.

  13. Franc Zabkar

    Franc Zabkar Guest

    I'd be wary of replacing just the magnet. Balancing could be a big

    -- Franc Zabkar

    Please remove one 'i' from my address when replying by email.
  14. spudnuty

    spudnuty Guest

    I'm thinking "replace the whole thing".
    I also just repaired a Daewoo DVD player that had a balance problem in
    the clamping assembly. The assembly was not completely snapped
    together. It had either come unsnapped or was never snapped completely
    in assembly. It was so bad that you could feel the vibration when the
    unit spun up. The client said it just wouldn't read some DVDs
  15. Mike Berger

    Mike Berger Guest

    The doughnut shaped ones are not hard to balance.
  16. Andy Cuffe

    Andy Cuffe Guest

    I would look for a scrap CD-ROM drive and use the entire clamping
    assembly if you can.
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
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