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External HDD repair

Discussion in 'Troubleshooting and Repair' started by zenith, Oct 1, 2013.

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  1. zenith


    Nov 3, 2012
    I'm back after some help again. I have an external hard drive that I'm hoping to repair.

    When the supply is connected and the unit is switched on, the HDD does nothing,
    the LED doesn't light up.

    Its power supply is working and there is power to and from the switch.
    After the switch there is a P-Channel Logic Level Enhancement
    Mode Field Effect Transistor, a nikos P06P03LDG type.

    I found how to test it with the diode setting, negative probe to the source, touch the positive to the gate.
    When I do this I get a reading of 1985, which flashes up for a split second, then once I
    have moved the positive probe to the drain, I get a reading of 645, after touching the
    gate and source with my finger, I still get the same reading.

    the surface of the FET is pitted (looks like someone took sandpaper to the middle area of it)

    1) Would you think this is blown?

    2) It is a surface mount, can I replace it with a soldering iron?

    3) Could anyone recommend a decent UK supplier? for these and other components.

    The unit is about 5yrs old, and is a freecom classic sl.
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    A photo would confirm, but some not very reliable answers to your questions are:

    1) certainly could be.

    2) If you know what you're doing (large power devices soldered to a copper plane may require a pretty high power soldering iron though).

    3) RS

    But note that the failure of the mosfet may only be a symptom of the fault.
  3. goldfist


    Sep 18, 2013
    I'd just buy a replacement external hard drive enclosure and install the hard drive from the old external to the new external hard drive case. Depending on if you need IDE aka PATA or SATA they are pretty cheap. If you make a mistake with the drive powered while taking measurements you can damage your hard drive if you accidentally cross 12VDC over to a 5VDC circuit and lose your data on this hard drive by destroying its drive controller that is mounted to the hard drive itself.

    I have had a few external hard drives fail for this same reason and its best to replace the external enclosure than run the risk of destroying the drive that is powered off of it!

    Below is one that I purchased and it works well. They have cheaper no name brands available also that should work, but I have had good luck with Vantec enclosures for both 2.5" and 3.5" drives.
    Last edited: Oct 4, 2013
  4. zenith


    Nov 3, 2012
    Sorry for the delay in getting back to this,
    (*steve*) many thanks for the answers, the unit itself belonged to a friend of the wife,
    they have bought a new one now and left the old one with me, to play with.

    I managed to pick up the part locally and thought that since I had it I may as well try it, I did expect a bang, or maybe some smoke, but the unit has been running on my test pc now for over 24 hours :) lets hope it keeps on going.

    goldfist, thank you for replying,
    I have several external drives myself and if one dies, I do just buy another.The drive was removed as soon as I got it, just in case and I have a box full of old HDDs so it has an old 80g IDE one in now, should it go bang it wouldn't be any loss.
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Sorry zenith, I must have missed your posting earlier.

    Sounds like a good outcome. Congratulations.

    How was your experience at removing and replacing the surface mount mosfet?
  6. zenith


    Nov 3, 2012
    I have to confess (*steve*), I didn't even attempt it. I got someone else to do it. They have all the equipment and needed practice.
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