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  1. Member
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    I've been archiving my Mini-DV tape library, and just bought a new 2TB hard drive to fit more videos. And just before putting the new hard drive in the PC--I set the drive in its foil bag on top the plastic bin full of camcorder tapes.

    Yes, I'm aware that hard drives have gigantic super powerful magnets in them. I had a hard drive magnet on my fridge, once you stuck it on, you had to slide it off sideways because it couldn't be pulled straight off. Nevertheless, I completely forgot about this, and I'm horrified by my incompetence.

    About a quarter of my collection hasn't been captured yet.

    Symptoms:
    Most won't play at all in my Canon HV20. Many of them won't play in my Canon ZR400, either. Of the ones that do play, a couple are fine, some have heavy gray horizontal bars, some have some dropped frames and glitches.

    Since clearly there is a difference between my two Canon units, I'm wondering whether anyone out there has knowledge of a camcorder or deck that is known to be particularly sensitive and likely to be able to read these partially degaussed tapes better than my ZR400. Or knows whether my Canon or another brand can be opened up and have its playback gain tweaked.

    If the family identifies any tapes which must be recovered at any cost, I'll send those into a company that specializes in it, but wondering if there's a player known to have excellent playback sensitivity.

    Thanks,
    Chris
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  2. aBigMeanie aedipuss's Avatar
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    doubtful it was the drive. the tiny(but powerful) magnet in there loses it's magnetic force at the cube of the distance from it. it's not detectable on the outside of the bottom of a hard drive and barely there on the top of a hard drive. any more than a quarter of an inch away from the top cover and there is no magnetic field.
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  3. Member
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    Thank you for the reply.

    Whatever caused it, more than half the tapes either appear blank or have drop outs or horizontal bars, and it just happened. I dubbed the tapes just a couple days earlier and noticed the problem when I went back to check the dates on a couple tapes.

    Still wondering if there's a camcorder with better playback of marginal tapes than my Canon ZR.
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  4. Member Cornucopia's Avatar
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    just to clarify what aedipuss was talking about:

    Hard drive platters contain lots and lots of magnetic regions, but MOST of the time these regions are RANDOMLY magnetized (in the aggregate), so the end result cancels itself out and the remaining "polarity bias" is not strong enough to affect regions more than millimeters outside of the drive.

    However, fridges are often built with door panels that are meant to be magnetic.
    Have you ever taken a non-magnetized paperclip and magnetized it? It was magnetic before, but the overall effect was negligable because internal regions of magnetism cancelled each other out. But you put it against a reasonably strong magnetic field and the paperclip's magnetic regions "fall in line" with the prevailing polarity of the field. NOW it's magnetized!
    Same thing happened with your harddrive on the fridge. BEFORE it was on the fridge, it wasn't really magnetized (to any degree that would affect other items), but once you put it near/on the fridge, BOOM! It's a strong magnet.
    So what happened with the harddrive you put by the tapes? Hard to say, as that depends on what happened with the harddrive prior to putting it down there...
    Of course, there could be other reasons - putting tapes on top of speakers is a common mis-occurrence (those are ALWAYS STRONGLY MAGNETIZED).

    Regardless, yes, you should try out a variety of DV-tape playback devices. However, most of them are calibrated to expect certain ranges of levels of magnetic strength. If those tapes have had their magnetic domains modified to where there is a dc bias, or if the strength is below/beyond that range threshold, there is NOTHING you can do with standard decks. Then, the only recourse you have is to take them to a professional "restoration" house (often ones that deal with forensic material) that has pro decks (and a qualified engineer) that they can temporarily modify that "range" so it hopefully is sensitive to the remaining magnetic makeup on those tapes.

    But don't get your hopes up. Even if it works (which is a long shot), it could cost $$$.

    Scott
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  5. aBigMeanie aedipuss's Avatar
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    i wasn't referring to the platters but the extremely powerful rare earth magnets that are used to move the read/write arm assembly from track to track. but even with their strength they don't effect the data on the platters, nor anything outside the drive.

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  6. aBigMeanie aedipuss's Avatar
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    as for a better read on the tapes, you said you just dubbed them? are the originals or the copies bad? first thing i would do is get a new head cleaning tape and use it in both cams. then use it again before trying to read a different brand tape.
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