At 02:45 PM 10/30/2002 -0700, you wrote:
> >         Got a HDD that stopped working.  I'd like to get some data off
> it, but
> > want to try and do it myself (it's that tinkering thing).  It spins up.  I
> > do NOT hear the normal scratchy noise like when the heads crash.
>
>Well, thats a promising start.
>
> >         Tried putting it in the fridge for 30 min. and then running it
> (had a
> > couple people say this might work).  No luck.
> >         Tried tapping it on all sides.  No luck.
>
>Tapping is for when the heads stick to the drive platter.
>
> >         So, I bought another drive exactly like it.  First I tried
> swapping the
>                                      ^^^^^^^^^^^^^^^
>INCLUDING the revision level of the electronics??
>
> > electronic board from the good HDD to the bad HDD.  No luck.
>
>A good start but the HD preamps or servo amp may have been toast. A write
>amp failure would wipe out the servo sectors and render the platter
>unreadable.
>
> >         So, I started to get desperate.  I too apart the drives and
> took the head
> > units out and swapped them.  No luck.  At this point I have swapped
>
>You'd have to get the 'home' position -exactly- correct for the drive
>to initialize properly. Did it try to move the heads across the platter?
>Did it bang them at one end, several times trying to find home track?
>
> > EVERYTHING from the good drive to the bad drive except the platters and
> > motor that makes them spin and still have had no luck.  The PC just doesn't
>
>Did they bad platters spin at the correct rate? If one field (or FET) of the
>drive motor was out, it shouldn't spin, but if it did, it would
>be slow and so the data would not decode properly.
>
> > see the HDD there at all.  I can put a good HDD in there and it works fine
>
>Even with the NEW electronics? Generally a drive will respond to
>a 'drive identify' command even if there are problems with the media.
>What make/model of drive are you trying to resurrect?
>
> > (so it's not the PC itself).
>
>A reasonable presumption, assuming that when you moved the heads over,
>you also moved the matching electronics. Even then, they have
>changed the way they write the tracks and so the firmware
>won't recognize the old platter format (hence the importance of matching
>the revision levels).
>
> >         I moved everything back to the good HDD and it still works.  I
> know the
>
>Wow. You can fix my dead drives anytime. I did the same as you, but the
>Seagate guts simply refused to recognize the platters after the move back.
>(the 1.6GB drive were notorious for failure).
>
> > whole deal about "clean room environment", but hey it still works for now.
>
>As long as you keep the big sticky stuff off the media, you can do ok
>with a final blast of canned air to clean it off.
>
> >         Anyway, does anyone have a clue what to try?  Since I swapped
> everything,
> > I can't figure out what's wrong.  Is there something you have to do to make
> > the new head unit recognize a new set of platters?
>
>I think your problem may be a difference in the media formatting between
>the old and the new. Did you try using the New heads with the OLD
>electronics in case it was a preamp problem (Connor drives were bad
>for servo amp failure).
>
>Do you have a scope that you could use to compare the head signals
>between the two drives? If a head controller failed, it could wipe
>out the servo sectors with the results that you describe above (new
>everything but still no joy). It could also be that you didn't quite
>get the home position correct so try again with new heads/old electronics
>IF you see that sll heads product correct looking signals. You'll need
>at least a 50Mhz BW scope to see the RF envelopes correctly.
>
>Robert
>
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