Franc Zabkar wrote:
On Mon, 25 Oct 2004 23:34:16 GMT, "Mike Kennedy"
put finger to keyboard and composed:
example how it could get out of alignment.. Say the bearings started to
loosen up or say the read head that is glued on to the metal arm loosens up
and moves very slightly.. A hdd is a very precision instrument, it doens't
take much to mess one up.
I would think that if a head came adrift then the drive would suffer a
head crash, in which case both the head and the data surface would be
catastrophically damaged.
Although I have no way of ascertaining exactly what the problem was, it
might be noteworthy to say that NOT ALL the data on the drive was
recoverable with the freezing technique. Some areas of the disk were
able to be read when the drive was cold, but others were not. One would
think that if the heads were out of alignment or there was some other
mechanical problem, that ALL the locations would be equally effected.
During the recovery attempt it appeared that some locations were more
easily read than others, and that once the temperature rose, even they
were more difficult to read. That being said, it appeared that those
areas were marginal and that the colder temperature pushed them slightly
over a threshold.
Please do not construe my comments as having arrived at an explanation
to my question. I have no proof one way or the other, and all comments
or theories are welcome. This might remain one of life's great mysteries???
"Franc Zabkar" wrote in message
. ..
On Sat, 23 Oct 2004 16:50:56 GMT, "Mike Kennedy"
put finger to keyboard and composed:
It could be a mechanical problem. Have you ever taken apart a hdd? The
read
head is very small and very sensitive. The drive has to compensate for
heating and cooling off in normal operation. If it didnt, it wouldnt work
once the drive started to heat up. I think it may have gotten a out of
alginment from getting too hot and freezing it was just enough to get it
back inside specs.
Modern HDDs use an embedded servo, so I can't understand how alignment
could be an issue.
- Mike
"Ken" wrote in message
...
LASERandDVDfan wrote:
1. Semiconductor junctions have a leakage current that is temperature
dependent.
2. Solder joints that are intermittent can be thermally sensitive.
3. A hairline crack in a circuit board can be thermally sensitive.
Others will no doubt add more.
I don't think there is anything more to add.
As you said in a fantastically detailed fashion, it is likely a
problem
in the
drive electronics which has made one or more critical components
thermal
sensitive.
What is important now is determining how the drive sustained such
damage
to
allow this condition in the first place.
For instance, if it was the result of an overheating problem in the
computer
itself, this would be an issue that requires effective ventilation to
prevent
it from occuring again. - Reinhart
Thanks to all who replied. One thing I did NOT mention in my original
post was that I had acquired an identical HD with the same firmware so
that if the logic board was the cause of failure, I could get the data
off the disk. Swapping out the logic board did not improve the
situation. My reason for suspecting the logic board was that the HD
appeared not to get up to speed fast enough. Upon powering up the HD,
the computer bios would NOT initially detect it. If I did a warm
reboot
while still powered up, it would detect the drive as being present on
the second attempt. This logic board swap DID NOT improve the ability
to read the drive, but I thought the motor drive might not be getting
the disk up to the proper RPM's fast enough. When this did not solve
my
problem, I went into desperation mode and froze the drive.
Myself, I tend to agree that some connection or the IC inside the disk
was being effected by the cold enough to allow an otherwise weak signal
to be read. It is hard to understand how a mechanical function could
be
effected by the cold that would give the same results. However, I am
always willing to learn new things.
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