How to recover a crashed laptop hard disk (windows NTFS)

External Since: Nov 07, 2003 Posts: 1692

In comp.sys.ibm.pc.hardware.storage Zak Hipp <penpoint RemoveThis @ntlworld.com> wrote:
> bluerhinoceros wrote:
>> Erica Eshoo wrote:
>>
>>> Electrical recovery for not spinning drives
>>> - Connect to a high wattage power supply
>>
>> I don't understand this one. Doesn't the device draw the amps it needs
>> regardless of the supply's maximum output rating? I can see it making
>> sense if the original power supply was overloaded/overrated and not
>> really delivering, but the video implies that the power supply "pushes"
>> the current rather than allowing the device to draw it.

> Watts = Amps * Volts (W=IV)

> If a maximum rating of a supply is 100 Watts and the desired
> electron pressure to be maintained is 10 Volts then a maximum of 10
> Amps can be drawn. Therefore if 15 Amps is drawn then the electron
> pressure must fall to 6.667 Volts.

Nice try. This would be for a wattage-regulated output. This is
a voltage regulated one, i.e. there is active circuity that
does maintain the elecron pressure at all cost. It will deliver
constant voltage, until the a second circuit becomes active,
namely the overcurrent protection. Then the voltage will drop
to zero and you typically have to power-cycle it. The way this
works is that the PSY can actually deliver much more power for
a short time (miliseconds), but would destroy itself by overheating.

> If 10 volts is required for
> correct functioning of a circuit drawing 15 Amps then a power supply
> of 150 watts is required (W/I=V).

Indeed.

> I have no idea if this sort of
> thing works but I understand the reasoning. A component may have
> stepped outside the desired specification, say a resistor with a
> lowered value, allowing a higher current to flow and exceeding the
> ability of the power supply to maintain correct voltage levels.

Not how it works except in very rare failure modes, were the PSU has
lost enough of its rated power that it cannot trigger the overcurrent
protection at its rated output voltege anymore. Or if it does not have
overcurrent protection in the first place. A very badly designed
and dangerous (fire hazard) PSU might not have it.

Arno

External Since: Feb 01, 2006 Posts: 1570

Erica Eshoo <evesunflor DeleteThis @sbcglobal.net> wrote
> Gary R. Schmidt wrote

>> Nothing may work, but before the next try, put the disk
>> inside a plastic bag, seal it, and put it in the freezer for
>> an hour or two, then *very* quickly try to recover the data.

> PC World says the freezer trick will only work
> for a clicking but not spinning hard disk drive.

PC World is just plain wrong. There are quite a few examples in
groups.google of it working in other circumstances than just that one.

> My IBM laptop hard disk is clicking AND spinning.

> How do I know it's spinning? Well, when I press on the cover while
> the hard disk is powered up on the external Vantec IDE-to-USB
> adapter, I can hear the spinning hard disk rub against something
> as it grinds to a halt so I'm pretty sure it's spinning.

Fark, thats not a good idea at all. You may
well have metal filings inside the chamber now.

You can see if a drive is spinning by feel alone, no need to press on it like that.

> So, I don't think the freezer trick will work.

See above.

> Still, I've had the hard disk inside the freezer wrapped in a cloth inside a
> zip-lock bag for about 18 hours now. PC World suggested up to 24 hours

Thats for a different problem, stiction, which you clearly arent seeing.

> - so I'll let you know if it worked even though my disk was clicking AND spinning.

> http://www.pcworld.com/video/catid,1610-page,1/video.html
> How to Resurrect a Crashed Hard Drive - PC World Video

Just another superficial steaming turd.