SATA HD from laptop

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I recently performed a data recovery by taking a SATA drive out of a  
Mackbook and connecting it internally to my PC.
(I use Linux and it can read HFS+)

All worked fine.

However, before I opened the case to my machine, I figured it easier to  
just put the drive into a (known working) SATA external drive case.

When I put the drive in the case all the drive did was "clunk"  
continuously and my machine did not recognized it.
I use this case quite often to do data recoveries and have never had a  
problem...however this was the first time I used a laptop HD.

Anyone know what was going on?

Re: SATA HD from laptop

philo  wrote:
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The only thing that comes to mind, is a voltage problem.

Some enclosures now, they come with an external +12V adapter,
and they cheap out by using a 7805 linear regulator inside the
enclosure, which further converts +12V to +5V for the controller
board. The 3.5" drive needs both rails,  but one rail comes from
outside, the other rail comes from inside the enclosure.

If you put a 2.5" SATA in the housing, those don't draw any +12V,
and all the load is on +5V. The spinup current value is 5V @ 1A
for the first ten seconds. Then, the current drops to a lower
level. And that level should be below half an amp. The current draw
changes, as the drive does read, write, or idle.

Now, say the 7805 regulator in the enclosure, is under-rated
(like maybe, a 78L05). And it heats up to >100C, and then switches
off on thermal overload. When it cools down a bit, it re-applies
the +5V rail. The drive could sit in a spin-up-spin-down loop, as
it tortures the 5V regulator.

Older 3.5" enclosures, they used a 4 pin mini-DIN, and the external
power supply was dual rail. The external adapter provided a beefy
+5V and +12V, and you wouldn't have the same potential for a
powering problem.

So I'd be eye-balling the tiny controller board inside the
enclosure, and seeing what size 7805 is present. And what
kind of current flow level it might be able to sustain. Even
a 3.5" drive can draw enough current from +5V to heat up that
regulator, so you'd think by now, you would have seen a problem
with a 3.5" as well.


There is one other remote possibility. If you look at the table in the
section labeled "power connectors", one of the power pins can be
re-defined as a "staggered spin" control signal. I don't know under
what circumstances that function is used, as normally, I'd expect
pin 10,11,12 to all be wired to the same GND (black wire).


Re: SATA HD from laptop

On 03/07/2013 06:38 AM, Paul wrote:
Quoted text here. Click to load it

OK...thanks, that sounds like what it is.

Though that enclosure is now "buttoned up" again I have a few more in my  
work area and one of them has a very low 5 volt supply.

The other one I am just running off of an old "AT" power supply...
no shortage of current there!


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