Voltage required

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I have an external hard drive, taken from an older computer, in a Dick
Smith external enclosure. During a move I got all the transformers mixed
  up and now I do not know whether this requires 12 volts or 16 volts.
Any ideas?


Re: Voltage required

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Assuming that this is a desktop type 3.5" drive (not a laptop drive
enclosure all of these I have ever seen since about 2005 from 3
different makers,
are supplied with 12v DC @ 2A (regulated) plugpack
with the centre pin of the DC connector being the positive.

Most laptop drives run from either the USB lead or from an external 5v
(its not impossible that they could use a 6v one and a low drop
regulator or similar?)

If you are concerned and want to play it safe, open it up, remove the
hard drive, apply 12v to unit, and measure the voltage on the power
connector to the hard drive. If it measures correct (+12v and +5v)
then its ok. Install the hard drive and measure again, if it falls
dramatically under load, then its likely not the right plugpack.

Before applying voltages from plugpacks that you arent sure belong to
the unit, check with a meter that the polarity is correct - check the
PCB layout to determine which is ground.
Usually these have internal switchmode regulators to generate the 5v
rail from the 12v input.
the +12v usually runs straight to the hard drive connector (may have a
series diode for protection against reverse voltage).

You can  visually check this to confirm.

Finally, if you know which other item is missing a transformer, and
its a 16v device, then thats more of a clue that the HDD is the 12v
device.  Note also that the HDD plugpack will certainly need to be a

Re: Voltage required

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Most external 3.5" drive enclosures take 12V and 5v from a dual voltage supply
if yours has a socket for a single voltage supply itt's probably for
12v.  these things are usually labeled.

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