Tom wrote:
> Hi All !
> I need to get the data off an Acer Laptop's HDD as the Acer's keyboard
> refuses to function - I suspect a controller chip on the mainboard has
> blown.
> Anyway I have the laptop's HDD out of it and I have a USB to IDE
> convertor that has both 3.5 and laptop 2.5 inch connectors - but what
> do I do about the power supply? For 3.5" HDDs I use a power cable from
> the PC.... but for the laptop HHD there is no connection for the
> power.
> Any help gratefully received. Many thanks.
> Tom
If you look at the connectors, the 3.5" drive has 40 pins and they're
all data pins. The 2.5" drive has 44 pins, and some of the extra 4 pins
are involved with power. If you look at the adapter, there should be
room for a power connector on the adapter. There has to be some
mechanism, by which +5V can flow through the adapter dongle, into
the 44 pin 2.5" drive connector. So look carefully at the kit you
bought, for a power adapter cable.
A 2.5" drive runs from 5V. Current flow is about 500mA.
A 3.5" drive uses 5V and 12V. Around 12V @ 0.6A and 5V @ 1A. Needs power adapter.
It could be, that the kit designers chose to power the 2.5" drive,
using +5V from the USB bus power. So there is already a 5V source
there, and that could be how they expected to get +5V to the drive.
If the drive is power hungry, it might slightly exceed the
500mA power limit on USB. In which case, a 5V wall wart and barrel
power connector, may be the solution. Look on the adapter dongle
for a barrel power input, or look for some kind of adapter
cable which can provide more power.
So power does flow through the 44 pin, and it is up to you to figure
out how the power gets there.
If the drive is using USB bus power, you should not run the kit off
a bus powered hub. The kit should be plugged directly into
the computer USB plug. Even if that is done, the computer can cut
off the 500mA of current, if it detects an overload. If a laptop
is being used to provide the host for the kit, then a laptop
tends to "police" current flow more closely than a desktop computer,
and may cur off power precisely at 500mA. Some desktops will allow
closer to 1 ampere to flow, before the Polyfuse opens.
HTH,
Paul
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