power surge on USB ?? HELP !!

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Guest

i have got an external hard drive which i have previously used on other
laptops and pc's, but i have just come to connect it to my Compaq laptop and
when i plug it in i get a message sayin ' Power surge on USB device' or
something along those lines.

is there any way around this ?? as i have important information on the hard
drive which needs putting on my laptop.

cheers, tom.
 
Has it ever worked on this particular laptop? If not, then perhaps the
power supply is not quite enough to handle the external drive. Could
you temporarily network your laptop with another computer (with the
external drive connected to it) and set up a shared folder (using My
Network Places) to transfer the data to your laptop?

GP

--->
 
GRAND_POOBAH said:
Has it ever worked on this particular laptop? If not, then perhaps
the power supply is not quite enough to handle the external drive.
Click to expand...


External USB drives have their own power supply.
 
Not all of them do Ken. I have one right here whose marketing
catch-phrase was "powered by your USB port". It is a micro 40Gb drive
and fits in my pocket. Not RAM, it actually IS a drive. My brother sent
it to me from Japan.

GP

--->
 
GRAND_POOBAH said:
Not all of them do Ken. I have one right here whose marketing
catch-phrase was "powered by your USB port". It is a micro 40Gb drive
and fits in my pocket. Not RAM, it actually IS a drive. My brother
sent it to me from Japan.
Click to expand...



OK, then I stand corrected. Nevertheless, the *great* majority of the time
what I said is correct, and the laptop's power supply isn't an issue.

--
Ken Blake - Microsoft MVP Windows: Shell/User
Please reply to the newsgroup

 
Not all of them do Ken. I have one right here whose marketing
catch-phrase was "powered by your USB port". It is a micro 40Gb drive
and fits in my pocket. Not RAM, it actually IS a drive. My brother sent
it to me from Japan.
Click to expand...

How much current does device draw? Remember numbers from the USB
standard. Device must not draw more than 500 mA. If excessive, then
USB port must remove power with an error message. Fine. What
measures that current? First, that current measurement circuit is
unique to hardware. That port may have as much as 10% error.
Therefore a USB device drawing 480 mA might be detected as too much
current by some ports.

Second, also part of that design is how long overcurrent is
permitted. Is that response also determined by software or hardware?
Some have reported USB ports working just fine until Microsoft updates
were installled.

In short, when a USB device draws anywhere near to 500 mA (which is
only 2.5 watts), then some USB ports may report "power surge". A
problem create either by point one or point two; or both.

Typical disk drives draws maybe 10 watts. A special low power
version would certainly be at the max limit - 2.5 watts.

Two ways around this problem. One, the drive has its own power
source. Or two, a self powered hub may have better current
measurement accuracy and therefore not report excessive current.
 
i have got an external hard drive which i have previously used on other
laptops and pc's, but i have just come to connect it to my Compaq laptop and
when i plug it in i get a message sayin ' Power surge on USB device' or
something along those lines.

is there any way around this ?? as i have important information on the hard
drive which needs putting on my laptop.

cheers, tom.
Click to expand...

I use an external hard drive too.It is a Seagate 100gb "portable"
external USB drive. It also has TWO leads with it. One lead is a data
cable and the other is for USB power.

When sing ONE data lead the USB port indicates a power surge. When
using TWO leads that come with the drive...I receive no errors.
However I do use a POWERED USB hub now.. The powered USB hub solved
the problem when using ONE lead and provided the addistional USB ports
that I needed for additional attacments to the PC..
 
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