The harddrive wont power up witout the power cable attached to an extra usb port but now I keep getting a message saying USB device not recognised and when i go to the device manager it says unknown usb device. Any advice please

Try a self-powered USB hub. They're under $20 usually, don't drag down your power supply and give you extra ports to use.

Also open Device Manager, Universal Serial Bus Controllers, each USB Root Hub, and under the Properties, Power Management tab of each one, disable the option to "Allow the computer to turn off this device to save power".

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not a bios problem but a usb port driver problem

INSUFFICIENT POWER - USB PORT
If you get an error message "Insufficient power to operate USB device" when you plug a USB device into the computer's USB port or the un-powered USB hub that is attached to the computer's USB port, then this device is drawing excessive current that the USB port cannot supply. The maximum output from an USB port is 500mA. In case such as this, you need to purchased a powered USB hub and connect this hub into the computer's USB port and then connect the USB device into this powered USB hub.

The power adapter could be faulty.
If you get an error message"Insufficient power to operate USB device" when you plug a USB deviceinto the computer's USB port, then this device is drawing excessive currentthat the USB port cannot supply. In case such as this, youneed to purchased a powered USB hub and connect this hub into the computer'sUSB port and then connect the USB device into this powered USB hub.

Hi,
- Make sure you have been installed JVC driver on your PC - If your PC has multi ports USB, just try other ports to make connection - check your firewire, it may be malfunctioned . Try other USB cables

This is not a big problem if the tablet works. There are three simple possible solutions to this problem:

1) Sometimes you can plug USB devices into a wall socket so you don't rely entirely on the USB power. See if the tablet can be attached to another power source - if so use the appropriate power adaptor to plug it into a wall socket.

2) Very few USB cables are designed to carry much current. This design keeps the USB cables thin and flexible. Try purchasing a USB cable that looks like it can carry the extra current. Unfortunately USB cable manufacturers do not display how much electrical current their cables can deliver efficiently, so you will need to guess. Generally the thicker cables can carry more current - these cables are *not* necessarily the expensive gold-plated ones. You can usually find a thick cheap one that will do the trick - but it will take a little experimentation. Try different thick USB cables to see if one makes the problem go away.

3) get a special USB cable that takes the power from 2 USB ports and delivers it to one device. These are strange looking USB cables that have an extra male adaptor cord hanging from a USB cable - the cable has 2 male adaptors and 1 female adaptor. Of course this will take up two USB slots on your USB hub.

Hope these help!

this is the fault of your usb port, its a hardware problem, its better not to use that port, use a usb hub if you want more usb ports

I think you are using an 2.5" notebook hard disk drive into this external case which hasn't got an extra power supply.

Since you're using an USB1.1 connection this could be a USB1.1 issue, USB2 returns more power to the connected device, since you connected you harddrive too an USB1.1 port you might need an USB cable which you can plug into 2 USB ports.

By doing this one USB port will provide the power to spin the drive up (which needs a lot of power) and the other cable will be able to focus on the data transfer.

You can also check your disk manager, it could be the drive is requesting a drive letter that's aready in use by another device. Go to start -> right mouse click on My Computer -> manage -> storage -> disk management. If the device is within this list you might attach another drive letter to it by doing the following. Right mouse click on the disk -> Change drive letter and paths and there you change the current drive letter into another one.

Try different USB ports on the computer to see if its a porblem with the port connection and if there's no change there then try using another USB cable that you know is working perfectly fine.

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