USB is one of the most common ways of connecting peripherals to computers. USB extension cables can increase the distance between a computer and a peripheral. In cases where the USB extension cable isn't working, looking at a few factors should help isolate the problem.
There are two types of USB extender cables. The most common extender cable is a passive cable. Passive cables do not require a power adaptor and don't have a repeater to boost the USB signal. The maximum length of a passive USB cable or series of cables chained together is 16 feet. Cables with repeaters can be as long as 80 feet. When troubleshooting a USB extension cable, the first thing to look at is the length. If the total length of your passive USB extension cable is over 16 feet, the signal may be degrading too much and causing your problems.
To see if a USB extension cable is defective, try plugging the device directly in to the computer. If the computer recognises the device, it could be that the cable is too long. If the cable is under 16 feet and the computer recognises the device when connected directly, but fails to recognise the device when an extension cable is used, it is likely that your extension cable is bad. Try using a different extension cable. If the device works with the new extension cable, the original cable probably has a fault.
Hub Power Issues
There are two types of USB hubs: powered hubs and unpowered hubs. The most common type of hub is unpowered. With an unpowered hub, devices that draw power from the USB hub share a single power source, and sometimes may exceed the amount of power available from a single PC USB connection. Try unplugging all devices, except the device connected via the extension cable. If unplugging the other devices solves the problem, you have likely exceeded the maximum power that the hub is able to supply. If this is the problem, you can either remove some devices from the hub, or replace it with a hub that has its own power supply. Be aware that in a passive hub, you must add the length of the cable connecting the hub to the computer to the length of the USB extension cable and the length of the device cable to establish the total length of the USB extension. Extensions must be less than 16 feet for passive USB connetions.