On Jul 30, at 5:21 AM, Stuart Ungar wrote:
I've been having issues with a USB 2.0 powered hub. Some things plugged into it seem to work on and off. Is there a reason for this? Items plugged directly into the back of my mini work fine, but i only have 2 USB ports back there. Could the hub be bad? It is driving me a bit crazy.
I had a Belkin 4-port hub that was similarly driving me crazy because a cheaper 4-port Ananté worked fine with the same devices. I finally figured out why. The Belkin had a wall wart that gave 750 mA output and the Asanté's was rated at 1.2 A (1200 mA). The USB specification says that a single device can draw up to 500 mA through the USB port. With some combinations of four devices plugged in, the power draw sometimes exceeded 750 mA but not 1200 mA.
Notice that neither device could handle a 500 mA device in all four ports.
I've got a Dell 7-port USB hub in my office that came with a 1A power supply. I've never tried it with more than three devices.
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