I need to supply a minimum of 0.5 amps to each port of a number of 10 port USB 2.0 hubs. I have succeeded using 8 amp wall warts so I'm reasonable sure the hubs are capable. I'm powering 8 hubs so that's more wall warts than I want to deal with. I modified a PC PSU, adding a load resistor (10 ohn 10 watt), power led and on/off switch following the many on-line guides.
I have 6 cables off the 5 volt bar, everything is solder and shrink wrap, psu starts as it should. It does supply power to the USB hubs but only a limited amount. I estimate it's about 2.5-3 amps, as all ten of the devices do not work correctly. The measured voltage at each line is 5.01 volts.
I have modified 2 PSU's, one rated at 400 watts with 28 amps for the 3.3 and 5 volt rail combined. The second PSU is rated at 40 amps for the 3.3/5volt rail combined.
I think the problem is because these are "regulated" power supplies, but I'm a noob and I'm totally lost at understanding why I'm not getting even close to the rated current of the PSU's. I would appreciate any advise or constructive criticism.