Compaq presario c300 usb problem

Well instead of repairing it have you tried an external usb pcmcia card? They are cheep and mine is usb2 4 port on a pcmcia and works fine. Just a sugestion for you. It runs about $14.00. I ave a 900 Compaq and the first to go was the dvd/cd [ replaced ] then the battery [ running off a cordless drill battery now ] and then the usb. I know your question was about fixing this but an easier way is described above. Over current on the usb port is no problem with the pcmcia 4 port usb card as if you need more current, it comes with an external power supply only if needed. I have never had to use this external supply yet. It supplies [ the card ] up to 800ma.
Hope this helped a little...
Kevin