Q:
Recently, my HP laptop USB interface got a failure, that is, it could not recognize any external device, what am I supposed to do to fix up the USB interface failure? Hope to get your any suggestion and help, thank you a lot!
A:
1. USB interface cannot work, usual reasons are as below:
1) System problem, it will be fine if reinstall operation system.
2) USB interface is aged and broken, after changing the USB interface, then it’s OK;
3) The soldering on South Bridge BGA encapsulating main control chip is broken, which needs to send to repair, it would be OK by professional soldering device to weld or change a South Bridge chip.
USB interface has four cables,
a) 5V power cable;
b) Ground cable;
c) Data cable +;
d) Data cable -;
If your USB mouse light is still on normally, then it means there’s nothing wrong with power supply. The power supply is controlled by a switch chip, if the USB mouse light is out, then it’s quite likely that the switch and the protection resistance connecting with it are broken; besides, 2 data cables are directly connected to the South Bridge through two little inductances, if there’s something wrong, probably the little inductance goes bad or breaks down, or the USB control part of the South Bridge gets something wrong. For USB part, most cases, as pull and plug USB devices, static strikes through the South Bridge. You can test the USB data cable’s ground resistance with a multimeter. If the resistance is extremely slow, then it means the