used the card without problem for two weeks, but the IC3 usb chip seems to have died
after having had one day of problematic connections with the pc. the power led is on, but no
USB connection.
tested on different pcs, differents OSs.
tested every other component of the USB side of the board, however, i don’t know how to test this one.
please assist. 
If you have a multimeter then you may check the USB connection by measuring the voltages on pins 15 and 16 of IC3 (to the GND of the USB section of the board).