My USB connection has broken, but in my case one of the 4 metal contacts when I was trying to get it in to place broked up. So I was having only 3 of 4 metal contacts. I brought my S4 from a guy from my country... so my Kontrol S4 is a second hand gear brought from an national online shopping like ebay. So in this case i had no warrity. I called one guy that changed me the USB B conector from the controller with one new not orange, just white . The big problem it that the S4 is not working now. He replaced the USB connection very carefully, same like original. He also verified every connection of the USB with an measurement device. But it's not working. The new USB B lookes exactly like the original, the orange one. The USB indicator of the S4 is flashing when the controller is conected to the USB port from my mac with the case original USB cable. In the S4 sofware the S4 it's not recognized and looked like NO AUDIO. Please guys help me up. I'm very sad and desperate. What can be the problem? I allready ordered the S4 flightcase to avoid these problems and to protect the S4 and the connection. What sould I do? Sorry for my bad english. I'm from Romania.