Hi
as I have one (but want to sell it with my MP3 hub) I'm not able to open it just to find out. As your receive (it's a RS232 connection with only three wires needed: TX + RX+ ground) works just one pin is wrong. In case you mean the USB connection it's the same: RX seems to work but TX is wrong; Black is mostly ground, red is V+.
Hope this helps a little
Sam