If you are talking about the power connector on the A590 board, it should be clearly silk-screaned on the PCB next to the connector. If not then the yellow wire goes onto the pin nearest the top edge of the PCB. The black wire goes onto the pin below that and the red wire connects to the 4th pin.
Top edge of PCB
_____________________
o - Yellow
o - Black
o - N/C
o - Red / Orange
Hope this helps you. :-)
