Tbird, you'll need a multimeter or continuity tester to tell which wire is which. You can make a makeshift tester using a light bulb and a battery. attach a wire to the negative end of the battery. Then attach another wire to the positive end of the battery and one of the contacts on the light bulb. Attach a 3rd wire to the other contact on the light bulb. Now strip the two remaining loose ends of the 1st and 3rd wire. Also strip the ends of the connector. Then insert one of the loose wires inside the center of the connector. Finally touch the remaining loose wire to the stripped ends of the connector. Only one will light the bulb and that one is the positive. I don't know if I would attach the camera to the psu, but if you do, attach the negative side to the black wire, the chassis may work, but the wire is a better choice.