I've got a Yamaha humbucker from a late 80's or early 90's Yamaha RGZ. I cannot find online anywhere or figure out the correct wiring for it. It has four wires (white, green, yellow, red) and a bare wire. Anyone know what the wiring schemes are for this? I checked the Yamaha manual site and they don't go back this far and the newer pickups have different color wires.