QUOTE(merton123 @ Dec 22 2010, 09:31 PM)
it is a small in car screen i used to run it from a small 12v battery fine so ill check out the advice for now.
i have tried these points but i think ive done something wrong. before i had a small bit of power, now nothing at all. i only have red and black so i dont know what would be the best conneciton for it
you need to ground the power on pin on your xbox psu off course; without sending the 'power-on' signal by your xbox; the psu will not power on (you should only have power on the standby line of the psu; i don't know how much that is on the xbox psu. 3.3 or 5 volt? (5 volt is normal for computers; the old xbox uses 3.3 or 5 volt)).
you have power on your psu if:
xbox 360 sends the power on signal to your xbox; then your psu kicks in to give all the voltage you need / it can supply
ground the ps-on pin of the psu; then the full power will be supplied as soon as you power the psu (put the power cord into the wall outlet).
it might be save to put a fuse between the xbox psu and your lcd; a couple of amps will do. cost around 1 or 2 dollars...(fuse holder included). better save then sorry