Apple cinema display 23", first some times do not open, solution open power supply and i find one "balloon" capacitor, after that change, work perfect again, now, make black screen with sound, and after few seconds open again, i check power suply with multimeter, and I see is not support 24 volt. i try to insulating the middle arc from power usb, and work again, I suppose its power supply is foul, and not the monitor