When the new head comes it will have the voltage hand written on a Small sticker on the top of the head, the disc that comes with it wont set the voltage, the voltage is set on the main board, for example 24.6 volts, to check the voltage you need a multimeter and then dial the voltage to match the head, there is a small wiring harness available from roland that plugs in to a socket near the voltage adjustment screw, then connects to the multimeter. the set up is very easy to do along with the head alignment.