Open up the machine, look inside near the battery area, there should be a label stating the needed DC voltage of the game. Usually, its 6v. You will need a power adapter transformer, such as Radio Shack universal AC adapter 273-1650. This transformer can adjust power from 3v-9v if needed. Newer machines might need a larger transformer that can produce more amps. This will get you started. When you buy the transformer, have the sales person mark the + and - wires using a meter, should you not have one at home. You might also need to buy wire to connect the transformer to the machine, if the machine is not close to an electrical socket. Add wire if needed, observe polarity. Disconnect the + of the battery and attach + of the transformer to the wiring of the machine, use wirenuts if handy, or electrical tape to seal connections. Now do the same to the - side. (remove battery from machine) Plug in and test. HAVE FUN! :0)