SEGA Master System II

Replacement
Virtually any 7805 (TO-220) will do the trick

What is the device power input?

 * +9V DC ± 10%, 0.5A.
 * 5.5mm x 2.1mm barrel plug.
 * Center-pin_negative.png Center-pin negative polarity (tip: +9V DC, sleeve: -9V DC).

Where I can find on the board?
The ground plane is present all around the board as a large copper via (see picture).