Old pioneer cd changer of 12 cd's.?

my friend got this old pioneer cd changer of 12 cd's, but he instqalled wrong on his boat, so it kind of burned i guess, he told me that some dude electrican or somethin can fix it, but he needs to know what's the voltage of it, cause he dosen't have the manual, like i said is really old. if anybody knows something please contact me.