Duodaigost fluoroscopic x-ray was giving system error, when checked found that U1 board located at bottom back of Bucky is faulty, its FET type NG48AB, NG49AB, NG51AB, and NG49AF were short. i canot found any alternative of these parts, even i did not found the data sheet of these parts.. can any one help in this regard, same or alternative of the parts.