Since the upper and lower rails are shorted I´ve figured that if I disconnect the bottom (+15v) rail from the three brown cables and then take the cards out one by one I could identify which one causes the short easily. The short has stopped only when I take all of them (naturally). But if I bring a single one back it causes a small short (0,1ohm or 098 on diode continuity check with a short beep). So it´s supposed to be like that or are all of them bad?
Thanks in advance for any help