Dreamcast mainboard repair

[aykiri1]

Hi

i saw usually audio and video problems from mainboard. but now i have several mainboards from another problem

seems short circuit i am not sure (when power on power supply have noise)
i checked much components. no one damaged

any suggestion ?
thanks

[Gillbert]

Check PSU voltages (3,3v, 5v and 12v).
Also, you may check if there is a short circuit in one of these vcc rails on motherboard.

There are very few situations where a PSU refuse to work properly because there is no load on 12v rail (e.g: without a GD-ROM inserted).