The V3 mainboard is a 2 pieces block. Theres a big square board with all the processors and so. There's few fuses on this board. What I don't remember is if the 8V regulator chip is on this board or on the small board which the Power supply circuit (no not the big board which takes the AC power, but the small board that has the coin battery in it)
The small board with the batt has most of the fuses in it. Remove the 2 screws that hold it and look on it's back side. Test all fuses. Replace the one you find to be open and try to find which controller made the fuse blow !
Never use fake controllers. Never use non Sony controllers and memorycards if you don't want that fuse to blow.
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)