Power supply board has gone "POP".
Find an scrap unit for your region (Are you in U.K. ?) and take the power supply board and power connector to your U.S.A. PS2. That should make it work again.
The power supply board will reduce the mains from 220v AC to 12V DC which is what the PS2 needs.
Resulting machine will work fine connected straight to mains without the step down transformer.
But definitely what has gone POP is the power supply, not the PS2 mainboard.
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...)