[sawdust]

could be a solder bridge around the chip legs you soldered to get a good strong Magnifying glass and look over these points at diffrent angles does the ps2 boot a Original ps2 game when the chip is disabled if it will you could have a dry joint(wire not in good contact with solder)or you could have a brake in the wire, get a set of test clocks and ground one of the wires from the clocks on the ps2 mobo ie copper bit at the side of the board make sure that it is clean so you get a good contact, now other side test all the solder points on the duo chip set the clocks to 2000 omes and you should get a reading off all points if your wiring is ok. Will the ps2 boot ps1 backups if it will then the wiring is the fault if not you could have a dead chip duos are very good chips and a dead chip is rare but can happen