Post originale di: Mario T ,
Make sure you're using the original PS1 controllers. Later controllers for the PS2 (and obviously, for the PS3) have other features that the PS1 may not recognize. (Been a LONG time since I pulled out my PS1 so I may be wrong about that.) Failing that, I would start by cleaning out the controller connections in the PS1 itself with some q-tips and rubbing alcohol. As a last resort, you can start taking the box apart and inspecting connections for corrosion and loose connections.