Right, wired up with parts from a donated old NEC Mouse.
I have ground where I should have ground and I have 5v where I should have 5 volt.
Measuring between X1,X2 and ground leaves me with 5V which seems to be the same as the existing trackball I have hooked up to the OptiPac but I get no life from it at all.
Tried changing the encoder wheel but still nothing.
Any ideas? Or did I get lucky with the optics showing the right voltage, but unlucky in that they are just not compatible?