First of all thank you for your help and sorry for my bad english ....
On my Variax standard the original pickups hot signal wires are not all white but white(neck), yellow(middle) and blue (bridge)...
Anyway, I cutted the original pickup wires as suggested in this video, just to not mess with the PCB and soldered the new pickups on those wires and not directly to the PCB.
so i considered the black wires as the ground and the colored wires as hot signals, but in position 2 it sounded really bad, it was thin and dull so i had to reverse the neck pickup wires to achieve the typical strat sound in position 2.