Wire Identification

Motor Identification.

 One winding is on each stator pole.Unipolar motors may have 5 leads but generally have 6 or 8 wires. In all the motors we have seen, the wires for the 6 & 8 types come out in two bundles of 3 or 4 wires resp. Unipole steppers have two coils per stator pole. In the 8 lead motors the 2 leads from the 2 coils from both stators emerge from the motor. In the 6 lead motors the two coils on each stator pole are joined (opposite sense) together before they emerge from the motor. In the 5 lead  motors each of the two joined wires are themselves joined  before they leave the motor. In the 6 wire version a multimeter (set it to 200ohm resistance range) will show which is the centre lead within each group of 3 leads. 

5 wire version

6 wire version

 Typically the resistance between the centre lead to the other two will be about 40 ohms while the resistance between the outer two leads will be twice that. Call the outer two leads in each of the two bunches of wires A & B, C & D.  The centre lead in each bunch is the power lead & goes into the pad marked +.  Note that it does not matter which way around the A/B, C/D leads go onto the pads. 

 In the 5 wire motor these centre leads  are  connected internally. Note that both + pads on the PCB are connected together.So to power a 5 lead stepper just connect the common centre tap lead from both phases to one of  the + pads. The A/B, C/D leads are connected just as  in the 6 lead motors. 

Taken from:Stepper Motor Identification