Quote Originally Posted by irving2008 View Post
you have 4 windings A1 (red) A2 (yellow) B1 (green) B2 (black). When the motor is used as a unipolar the windings are energised in sequence A1 B1 A2 B2, but in bipolar configuration they are energised in pairs A1+A2, B1+B2. The tricky bit is that the windings are wound as opposing pairs so when used in bipolar parallel arrangement you have to reverse one winding of each pair to align the magnetic fields, hence the pairing of Red with Yellow/White etc.

I'm going to print this out and read it beside the wiring schematic, appreciate your reply.