We have a laser with an RDC6445G controller and a 4-Wheel r
Basic truth: ignore the color codes!
The Y axis motor wires (R G Bk Bl) terminate at the stepper motor controller inside the cabinet. Look at the side of the driver to see the motor winding connections:
Write down the wire colors at the A+ A- B+ B- terminals.
Unplug the rotary motor so you’re looking at the bare wires.
Get a multimeter, set it to measure continuity, and measure pairs of wires until you find two pairs. The two wires in each pair will have continuity (= low resistance) to each other and no continuity (= open circuit) to the other two wires. I’d expect the pairs to be Bk Bl and Bk Bn, but measure to be sure.
Then connect one pair to the driver wire pins for A+ A- and the other pair to the B+ B- pins.
With 0.50 probability, the motor will turn backwards from what you expect. If so, swap the A+ and A- wires.
Then it should Just Work™.
I make a jumper cable, without jumper for one machine, use the jumper on the other. The wiring change occurs in the short jumper cable. That way you don’t break it for the other machine.
Thank you! I will try 
BTW - there are only 3 wires from rotary step motor.
Whoops!
In that case, you cannot use that motor with the (presumably) standard two-phase bipolar stepper motor driver in the machine, because it is not a two-phase stepper motor.
Most likely, it’s a three-phase motor and, thus, requires a three-phase driver. You’ll find all three wires have a similar resistance to each other, because the windings are connected in a Y configuration inside the motor.
There is a faint chance it’s an old-school unipolar stepping motor, but that’s unlikely at this late date. If so, two of the wires will have equal resistances to the third and twice that resistance to each other.
The photo suggests the motor does not have a data plate, in which case you’re pretty much out of luck for the specs.
The stepper driver will have its data plate on the side and, if the wiring diagram is similar to the DM542S driver above, then connecting a three-wire motor to a two-phase driver will not work and will probably damage the driver.
All this depends on what type of stepper driver the machine has, so reading that data plate will provide a way forward.
Step motor is 57bhp56-350y
Mayby this could be related 3 Wire / 3 Phase Stepper in my Rotary Needs to be Reversed
If this is approximately the correct datasheet:
Then it is, indeed a three-phase stepper.
Casual searching suggests that the BHP specifies the winding type, as BYGH motors have two-phase windings.
Which means the stepper motor driver inside the machine must be a three-phase driver.
What does the data plate on the side of the driver say?
So it is, indeed, a three-phase controller:
If I’m reading the switches correctly:
Now, trace the three wires from the UVW terminals to the socket for the Y axis motor and those are the three wires for the rotary motor.
With 0.500 probability, the motor will rotate backwards. Swap any two leads and it’ll rotate the other way.
