CNC controller board and strange laser power modulation

Posting this for a friend, hope someone can be of help!

the Basic problem

I am cutting a SQUARE from a piece of ply with a high powered dual diode laser module & its dedicated controller.

My laser puts out about 30% LESS power when moving front-to-rear in the Y axis direction

Y drives 2 motors… so logically I thought was that the laser is being starved of power…

Nope… wrong again…

Part way thru the Y movement I pulled a Y motor connection & the laser instantly puts out the same/proper power as when moving in the X direction - left to right…

so, I fitted a 10 amp 12 volt power supply for the motherboard & laser, and hooked up an external stepper amplifier solely to drive the two Y motors - with its own 12volt 10amp power supply.

This external stepper amplifier is capable of driving BIG Nema23 motors or bigger, and has no problem driving a pair of Nema17 motors.

The same issue occurs, that the laser is weaker in Y direction…

So again I pull a single Y motor connector & the laser instantly pushed more power & makes the cut.

The motherboard & laser have one 10 amp power supply


the Y motors have ANOTHER 10 amp power supply via the stepper amplifier,

yet the laser still drops power in Y direction unless one Y motor is unplugged mid run…at which point the laser resumes a clean cut again.

The two powers supply units work, and the only electrical connection between the stepper amplifier and the motherboard are the signal feeds to control the external Y motors amplifier.

I have swapped out the Y motors for smaller lower powered units, swapped out the motor cables, swapped out the mother board & multiple nano-boards.

It seams like there is some electrical interference (RF or Capacitance) that is feeding back from the dual Y motors that is interfering with the laser signal…


I fitted ferrite rings to the motor cables - to all 3 motors, and to the power supplies, and the laser signal cable from the Motherboard to the Laser control module…

and still the laser reduces power in the Y direction.

Has any one got any ideas on this & what could solve the problem.

Did I understand correct that you have connected both Y motors to one stepper driver?
If so, are they in series or parallel?

I would hook up one power supply for the laser, and the other one for the motherboard & motors. And don’t forget to connect GND of both power supplys.

Hi Claudio, the control board is an Eleksmaker 2 axis board so the two Y axis steppers run through one driver. I’ll pass your reccommendations on, thanks.