Hello.

I recently got a used k40 (best I can tell it's from 2017, analog setup, white and blue) It came with a Cohesion3D Mini LaserBoard.

I have the Cohesion3D board powered by a separate 24v power supply. I've watched countless hours of videos and read all I could find on the forums about it to make sure I've hooked up everything correctly.

I run LightBurn 1.2.01 and everything works except that when I press "start" on a job the head moves and (interestingly) the Amp meter needle moves, but there's almost NO POWER (low to no intensity) coming out of the laser no matter what power settings I use in LightBurn.

I have the machine's potentiometer set to 11 Amps.

When I press the fire test button everything works great, the beam is focused and centered, aligned. (That makes me think the LPSU and laser tube are ok.)

I've tried doing PWM calibration and everything works with the standard setting of 200 microseconds period. The tube fires exactly like it's supposed to.

I've gone over the "config" file and confirmed that I have the right settings according to a bunch of other people on the forums. I've tried multiple different versions of the firmware (old and new) and this issue persists.

Seems like the S-Value is the culprit.

I have the digital LCD that comes with Cohesion3D and there I can see that the S value is set to 0 after every code command from LightBurn.

I tried running manual commands in the Console in LightBurn and when I do that and specify the S value of my choosing everything is good.

I run a Win10 laptop and have installed the regular (Gcode only version) of LightBurn.

This makes me think that the problem is something to do with the way LightBurn formulates the Gcode commands before sending them to the Cohesion3D board.

Any ideas are greatly appreciated!

I'm out of ideas and really hope someone would be able to help.

TLDR: k40 C3D mini laser fires fine except when LightBurn sends Gcode commands S goes to zero. WTF lol