Solved Problem with my Relatively New K40 with C3D Laser Board and Garbled GLCD

Hi everyone,

This is my first post. I spent some time searching for this problem and didn’t find an exact match. I did however, find related information in this forum that pointed me in the right direction.

I’m posting this in hopes that it will help someone else solve this problem.

This happened after about 30 total hours of cutting with the Laserboard (GLCD installed) working on a Linux laptop via Lightburn. I’d start up a job, either engraving or cutting, it didn’t seem to matter the settings or material, and four to eight minutes into the job the GLCD would begin to display a constantly changing stream of alphanumberic, ASCII, Chinese and other characters. Turning the control knob on the GLCD interrupted the flow of characters. To verify that the problem was not OS specific, I replicated the problem with Lightburn on Mac, Windows, and another (separate) Windows machine.

OMTECH “Red” K40 with red dot, C3D laserboard, air assist, two cameras, 5 gallon bucket cooling system. Lightburn on Linux Mint, Ubuntu, Windows 10, and new MacBook Pro. The compressor, laser, and computer are run from three different 15 Amp circuits in my shop.


  1. Completely unplug all Laserboard connections for 15 minutes.
  2. Reset Laserboard via button and replace firmware/config files on Laserboard SD card. Verify function with Board Indicator Status LEDs.
  3. Improve wire management with better arrangement of zip ties in and around the PSU; I particularly tried to route the GLCD ribbons separately from all other wires. Shielded the GLCD ribbons. Tightened and hot glued connections where applicable.
  4. Resumed workflow and 20 hours in, no problems. If I can make it past 50 hours I think the problem will have been solved.

My electrician neighbor and I easily replicated the problem. Once we did that, we repeated steps 1-3 above to fix and it’s been fine so far. We suspect close proximity of wires to the PSU and replicating the problem seemed to point to that as the culprit.

I wish that I could provide more evidence. I tried to post a video of the constant flow of characters but video formats are not allowed and neither are pictures for new users. However, I hope this will be helpful to somebody.

Thank you, Mike

I have upgraded your trust level so that you can now upload photos. Videos can be uploaded to YouTube or similar and linked here.

The LPSU is known for being pretty noisy and as such the entire electrical compartment of the K40 is.

We talk about these measures under the “Scrambled Screen” heading here: