Unable to Test Fire

Hey y’all,

I have a Shapeoko 3 XXL with a J Tech 7 Watt laser. After I installed Lightburn (on a Mac) and followed all the directions I am still unable to get my Laser to Test Fire. How do I fix this? It will only emit a laser when on CW not on TTL. I’ve spent weeks now fidgeting with the settings attempting to get it running. My settings are as listed:

I am really eager to get this laser up and running since I’ve had great success with the Shapeoko XXL. I’m just tired of having this not working and I’m out of options so I’m turning to the community for assistance. I’ve read all the posts pertaining to this topic and attempted to apply them. Still with no success. Thanks for the help.

Semper Fi,

What do you mean by “test fire”? Do you mean from the laser itself, or using the “Fire” button in LightBurn?

Also, what kind of Mac? I know of one person who was using a new MacBook Pro with USB C connectors, and it caused weird issues with his laser.

The “Fire” button. It will not fire the laser. 2014 Mac book air.


If you run a small square or circle, does the laser fire? I don’t know much about the J-Tech lasers or how they’re connected, so this might be better to work through with them. The Fire button in LightBurn just uses GCode to enable the laser. M3 to turn it on, G1 Sxx where xx is a power value, then M5 to turn it back off.

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