I’m watching these youtube videos explaining PWM control of lasers and it seems pretty intuitive. 5V peak-to-peak variable duty cycle, with 100% duty cycle meaning “full power” and so on. But when I send full power from LightBurn to my controller, the most I’m seeing is around 10% duty cycle at 1000 Hz (100 uS @ 5v, 900 @ uS 0v; period = 1000 us, 1 ms). When I send 50% power, I see 5% duty cycle at 1000 Hz. I see the same thing when I save gcodes to file and send them from an offline controller.
The laser is a comgrow Z1. The jumper was changed from “Auto” to “ON”, and the 12V laser power output on the 4P laser connectors changed from a pulse wave with a peak of 12V and frequency of 1000 Hz, to a constant 12v signal. The PWM did not change.
I don’t understand how to use the 3P connector, and it seems like that might be what my laser uses.
It’s helpful if you answer directly as many questions as you can.
Keep in mind that we don’t know your machine or what you are trying to do/fix as well as you do.
So bringing us up to speed on the details of the machine is paramount to us helping you.
So this is a diode laser.
I can only guess that you changed out the stock controller and now you are trying to get it working again?
Was it working before you made these changes?
Do have a wiring diagram for your current setup?
Did you change out the stock controller?
What controller is that?
Do you have any technical information on that controller? Schematic?
No idea what this jumper is and where.
No idea what 4P connectors you are referring to.
What PWM are we referring to?
I don’t either but with more information we probably can figure it out.
In the dialog in the first image lightburn has Laser Power Max (S) set to 1,000
In the second You can see that GRBL has Laser Max ($30, aka Spindle max RPM) set to 10,000
I think this is where your ‘unable to get more than 10% of max power’ issue lies…
Either lower $30 on your controller to 1,000, or change the max power value used in lightburn to 10,000.
EDIT: IT IS $30 and not$32 as I originally said here…
Looks like you’re right. Changed it as the s-max power message bubble instructed so that $32 in the machine settings would match, and PWM was showing full 4.94v 100% duty cycle at 100% power.
Now the laser still doesn’t turn on, but I think it might have been damaged when the first controller went down, or I may have damaged it trying to get it to work with this controller (The way the laser power and board power connectors would seem to fit together, applies reverse 12V to the laser power input wires).
$30 (max spindle speed) and S-value Max have to be equal. This was your original power issue as @easytarget stated, however he mentions the wrong variable… probably a typo…
$32 sets the control board to laser mode… This turns the laser off between moves.
Generally we don’t turn the spindle off, just lift it up and move it… an operation that really can’t be done with lasers.
Might want to read over these documents for a grbl machine setup.
