Here is a weird one. I have been using my laser without issue for about a year now. I have a rambo board using pin 45. Today as it finished the job it went to zero and sat there at 100% power. I used the kill switch to stop it. The weird part is its stuck on, every time I reboot the machine the laser comes on at full power. I have used “reset” on the board, cycled the power, removed and reinstalled the laser wires at the laser but nothing is getting to turn off.
Looking for suggestions to narrow this down. it has to be a board or wiring failure? Seems unlikely it’s a failure internal to the laser that would cause it to fail on?
That doesn’t sound good. Assuming it is a standard type of laser module, disconnect the 3 wire connector at the laser, then connect ground to both the negative and the pwm signal pins of the laser followed by the 12V (or whatever supply voltage you are using) to the positive pin of the laser. If the laser fires up then the control circuitry inside the laser is fubar. If it doesn’t fire up then your problem looks like your board pin 45 is not switching off. It is not impossible for either item to fail ‘on’.
Thank you, let me make sure I understand you. Basically we are trying to power the laser from a stand alone power supply to take the board out of the problem. If the laser is working correctly it will only fire when powered up and receiving PWM signal. Since the PWM signal will be grounded it should not fire, if it does its dead.
If the failure is on the board side then i should see steady voltage coming from pin 45?
Pretty much - yes, power the laser without the Rambo and tie the
PWM pin to ground - that should prevent the laser from firing.
Some controller boards do funny things to their output pins during the boot sequence, but once it has finished booting you should ‘see’ zero volts on your PWM signal line (pin 45) . Send an M5 to ensure the laser should be off and if there is any voltage on pin 45 then you have a problem with your uP
I am having this issue now on a SKR PRO 1.2, as soon as I plug in the cnc, the laser comes on and wont shutdown with any commands (M5 or M107 S0), I am using the PC9 Pin for my laser and I’m assuming the pin is not shutting off. Any recommendations on how to fix the issue of the laser not turning off?
When this happened to me I discovered it was from a break in the PWM line. When the PWM is grounded it shuts off the laser so if left open the laser has no command to shut off and jus fires away. If you can’t find any breaks in your line I would dive into Mike’s troubleshooting above. Good luck!
…which begs the question as to what happened to the old PWM pin?.. is it possible that you have a dodgy plug or wiring that would allow the PWM signal line to come into contact with the +12V supply to the laser? …that would do it, there is not normally any protection on the uP output pins and they are 3v3 data lines, maybe just about +5v tolerant but definitely not +12V !.
Yeah I am clueless on what happened to the pc9 pin, I did double check the connections and wiring, nothing there.
I don’t know if it would affect it but I had some issues with static once I got my dust collection setup until I figured out a grounding solution, I am guessing of course.