Omtech 150W laser running LightBurn with Ruida controller will not fire under 55%

We are experiencing an issue where the laser is being powered despite the machine being turned off. I’ve outlined some of my observations below.

  • When the machine is powered off, and the laser power is turned on, the laser will begin cutting.
    • It will cut even if the lid is open
  • When the machine is turned on, while the laser power is on, the laser will shut off while returning to the home position. Then the laser will turn on while traveling back to the previously set origin position.
  • When the machine power and laser power are both on and the laser has returned to the origin position, the laser will turn off and remain off.
    • When framing a file from this position the laser will turn on and cut while the laser frames.
    • The laser will cut normally when I send a file from LightBurn.
    • If the machine is turned off while the laser power is still on the laser will activate and begin cutting.
  • The “Test” button on the laser power supply does not activate the laser.
  • There is an illuminated LED on the main board. It’s marked GND and it’s in position 1 in the CN5 group.

Is this new news, as in “it used to work fine and just now went crazy” or old news, as in “we just got tired of this nonsense”.

How does that work? On my OMTech, the “machine power” rocker switch also controls the power to the HV supply driving the tube, so that when the main switch is off, everything is off.

In addition:

  • A second rocker switch, in series with the main switch, must be turned on
  • A key lock switch, also in series with the main & secondary switch, must be turned on

They want you to be sure you want the laser to fire!

Does your machine have a separate switch, independent of the main switch, just for AC power to the HV supply?

If that’s the case, then I’d immediately rewire the main power switch so it also controls the power to the HV supply through the switch that now connects directly to the AC line.

I must unplug the connector from the controller with the L-ON and PWM signals before the Test button on my HV supply will do its thing.

Did you try poking that button before all this started and it behaves differently now? Or is this the first time you’ve poked it?

On a 6445 or 6442, that would be LED 15 and indicates a good +5 V supply.

Opinion: replace the power supply. If that solves the problem, you’re done. If not, you have a spare and we can proceed.

Reason: HV power supplies seem to fail by ignoring / misinterpreting the L-ON signal that should disable them. This should not be possible, but we’ve seen it in many different machines.

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