Laser firing continuously when signal connector unplugged

Thanks to some kind advice from @jkwilborn I unplugged the signal connector from the LPS, to narrow down the cause of my laser not firing.

After I unplugged the signal connector, I powered on the machine. It began homing as usual. But when I briefly pressed the Test button on the LPS, the laser fired on full power continuously until I turned off the machine.

It would seem the LPS and laser tube both work.

Yet when I plug the signal connector back in, restart the machine, and try to Pulse the laser via the controller, nothing happens.

  • Is that the expected behaviour of the Test button?
  • Where does this leave me?

It should only lase while the test button on the lps is held down. It should shut off once the button is released.

Test button on the lps, causes it to lase at 100% power…

If it doesn’t quit lasing when you release the button, you have an lps problem. Need to find a replacement…

The Ruida has two control lines to the lps, L-On1 → L and LPWM1 → IN.

The lps has a P input for water protect, it must be held low.

Can you check these input signals… voltmeter works…


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Thank you!

After you pointed out the laser control lines, I looked closer and there was a loose connection :grimacing:

Great… many of these seem to have the hot glue holding the pin in place… they miss a screw, then hot glue it and it works… for a while.

Glad you’re back up…

I went ahead and marked it solved.

Have fun


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