# Laser randomly fires at 100%

**URL:** <https://forum.cloudray.com/t/laser-randomly-fires-at-100/1076>\
**Category:** CO2 Laser Cutting & Engraving\
**Created:** [February 24, 2023, 11:46pm UTC](https://forum.cloudray.com/t/laser-randomly-fires-at-100/1076 "2023-02-24T23:46:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![trevor](https://avatars.discourse-cdn.com/v4/letter/t/258eb7/32.png) [@trevor](https://forum.cloudray.com/u/trevor)\
**Post date:** [February 24, 2023, 11:46pm UTC](https://forum.cloudray.com/t/laser-randomly-fires-at-100/1076/1 "2023-02-24T23:46:54Z")

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Hi all,  
I have a D.I.Y. build 130W with a Cloudray MYJG-150W.  
Everything has been running great for a few weeks and now the laser will only fire at 100%.  
Anyone able to help with this one?

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**Author:** ![jkwilborn](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.cloudray.com/jkwilborn/32/687_2.png) [@jkwilborn](https://forum.cloudray.com/u/jkwilborn)\
**Post date:** [February 25, 2023, 2:16am UTC](https://forum.cloudray.com/t/laser-randomly-fires-at-100/1076/2 "2023-02-25T02:16:04Z")

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There are two control lines to the lps from the controller…

L-On1 which enables the laser to fire and LPWM1 which is the percentage power.

Without the lps powered up, you can check the L-On1 at the controller or at the IN input of the lps. It’s a ttl type signal, although it will respond to an analog voltage, so it’s range is 0 to 5V.

At 50% power it should read @ 50% power, 50% of 5V or 2.5V… The pwm on a Ruida runs as soon as the machines goes into run mode. It’s constant throughout each layer.

The L-On1 needs to pull L on the lps low to cause it to fire.

These two are easily checked with a voltmeter.

😺