Laser always fire at max

Hi all,

Have a 1390 chinese machine with a 130w laser tube and a Ruida 6445G…

After replacing the PSU i did this connections:

CN5 - PSU:
GND to G
L-On1 to L

i think this is ok, but what happens is that when i send a file via lightburn, no matter if i put 10% power or 50% or 80% it will always fire on max (19mA as i can see in the PSU display)… my engraves are too deep!

can someone help me please?attached goes a pic of my vendor settings on LB.

vendor 3

Thanks in advance!

Can you control the power via the machines console?

Set ‘max’ power to 20% on the machines console and the duration to continuous.

As long as the ‘pulse’ button is held down it will fire.

Just hold it long enough to get a reading.

If you can control it here, then we’ll have to look elsewhere.


already try it… keeps always firing at max!! :disappointed:

If you did that through the console, it should be firing at 20%…

Do you have and know how to use a voltmeter? A scope would be better…

Check between ground and LPWM1 at 50% power setting it should give you about 2.5 volts.
20% power should be 20% of 5 volts or about a volt…

You can do this with the lps powered off so you won’t actually be firing the laser.

This controls the lps. If it’s stuck high, we need to find out why. If not we need to look elsewhere.


thanks for your help,

just did that and when send at 50% power i get exactly 2.5v,
at 100% it goes to 4.5v… so i guess this is not a controller problem right?

That would be my conclusion… It sounds like the lps is not working properly.

Is this the replacement lps (you call it a PSU…)?

Might give them a ring… The other signals have to be working ok or it wouldn’t fire…

Good luck


yes! just came today the Clouray MYJG - 150w

I’d give 'em a ring. They seem to be easy to work with…

You can explain the issue and the steps you’ve taken that make you suspicious it’s the lps.

Good luck


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