Can anyone help us to understand why we get these random dots that seem to have some correlation between the power and the speed? They are most evident on mirrored acrylic and slate and we are trying to figure out the cause. This is a material test we ran on the mirrored acrylic:
We have seen the lps lase when the signals tell it not to lase… @ednisley has caught this on his scope…
ooh, hey thanks for that, I was searching the incorrect terms. found an old thread Weird dots all over my engraving - #243 by JustAnotherLaserGuy that points to a bad lps. Any ideas if there are any recommendations on replacement lps or any line filtering that can be done?
My sample of three HV power supplies with different labels on the outside shows they are identical inside:
There’s some evidence suggesting the power supplies in (much) higher priced machines are different and behave properly, but those supplies aren’t available from the usual sources.
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Nice, thanks for your documentation there!
I found it weird that as the speed increased the power the dots showed up at moved. I figured it was power related but wasn’t sure if it was dirty/EMI related or just bad/cheap LPS.
Guess we need to find a new/better LPS or something else.
Was this rectified for you by replacing the LPS?
This is exactly what I have had going on since the very beginning with my machine. It has forced me to stick with a power setting under 13. I mostly use my laser for cutting, so I have just dealt with it along the way. Now I need to do more engraving with it and would love to be able to use a higher power range to speed things up. I still have not swapped out the LPS as of yet though.
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Power supply replacement did not fix the problem for my machine.
Another data point suggesting they’re all alike inside. 
Thanks for the update!
Not sure what you mean. There are probably hundreds of thousands of these out there and most don’t show this anomaly. It might be as you stated previously it’s the luck of the draw. Being Chinese, it’s likely designed close to the specifications anyway.
I’ve fixed equipment for half a century.
If all the control lines tell a module to do one thing and it does another, that module is bad. I don’t know what else to say.
I suspect @JustAnotherLaserGuy got another lps with the same issue.
I suppose it is possible I just got another bad LPS. For now I will just be stuck using this machine primarily for cutting, or for slow speed engraving (although even lowering the power and speed does still leave some less visible random dots on materials like acrylic). I guess I can’t expect much from a $3k machine
I’d suggest you contact the vendor and see if they will swap it out with no or little cost to you.
I have a $2K machine, works fine and have never had this issue. @ednisley has seen or had it, so he’d be better for a response.
Thanks @jkwilborn. Tried going through Omtech support but they were no bueno.
I understand. I never had a reason to speak with them while my machine was in warranty.
One of the other users (@DougL with a K40) suggested to try it using the analog output of the Ruida instead of using the pwm. I don’t see how this would make a difference, but it’s a cheap attempt to see if it fixes it. You can just swap the wire from LPWM1 to L-AN1 to test his theory.
I thank @DougL for sharing his input.
Ok, I will give that a go and see what happens.
Gave it a shot and unfortunately no change.
I don’t’ know what else to advise… I didn’t think changing from digital to analog would matter, but I’ve been surprised before with this stuff.
I think you’re back to the original issue.