I am the author of this thread asking a wiring question, and then later on discovered a fix by reading up a ton of other articles. I think it worked a few times, but I can’t be entirely sure I connected it exactly as I mentioned, things no longer work right now. With the following connection (that I claimed to work), the laser beam would keep firing even when PWM is idle at 0V (tested with multimeter).
Even when I completely removed all wires from MKS DLC32, the laser beam would kept firing with the above connection (until I disconnect L from P). I am 99% sure that the laser PSU is broken, but I need some expert opinions before I go out to buy a new PSU due to my own stupidity.
You’ve got the laser enabled wiring L to ground. I ran L to a manual laser enable switch to ground. This allows you to disable the lps from the console.
If IN is 0V, then it should not lase…
Any voltage on IN should result in an attempt to lase at that current level. This is exactly like some of the newer Monport machines with grbl boards operate.
I’d suggest you install a sensor to monitor coolant flow… or pressure sensor that goes low (active) when there is coolant flow. This should be wired to the P input… If you don’t I’d bet money you will toast it some day. I see it all the time.
Considering it worked before, what could have changed?
Hi @jkwilborn, thanks again for your response! I’ve learned a lot from your previous posts on the forum, and I truly appreciate your help.
Regarding the coolant flow, I do have a sensor in place to monitor it (I’m quite nervous about damaging my first CO2 tube ). Now that I suspect there might be an issue with my laser PSU, my goal is to simplify the setup to troubleshoot and identify the root cause. That’s why I’ve only connected L to GND (to simulate the laser lid being closed) and P to GND (to simulate the coolant running – I’ve also confirmed my water pump is actually running).
I’ve tested both the “Active Low” (Method A) and “Active High” (Method B) configurations, as shown in the images below. Even with the MKS controller board completely disconnected, the laser continues to fire with just these connections. I’ve reached out to the Cloudray team as well, and it seems likely that my PSU may be faulty (or I could have misconnected something). I’m still waiting for Cloudray’s response.
What do you think? Are there other connection methods I should try? (Yes the fact that it did work before and nothing external has changed, made me think that the PSU is busted)
Thanks again, Jack and team! I really appreciate your help!
Since I’m using “Active Low” approach (safer some say), we only need to focus on four ports: L, P, G and IN. Bottom right is my wiring, all without the controller board.
The Half-dead PSU
I started with connecting L-to-G and P-to-G, this is to ensure the laser is enabled, and also “water protection” is enabled (this is to trick the PSU into thinking that all the safety precautions are taken, just as a test. In real world use, these must be connected to water-coolant for safety).
Then I placed 20K ohm resistor at R, my intention was to pull-down the IN to 0V, removing the possibility of floating voltage triggering the laser firing.
I turned on the AC to this PSU, immediately it fired the laser, there was no controller board connected at the time. So I thought to myself, this is now gone, I have to buy a new PSU
Since my PSU is spoiled, I thought to myself, heck, I might as well measure the voltage between IN and G, just for fun.
It turned out that IN measured to be 0.97V!! I was expecting it to be 0V because of the pull-down resistor, but that is not the case! (I’m a software engineer so I know next to nothing about electronics)
So I swapped R out for a much lower resistance one, maybe even less than 10K ohm (my multimeter isn’t good enough to measure that one). Then I turned on the AC, it no longer fires!
Then I connect my controller board back to G and IN (PWM), then things started working as expected!
Where I Am Now
I suspect the pull-down resistor is too conductive, it weakens my PWM signals. For 50W laser tube, at 100% power it has to cut 3mm acrylic sheet in 2-pass with speed 400mm/min, that is insanely weak! But that’s the problem of another day, I have ordered a new PSU, hopefully solving all my laser strength problem once and for all.
For now, I am a happy person
Thanks again for all the wonderful help, @jkwilborn (and community)!
Not sure how do I mark this thread as “Solved”, but if that’s what you can help me with, @jkwilborn that’ll be appreciated. My issue is now resolved as mentioned above. Thank you!
With pwm wired to the laser enable, you wouldn’t know what IN has voltage wise. With the need to pull IN low, indicates a faulty lps. It should not lase with no connection to the IN terminal.
Once you get it working properly you can solve most of these, but depending on the category, you might not be able to mark it solved. I don’t think the community laser talk has the ability to be marked solved… I have no idea how this is figured.
It will have a check box if you can solve it at the bottom or within the hamburger menu icon , also at the bottom.
Thanks again for all your help and patience, @jkwilborn. I can’t mark this thread as “Resolved” so I will leave it as it-is. My new PSU is here, I should have no problem with that one so I am fine now.
). Now that I suspect there might be an issue with my laser PSU, my goal is to simplify the setup to troubleshoot and identify the root cause. That’s why I’ve only connected 
at the bottom or within the hamburger menu icon
, also at the bottom.