Hi Wilson.
Water protection is on and no interlock issues.
Thanks,
Brian.
If itâs set to 50% power by IN held at 2.5V, then it should lase at approximately 50% power. Your ma meter does not show anywhere near, Iâd find it hard to believe you can cut something under 1ma with that machine.
Mine runs, at 50% power, drawing about 7 or 8 ma. At 15mA Iâm getting full power out of the tube. Itâs a 50W 1000mm tube.
I can find connections to the board, but no explanation of how itâs supposed to work. Even the few articles I found donât give any kind of explanation of what they are doing.
Are you sure the ma meter is correctly in-line with the return? A tube should be able to lase continuously at 50% power alone with drawing more current.
Iâd suggest temporarily wire the L through a switch to ground. This prevents it from lasing if off, it on it just grounds L. I doubt you are running at 50% power. Iâm suspicious youâre using the pwm in some way you are unaware of.
I can find no relative documentation on it, except it say L for laser enable. There appears to be no schematic I can find, so I canât even tell how these outputs are dealt with.
Many times these set the power (via a knob to IN) and the tube is turned off/on. I canât understand why itâs lasing at only 0.4ma.
L should not go low until it needs to lase, so I donât know what itâs doing. Makes me think we donât know what the control board is doing.
What makes it lase is the pwm on most diode or RF lasers, it just follows the pwm for on/off. Most implementations use only pwm, as itâs should only produce pwm signal when it needs to lase. If you enable it to lase, but pulling L low with a switch, then the only thing allowing it to lase is the pwm.
Make sense?
Correction on my part, sorry for the confusion: that first successful divider test was actually 4mA, not 0.4mA - I mis-typed it a few messages back and itâs been carried forward. So the tube did draw a more plausible current for actual cutting, not the tiny figure that got quoted.
Good suggestion on wiring L through a manual switch/direct jumper to ground, left on for the whole test - that removes the Cohesion3D from Lâs side entirely, and means the only thing controlling firing is whatever I send via M3 S through my IN circuit (currently a resistor divider + BC547 transistor, gated by a separate PWM pin). If it fires and properly scales with different S values under that simplified setup, that confirms the IN/PWM side is the only remaining piece to sort out. If it still doesnât fire cleanly with L guaranteed low the whole time, that points squarely at the IN signal itself.
Will follow up shortly.
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Even at 4ma, 100% power would only be 8ma, so something isnât making sense.
If the controller generates pwm, it will lase with L through a switch to ground. If itâs still lasing when it shouldnât, it must be generating a pwm signal. That or a bad lps, which I doubt.
Compare that to my Ruida, anytime itâs executing a layer, itâs produces a pwm signal. It only lases when L is pulled low by the Ruida. Maybe that helps or doesnât, I donât know.
Hang in there, weâll figure this out. Too bad information on your controller is so difficult to come by.
Update - got it working! Wanted to close the loop since you both put real effort into this.
The breakthrough came from finally inspecting a genuinely identical PSU (same ZYE MYJG50W model) on a working machine I put in a suppliers factory for cutting plastics - still running its original OMTech board, not a Cohesion3D, but the PSU-side wiring turned out to be exactly the reference I needed. Key findings from that machine:
- Only P, L, IN, and G were actually connected on the PSUâs 6-pin block - 5V was left completely unused.
- The boardâs âLaserâ output connector was just 2 wires: G and IN.
- L was wired back through the boardâs own power-in bundle - suggesting L is meant to sit permanently satisfied/grounded, not actively toggled per-move.
That confirmed something important: on this PSU, L should be a permanent, solid connection to ground, not something the controller needs to actively switch. My mistake early on was relying on a wire that showed continuity to ground but wasnât providing a low-impedance enough connection in practice - a hand-held direct jumper would light the âLaser Signalâ indicator, but the same nominally-continuous wire, left connected, wouldnât reliably do the same. Adding a second, dedicated ground wire alongside the existing one on L (sharing the terminal) fixed that permanently.
With L now genuinely solid, the remaining piece was IN. Confirmed a fixed resistor divider (5V-10k-node-10k-G, IN tapped at the node) does produce real firing current - but being fixed, it fires the whole time L is satisfied, which is now always. So IN needs to be gated on/off in sync with actual cutting moves, not just left fixed.
Final working circuit: the divider stays as above, but the node also feeds the collector of an NPN transistor (BC547), with the emitter to ground and the base driven from a Cohesion3D GPIO pin (P2.4, via a 1k base resistor) - using Smoothiewareâs native laser_module PWM output. When the pin is inactive (G0/idle), the dividerâs own resistors hold the node high and safe. When laser_module drives the pin (during G1 cuts, per the S value in the job), it switches the transistor on, pulling the node - and IN - toward ground, matching what this PSU needs to actually fire.
With both pieces correct - L solidly grounded, IN gated only during real cuts - the laser now fires only where it should, with no pre-target burn line, and switches off cleanly afterward.
Thanks again for sticking with this - the RMS-meter explanation, the P/L/IN clarification, and the push to find a working reference all directly led to the fix.
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Not sure I follow what you did, but if itâs working correctly, then thatâs greatâŚ
And of course, youâre entirely welcome for the assistance..
Have fun and good luck.