Laser Firing Question #742

I have a k40 with a digital control panel and have upgraded to your Cohesion3D control board using light burn. The laser will fire using the test button on the LPSU, the laser will fire using the test fire button on the digital control panel. The laser responds to changes in the output on the digital control panel. When I run a job from light burn the lights on the C3D controller all appear correct, fire light flashes appropriately. When I jump the L to the G on the LLPSU, the laser does not fire. I double checked the connection of all cables. Including the connection to the board and the sequence of the cables, they appear as per directions. When I run a cut file, no power is going to the L terminal on the LPSU. I tried using the L and G terminals on the board as you instructed in the prior post, still no power going to the L terminal on the LPSU. Any help would be appreciated.

I have created a new topic for your post per forum etiquette. It is better to do this than to piggyback on an existing topic.

If this is true, then your issue is on the LPSU side and not on the board side. Until you are able to touch the L and Gnd wires from the LPSU together and have the laser fire, you should not proceed.

It is possible that these bypass certain protections, like a water flow sensor, while the L and Gnd wires do not, or it is possible that your L and Gnd wires are not properly making contact in the screw terminals.

These are the things you should investigate first.

You had originally responded to:

You did not have to do this proposed solution yet. Once you are able to get the laser to fire by touching the L and Gnd wires from the LPSU, then I would recommend putting everything connecting to the board back to the way it was and going from there.

1 Like

Thanks for your help, let me try to chase those down tomorrow.

I verified the continuity of all wires coming into the LPSU and could not find any wiring issues. I sent a note to the seller and manufacture asking for help as to why the G to L is not firing the laser. The old power supply had the plugs and the new supply had the wire pots. The only way the digital controller will work is by connecting what was the K+ wire to the Low Level Laser Output (option is High Level which doesn’t work), would that have any effect on changes to the firmware? Thanks,

I’m curious, is that new power supply a standard MYJG-40?

I believe it is.

Do you have better photos of the wiring? The P needs shorted to ground for it to work if you don’t have a water flow sensor.

Sometimes a lid sensor is wired in that spot as well so make sure the lid is closed. Additionally, the ‘laser on’ switch must be turned on from the front panel.

This is often how they enable and disable firing with the panel, by using those two pins, so if they aren’t wired correctly or shorted, the laser won’t fire. If shorting these two allows it to fire now, further investigation of how it’s wired is needed and must be corrected for safety reasons. Even a simple toggle switch to disable firing would work.

This is the wiring diagram for the LPSU

WP is the water protection, and I have that jumped to the ground. The L is where the K+ wire is connected. Everything else is the same as the original power supply. Digital Control works fine, including test fire and adjustment of the power output. There is no saftey switch on the lid. Test fire from the LPSU works fine. But when you ground the L on the far right wiring block on the LPSU the laser will not fire and the Cohesion3D board will not fire the laser, but does move the head as expected. Cohesion3D says that until I get the laser to fire when the L is grounded, it’s either a wiring issue or a defective LPSU.

The seller has refunded my purchase and to not bother returning the LPSU. I ordered another with the terminals that matched my OEM supply. Crossing my fingers. thanks for your help.

Please keep us updated. I’m really curious if the LPSU came defective.

It’s really hard to tell how everything is wired up from the ratsnest in the pictures you originally provided, but if the laser power panel button fires the laser, then there should be a way to replicate that from the board.

I’d strongly recommend not attempting an LPSU swap yet, as that can complicate your life even more.

I have not been able to get anyone with a clear understanding as to why when I ground the L to G on the LPSU it does not fire. Cohesion3D support says if that does occur, the controller will not fire the laser. From the digital controller aspect, it’s doing everything correctly from controlling power levels to activating the test fire. I hate to try another LPSU, but don’t have any other diagnostic path at this time. The manufacturer has not responded to multiple requests and the reseller provided no feedback other than a full refund. If anyone has any other suggestions, I am open to trying something else.

Don, can you confirm the connector block on the right side matches these connections as shown in the image below?

And that when you short the L to the G the laser does not fire?

Pete, yes, that is correct.

Thanks, Don… Just wanted to confirm. As others have said, if connecting L to GND doesn’t fire the laser, it really does point to an LPSU issue that needs to be solved.