Need Help Connecting Board to Laser

Machine: 50W CO2 4040 laser engraving and cutting machine with up and down honeycomb working table (From Aliexpress, Seller: LCSpear)

Old Board:
New Board: (Cohesion3D Board)

Firmware: I have a new board and I’m using whatever it came with

Problem/ Question: The 2 cables shown still attached to the red board i cannot figure out where to plug them in to the Cohesion board.

If i understand correctly, out of those 6 cables i know the GND cables need to go into the GND on the cohesion board. Only question is GND on the red board had 2 cables and only 1 in the cohesion baord.

Hi Oscar, welcome to the forum!

Thanks for the photos. I grabbed the pic of the red board and flipped it to make it easier to reference.

The labels are a bit confusing (and colors never seem consistent across different lasers) so rather than guess it would be helpful if you could post a photo of where these wires all go to. They should all run to the LPSU, so a clear photo of that showing labels would be great.

If you check out our LPSU connection guide it should give you some idea of what we are looking for.

After reviewing the guide and following the cables looks like the 2-pin red and black are the ones going to the blue PSU. The other 4 pin muticolored is going to a second psu? pictures attached.

2 Pin Termination (
4 Pin termination (

Full area view (

Am i correct to assume that the 2 pin is he laser fire and ground. The 4 pin are 24v ones and 2 grounds for it?

Oscar, the black wire going to the pin marked TL > LO is “Trigger Low” and will need to connect Laser Fire (L) on the LaserBoard, and the red wire going to the pin marked GND will need to connect to the Laser GND on the LaserBoard.

(Yes, typically the black wire is ground in most circuits, so the colors are reversed!)

This page covering the 6 Pin Laser Power Connector will show where to connect them.

Thank you. I’m assuming the other 4 wires are useless?

Yes, since the LaserBoard has its own power supply we do not need the other wires. That’s what this section from the bottom of the page is about.

The board does not require the 24V nor the 5V wires to be connected. Disconnect the pins or cut the wires from the power plug connector, then insulate them with electrical tape or heat shrink to be extra safe.

Awesome, it’s working perfectly. Now I just gotta figure out why 0,-200 is origin :joy:

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