Replaced Diode Laser Now It's Always On

I ordered a Laser Tree LT-80-AA 12v Kit A on Amazon ( to replace an ORTUR LM2 15W. It arrived today and I’m running into an issue. I’m experiencing trails between cuts/engravings and 10% power engraves as deep as 50% which is as deep as 100%.

I’ve posted this query to a few places online and gotten no helpful responses. You can see a couple of images of the test cuts here (

Any thoughts?


What is the value of S Value Max in Device Settings?

Also, confirm that you can modulate power by testing the Fire button in Move window. Does increasing/decreasing power there affect the brightness of the laser light?

S Value is 1000
Test fire appears to fire at 100% even when I have the power is set to 0.01%.

How did you wire the laser module? Did you take the existing cable and insert into new laser module?

If so, compare the old and new laser modules and make sure the pin assignments are the same.

Yes, I used the existing cable.
Looking at the images I’m finding on the following pages:

As there is only one way to insert the 3 pin plug, based on those images it appears that the pin configuration is the same. Red = Power, Black = Ground, Yellow/White = VCC

The Ortur information is likely to be correct but I suggest you confirm on the Laser Tree side. I’ve seen a number of variations of the board so it’s possible that something is different than the photo on the linked site.

If you confirm that the pins are correct then I suggest you test voltage of the PWM signal coming from the controller. Confirm that it varies with power from 0-5V. If it does, then likely the laser module is defective.

Okay, will do. I’ll have to wait to verify that tomorrow. I’ll reply once I have confirmation.

If you wired it like this it will always be on.

In all probability there is a pwm signal in the group… Likely the ‘Yellow/White’… as stated in the last linked thread.


I am a bit confused at the cost of this laser. When I search I get a price way, way below Amazon. Are there a lot of clones about just under £39?

Make sure you are searching for the specific model. It looks to me like Laser Tree has a ton of variations of their lasers, some with very slight differences in naming. I suspect they may also do OEM manufacturing with variations to suit customer needs.

Since my last response, I reached out to the manufacturer but never heard back and in trying to exchange the laser was told they’d only do a return, when I got my money back the price had increased $50.

Laser Tree reached out to me to try it again and offered an additional discount for my trouble. I agreed, but the new module had the exact same problem.

I stayed in communication with them and they concluded it was a faulty driver board. They sent me a new driver board which I received today, since I had to swap out the driver boards I had the chance to double-check the connections; the pins “match”. Power and Ground both match so presumably the 3rd does also. On the Ortur board it says VCC and on the Laser Tree board it says 12V.

Unfortunately, after swapping it out… nothing changed. I’ve messaged them with the latest test results which match the first. We’ll see what they say next, but now I’m wondering if it’s something to do with LightBurn after all, but I’ve no idea where to proceed from here.

Did you ever do the voltage tests on PWM and Ground leads from controller? Test voltages at 0, 50, 100% power. You should get roughly 0, 2.5, and 5V respectively. If not, something is not right.

This is easy enough to check.

Setup a test burn with 3 layers, line mode, with 0, 50, 100% power setting. Then do “Save gcode” in Laser window. Can you post results here?

I’ve misplaced my voltage meter, I’m sure it’s around somewhere, I’ll have to see if I can find it. As soon as I can find it I’ll post the results. I saved the GCode though, hopefully, this is how you meant.

; LightBurn 1.2.01
; GRBL device profile, current position
; Bounds: X0 Y0 to X66.5 Y19
G00 G17 G40 G21 G54
; Cut @ 1200 mm/min, 0% power
G0 X0Y0
; Layer C00
G1 Y19S0F1200
G1 X21
G1 Y-19
G1 X-21
; Cut @ 1200 mm/min, 50% power
G0 X22.75Y0
; Layer C01
G1 Y19S500
G1 X21
G1 Y-19
G1 X-21
; Cut @ 1200 mm/min, 100% power
G0 X22.75Y0
; Layer C02
G1 Y19S1000
G1 X21
G1 Y-19
G1 X-21
G1 S0
; return to starting pos
G0 X-45.5Y0

Unless you can answer some of our more technical questions this isn’t going far. 13 posts and I still don’t know how it’s wired and how it supposed to be wired.

If it was working and you changed it out properly, it should work. The replacement didn’t work either, it’s more indicative you have it wired incorrectly.

Good luck


The g-code shows S0 for 0% power, S500 for 50% power, and S1000 for 100% power which is what would be expected based on your GRBL configuration.

So not likely to be a LightBurn issue.

“VCC” is power. Do you mean PWM?

VCC term commonly used as logic power. If as a fact connected to VCC - it is logic always on.

Take a picture of both ends of your connection.

Red should be +12V and white = PWM, not VCC.

Well that’s something at least.

That may be my confusion/misread of things. Made assumptions based on limited visibility. The Pins on the Ortur were labeled as PW[?], GN[?], and VC[?] because they had a heat sync covering the 3rd character.

The Ortur wiring was red to PW[?], black to GN[?], and white to VC[?].

The new LaserTree driver board is connected red to PWM, black to GND, and white to 12V.

Here are the markings for the Ortur.

Here are the markings on the new driver board I installed from LaserTree.

Here is the LaserTree connected.

It’s nice to have color wires because you can tell where they go, but you can’t depend on the color being an identifier…

Usually it red for 12V or VCC, Black/green GND and the ‘left over’ color for PWM… One of mine has this flipped over…

The cable has a ‘keyway’ on it’s outer side that allows only one way to insert it… You need to check that whatever wire goes to the PWM also goes to the laser PWM.

Plug it into the Ortur, and see which wire, VCC, GND or PWM, is what color, then follow that to your laser.

Make sense?


Here VCC is +12V
Cable appeared to me matching both lasers. No need to change anything.

If you feed 12V VCC to PWM logic input - there is a good chance that PWM input is blown.