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Different K40 with different wiring

Hi ...several probs down here ...cause i'm a rookie and my k40 is totally different from what i was able to see in the tutorials ..i'm also an electronics enthusiast ..trained with pcb and soldering but with a simple to replicate project ...here i'm in front of something too big for me

hope you will help me

i've tried to follow these instruction but with no luck

the gerbill showed is different and also my wiring and connctros are different (at my eyes)

Installing the Mini Gerbil 2 on the K40 power supply Type 2


so i'll attach the photos of my old controller and the power supply installed


i've got DAC OUT (?!?) with 3 pins

power to the old board is 3 pins

OUT of the old board is 4 pins


probably for you is easy ...for me is a bit thrilling 🙂

link me to a topic ...if it was already solved ...i was unable to find a solution in the forum ..but i didn't open all the topics


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Hi Matteo,


It seems you have a very new Chinese controller board but the laser power supply (PSU) is still the same. That's good news because you should be able to use the MG with the PSU.

X-motor - goes to the x motor connector on the MG (Mini Gerbil)

Ribbon cable (endstops and Y motor) - goes to the ribbon connector on the MG

P+ -  is the protect loop. Just bridge this connection. Used in the scenario of a water protect or laser lid switch.

OUT and DAC Out -  follow the leads and take photo's where the originate from so I can help you further.

One should be the laser power pot or digital panel and the other should be a laser enable switch (LO pin on the PSU power connector) .

24VDC, GND, 5VDC, LO are on the PSU connector (your last photo) - that should connect to the MG. Question is how much power does the laser unit require? Since the last photo shows and empty power (4pins) , I wonder if an external power supply is used for powering the motors? If you can have a look and take a photo of an external power supply then that would help to understand what the current configuration is. That would help to understand how to move to the use of the PSU with empty power connector or whether we need to use the external power supply and add some wiring. At this moment, that is unclear to me.

Thanks Paul

matteo oddone has reacted to this post.
matteo oddone
Cheers, Paul awesome.tech

oh wow ...thank you so much ....i'll work on the k40 on monday ...i'll post the request photos ...now i fell more confident ....thanks again 🙂

Paul has reacted to this post.

a bit late ...but here 🙂



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Hi Matteo,

From what I see is that you have an additional power supply. The reason for that is, the board in the K40 seems a very new design which probably does not work well because of the laser  tube noise. The good news is that you don't need that additional power supply. You can remove the wiring and just use the Laser power supply (5V and 24Vdc) with the LO laser on signal. These are 4 wires from the laser supply to the MG board. The plug you need is an MTA156 plug, don't solder the wires directly but use a plug. MTA156 is the series which stands for TE connectivity with a pitch of 156 or 0.156" (3.96mm)


or https://www.jaycar.com.au/4-pin-0-156in-header-with-crimp-pins-3-96mm-pitch/p/HM3434?pos=10&queryId=d1da594ad4459b003a42ac6dcd35b704&sort=relevance&searchText=3.96

The potmeter can be just omitted since the MG controls the power via software (e.g. lightburn with G code commands e.g. S100 give 10% power). Just plug in the motor axis plug and Y axis/endstop ribbon as per instructions. Make sure you  bridge the P+ and GND connection (water or loop protect) otherwise the laser won't fire.

Let me know how you go.

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Cheers, Paul awesome.tech

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