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Mini GRBL Not Found


I've purchased K40 and tested it with the installed controller and dongle locked software. It works. I can etch / cut designs with the only problem being my inexperience and the clunky software.

In advanced I purchased the Mini GRBL and LightBurn, knowing from reviews that this was the best direction to go. Having installed the Mini GRBL my computer only sees the available com port but not the controller.

I am running Windows 10 Home. Attached are pics of what I am seeing. I do have the digital upgrade to the K40 and so I am also, admittedly, uncertain how to connect the PWM? wire correctly.

Uploaded files:
  • No_Cutter_2.png
  • 20200302_0946221.jpg
  • 20200302_0946301.jpg

Hi, this is a difficult issue since it can have many causes but best is to debug it systematically.

Step 1. Does the heart beat led 2 flashes when powered up (no usb cable plugged in)?

This shows that the processor on the board is running if not then the board is defect and you can exchanged it

Step 2. Swap the USB cable (maybe you have a charger cable only which misses the two additional wires for communication)

The device manager show show a com port which some text like "ST electronics VCP com port". WIN10 does automatically detect the port and does not need a driver.

Step 3. USB ports on the PC or Laptop can become loose because of frequent use so try a different port if the PC/Laptop does have more than one port) or test with a different PC/Laptop

If everything else fails then let us know and we will see if there is another clue or something we missed. Let us know how it went.


Cheers Paul

Cheers, Paul awesome.tech


Thanks for the prompt reply.

Answers to questions/comments:
1) Yes, the board has a heartbeat, that was my first sign of success prior to reaching out.

2) The USB cable is in good working order. I use it on my camera to download photos.

3) I uninstalled the USB port driver and removed the software from the system. The USB Port itself is in fine condition as it drives the laser with the Whisper software and the original controller.

So with the history done and following your guidance, the controller is communicating with LightBurn but....

LightBurn (LB) insists that the home position is located in the front right of the laser, away from the limit switches. This leads to horrible noise and wear as the motors skip on the belt at the end of the travel. Once the K40 has hit those limits I receive only Error 9 until I cycle the power on the K40.

If I move to 0,0 via LB the optics move to the correct back left position. When I attempt to start a job the optics move to the front right again and the job must be interrupted.

Long story short, X and Y on the chinese board were reversed from that on the mini GRBL. The laser homes and moves correctly.

Any guidance on the PWM and how to connect that?

The PWM wire should have come with the Mini Gerbil, it's a short single wire that connects to the furthest right most pin on the mini gerbil and to the IN pin on the power supply.  The IN pin is usually the 2nd from the right pin on the 2nd connector from the right on the power supply.  Disconnect the wire that's on the IN and connect the PWM from Mini Gerbil to it.


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