I have a LY Group 3020 bought in 2020 from AliExpress. I'm upgrading it and figured others might like to learn from the details.

Would love to read threads and exchange comments with anyone else that has one of these machines and wants to hack on it.

My CNC came with a proprietary USB-based controller that only speaks to Mach3 using a plugin driver (BL-USBMach v2.1). I don't like this controller and driver nor needing an extra copy of Windows to maintain Mach3 (I run Linux primarily.) This is the primary reason for the upgrade.

The controller will be swapped out for a GRBL-based microcontroller (partly of my own software design), a Huan-Yang VFD, and Leadshine stepper drivers.

The wiring topology for these kit machines is roughly:
[Steppers/Limit Switches] --- parallel port cable --- [Controller] --- usb cable -- [Windows PC w/ Mach3]
[Spindle] --- 4-pin aviation connector & cable --- [Controller]
[Tool Sensor] -- 2-pin GX-16 aviation connector & cable -- [Controller]

The male parallel port on the gantry and the female parallel port on the controller are themselves an obsolete component: Kycon 37X-92240-24-XJ. I can't even source this component through DigiKey or Mouser.

To access the steppers, I need to disconnect their wires from the port on the gantry. Before I did this, I mapped out the parallel port in case anyone else wants to salvage the controller and its hardware.

The 24-pin parallel port I have mapped out using a multimeter probe:
1 - Stepper X - red wire
2 - Stepper X - blue wire
3 - Stepper X - green wire
4 - Stepper X - black wire
5 - Stepper Y - red wire
6 - Stepper Y - blue wire
7 - Stepper Y - green wire
8 - Stepper Y - black wire
9 - Stepper Z - red wire
10 - Stepper Z - blue wire
11 - Stepper Z - green wire
12 - Stepper Z - black wire
13 - GND }
14 - GND } for limit switches
15 - GND }
16 - Z-limit switch (middle NO contact)
17 - Y-limit switch (middle NO contact)
18 - Z-limit switch (middle NO contact)

Afaik, the six remaining pins 19-24 are unconnected on the gantry. I do not know if they have reserved functions on the controller.

More updates to come...