Chinese CNC GRBL controller

Hello (translater google)
Not so long ago, I bought a GRBL cnc controller from Aliexpress and I have a problem with the laser because it does not give the power it should be. As I connected to the old controller, the laser works. Performing the laser test at 100% Pwm is 5volt, but if I want to cut plywood at 100% laser power, the Pwm is 1.40volt and it should be 5volt. Can someone please help me how to fix it ???


CNC 4AXIS Controller MCU32 Bit 32GRBL Stepper Motor Driver XYZA Axis Driver Board Spport 500W Spindle For CNC Milling



MCU32 Bit 32GRBL Stepper Motor Driver
ARM32-bit control board
The running speed is faster, the maximum no-load speed reaches 40000mm/min, the algorithm optimization is better, the vibration is smaller when the machine moves at high speed, and the performance is more stable
X/Y/Z/A 4axis controller 5 driver
This controller support XYZA 4 AXIS, and double Y axis driver ,more powerful driving ability

All signals are isolated by optocoupler
The optocoupler isolation technology effectively increases the anti-interference ability and makes the operation more stable
External 48V 300W/500W spindle
it can connect 48V 300W/500W spindle, not only 775 motor
Split design, control, drive and expansion board may be replaced
limit switch, 5V/12V/24V constant voltage pin
Support to install the emergency stop switch
Can be connected to a high-power driver
Stepper drive subdivision adjustable
Can be connected to 775 motor/3pin ,2pin-2pin /offline controller
PWM/TTL software to adjust power
1* 4axis controller
1* USB cable
1*775 cable
Colour:green
Material:Metal + Plastic