Computer shuts down when Ramps connected to means voltage

Mostly Printed CNC - MPCNC Troubleshooting
1

Hi folks,

I was measuring the voltage of stepper drivers with multimeter and suddenly computer shut down and LCD turned out totally white.

I think I probed somewhere else by mistake which caused that.

The current state is:

  • If the Ramps is connected only to computer,
    • LCD Screen works fine,
    • Can see SD card,
    • Able to move axies from Repetier Host and can see the changes on the LCD screen.
  • If I also connect the system to means voltage,
    • Computer shuts down immediately,
    • Screen turns out white
      • I can make it visible again by playing with the LCD backlight potentiometer
      • Steppers does NOT move when playing from Motion menu.
    • Cannot see SD card.
What do you think causing this?

My electronics:

  • Ramps 1.4 Shield - Elecfreaks
  • Arduino Mega - Clone
  • Pololu DRV8825 High Current Stepper Driver
  • 12V-5A Switch Mode power supply > Measured it with multimeter and works fine.
2

It is one of the many issues with the current extremely low quality Ramps imports, It could be anything, driver, either board, USB cable.

Be careful, doing that to your computer too many times can kill a USB port for good.

3

Section on D1 and D2 diodes might be helpful. Sounds like it’s related to what youre fighting.

https://reprap.org/wiki/RAMPS_1.4#D1.2C_D2_-_Diodes

4

After a demanding inspection period, I got a hint pointing voltage regulator.

I just measured it and readings are as:

Power Supply: 12.08V
Voltage Regulator IN: 11.08V
Voltage Regulator OUT: 7.14V

I think it is time to replace the voltage regulator.