No voltage on stepper drivers and LED goes on and off

i am rewiring and checking things as I go along for my MP3DP. I am using a ramps 1.4 and arduino mega.

I am getting power from the power supply. i get 12.18V when i check the terminal.

the first thing i noticed was (with the ramps not attached to the arduino) is the red LED on the shield doesnt always go on and if it does it seems weak.

and when i put my probe on the ground on the terminal and check the voltage on the stepper driver, i get no voltage.

any idea what im doing wrong or what i can do to check? all i have hooked up is the PSU to the ramps board and the stepper drivers attached only. nothing else.

also want to add i removed the D1 diode that is under the stepper drivers bc i wanted to power the arduino with a seperate power supply.

ok so update: i plugged in my arduino witht shield and hooked up the second power supply to the arduino.

when i went to check the stepper drivers i have voltage now and the lights are working right.

so now im concerned bc the diode i removed from under the stepper driver should have been only powering the arduino right? or did i desolder the wrong one and should have removed the one near the yellow componenets?

is the stepper drivers drawing their voltage and amps from the adruino now and not the shield?

To power the arduino separately you remove d1, the one under the drivers… so I think you did it right.

yeah. i just checked it. the lcd, shield, drivers, everything is working now. i guess it just needed the arudino powered to be able to read off the drivers. i was getting power to the drivers bc i made something spark on top of them by accident.

ill continue on i just wanted to make sure i didnt do something worng. thanks for the help.