Help me with my 3D printer

[Baalaji V]

ISSUE: Stepper motors are not working when connected with RAMPS 1.4.


OBSERVATION: The LED lights(LED 2,3,4) in the RAMPS 1.4 is not powering up.


PRATICES: I use Arduino mega 2560 and installed marlin firmware in it. And I bought a RAMPS 1.4 in a local electronic dealer. I placed the RAMPS over Arduino mega 2560. For testing I just connected 2 NEMA 17 stepper motors with RAMPS. When USB port connection is given from laptop to arudino board, a LED light is ON in Arduino board(L) and in RAMPS(LED 1). I use SMPS 12V 20A as a PSU for RAMPS. But in RAMPS the LED 2,3,4 is not switched ON. I checked the input voltage to the RAMPS using micrometer and it shows 11.75V. But there is no output from the RAMPS. The stepper motor isn't powered up.


Also I installed and tried Repetier firmware and grbl but it doesn't work.


When I flashed Arduino with grbl, in this case all the LED lights in arduino and RAMPS 1.4 is switch ON. I use Candle GRBL software to test the stepper motors.


And I replaced and tested with another RAMPS which is bought from Amazon but the problem remains unchanged.


kindly give some suggestions at the earliest.


Thanks and regards
Baalaji V