Mega 2560/Ramps 1.4 USB connection not found. Power Supply?

I have tried to search, but I am just getting started and my lack of knowledge leaves me not knowing what to search for.

I am working on a 3d printer, and have a Mega 2560. I was able to connect it to my computer and flash Marlin onto it. I have now connected the Ramps board and power supply. Nothing happens when I power it with the power supply. I assume that there is something wrong in Marlin and connect the Mega to my computer via USB. I have tried with both the power supply on and off, my computer wont recognize that it is connected with ramps connected. Is this a common problem? What am I doing wrong?

I apologize that I am probably falling into the category of every new guy that orders one of these things and has problems. I have tried to search but dont know what to search.

Thanks!

What do you expect it to do? What instructions are you following?

I am working on a cobblebot printer. The instructions for the electronics portion of the assembly are lacking much detail. I expected to flash the board, install the other hardware (ramps 1.4, screen, and connect the steppers) and throw 12v to the ramps board and see the screen come on. When nothing outwardly appeared to work, I unplugged the power supply and attached the usb cable to see about updating the marlin code. No lights on the 2560 came on when connected to usb and the computer never recognized it. I turned the power supply on as well with the same result. Question is, does the 2560 have to be bare with no connections other than usb to upload to it?

My Arduino MEGA 2560 uploads fine with the RAMPS 1.4 board attached. My first guess would be a short between +5 and Ground. That would immediately open the 500mA polyfuse on USB power. Try removing the RAMPS board. If the MEGA then works, try adding hardware until it fails. Put in the RAMPS board without the stepper drivers. Then add stepper drivers one-by-one.

Thanks a lot! I'll give it a shot.

Its alive! I did as you said and just kept adding piece by piece. I got everything to work with usb, so I plugged in the power supply. Ive got everything coming along now. Thanks!