I am new to building the printer from scratch and still waiting on a few parts(bearings and belts). I got the Mega with ramps1.4 and Drv8825 drivers with the 12864 Full graphic display from china.
With a steep learning curve I managed to install marlin (Marty's version) on the board.
When the mega is connected via the USB with display it all seems to be working fine I can see the menus and click through them.
When I disconnect and only run from the 12v power supply the display only shows a blank display but is blue back-lit. I can not see anything but this not the case if running off the usb.
Just some notes I have not connected any end-stops, motors or sensors to the ramps1.4 yet as I was just testing still.
Thanks in advance