I tried searching for a solution to this issue within the forums but wound up empty handed.
My problem is this: according to the Arduino IDE, I have successfully uploaded the Marlin firmware. This is confirmed on the LCD screen while the boards are plugged into the computer. However, the interface is only accessible from the computer from which I uploaded the Arduino sketch. Said another way, when unplugged from the computer, and powered by the power supply, the Marlin firmware is not accessible that is, I only have a blank LCD screen when the Ramps/Mega board is unplugged from the uploading computer.
See pics for reference. Any help would be much appreciated.
There arduino and screen run off of 5V, which is either supplied by the usb connector, or the 5V regulator on the arduino mega. The 5V regulator gets power from the 12VDC power.
Your problem is probably due to the 5B regulator on the mega being bad (this is a common problem). In your case, it looks like it’s only sort of broken, because the screen still has some power.
You can either try another arduino mega, or plug the usb into a usb 5V power adapter (like a call phone charger) to supply 5V.
you need to connect all 4 the screw terminals for power on the RAMPS board. (What you point to in picture 2). You only have the connections for the stepper motors connected. The arduino powers from the other side of the circuit.
It is best to connect the way the link shows, i.e. 2 separate cirrcuits from the power supply, but you can also connect your one connection to both sets of screws terminals, by bridging the 2 + connectors, and the 2 - connectors using wire.
Argh. Ignore my post, I was going from a vague recollection of what I have to do to get things to work many moons ago. I just relooked the RAMPS wiring wiki, and I see the 11A connection is only used for heated beds. Your connections are fine.
