Printing With An LCD Controller (prusa i3)

hey everyone i new to 3d printing and i just bought a prusa i3 here: [www.3dprintersonlinestore.com]

i bought it with a 25$ LCD controller and sd card slot. When i got everything i immediately assembled it but nothing would turn on (except a little power source light) unless i plugged it into the computer and then i was able to control it with the LCD screen but as soon as i unplugged the computer everything shut off.

I don't know if this is standard or maybe i did something incorrectly but is there a way to use it without a computer?
thanks!

Which most likely means you don't have a power supply connected to the RAMPS, or you made the wrong connections, or you forgot to plug in the AC cable. I think it would not even print anything.

Edited 1 time(s). Last edit at 08/23/2014 04:36AM by alvinhochun.

The RAMPS is supposed to power the arduino through diode D2 if it is installed. However, my first RAMPS had some kind of flaw where the power didn't get through. I solved the problem by connecting a DC barrel connector with a short wire to the power supply wire where it plugged into the RAMPS. Then I just plugged the barrel connector into the arduino. I tapped into the 5 AMP rail, and I triple checked that I had the polarity correct.