I have a Prusa Reprap i3 clone. It prints very well from a SD card. When connected to a PC by USB, (with mains power off) the video screen lights up, the USB green light comes on,but nothing else. As a complete newcomer to 3D printing I need some guidance for what is probably a simple problem. I am using Repetier.
It probably don’t get enough power through USB only to turn on the screen?
USB only should be fine for firmware uploads, but you need mains turned on to use the printer.
@Peter_Hertel Thanks Peter, therein lies the problem,it prints from SD card with power on but will not respond to PC even with the power on. It seems that the PC “sees” the printer but can not command the printer.