Line connection “Prusa i3 complete production process” 3D DIY | August 13, 2015 | 0 | by leon Step 1 switching power supply wiring, yellow, blue, Brown, 220V 220V ground fire line and null line, respectively. Two sets of red and black for 12V switching power supply output. Step 2 Fixed Control Panel and switch the power supply to the printer Step 3 control RAMPS wiring diagrams all connection Well, all the wiring OK, on the back can be debugged. Debugging procedures will not be detailed here, We can refer to Mendel i2 tutorial . The methods are the same.