10: Connect wires and install case bottom
Connect 3-pin header to Arduino power pins. Two wires — white and brown — connect to GND,
while the red wire connects to 5V.
Connect 5-pin header to Arduino pins 3 through 7. The single green wire should go to pin 3, and
there will now be bare protruding pins.
Press the serial socket (3 wires) from the printer onto the protruding pins 5, 6 and 7. The green
wire should go to pin 5, yellow wire to pin 6, and black wire to pin 7. Pin 4 (reserved for the SD
card socket) is not used…here we've clipped off the exposed pin to avoid installing the printer
socket in the wrong position: