I’m installing a MK3 heatbed in the Vertex. The mainboard has two pins for the thermistor and 4 pins for the heatbed. I have this power expander (http://reprap.me/heatbed/power-expander.html) which only uses two of the pins to enable the power for the heatbed. Which of those 4 pins do I need for this?
They are paired so you can use the 2 external (safer). If you look they’re labeled – ++. The power expander doesn’t drain much current so using one - and + pin is enough.
