Ok, so I am still confused. Both example sketches contain this block:
// anod pins
int ledPin_a_1 = 10;
int ledPin_a_2 = 11;
int ledPin_a_3 = 12;
The single-bulb demo passes a value of 0 into its DisplayNumberSet functions as the first parameters, which will set the anode to ledPin_a_1 and hence use digital I/O pin 10 on the Arduino. However the pin that actually receives the 180V is anode A4 not anode A1.
So my question still stands: what Arduino digital I/O pin corresponds to anodes A1-A4? The code snippet above implies: A1=10, A2=11, A3=12 and I guess by extension A4=13. However the single bulb sketch uses 10 and A4 turns on so that means A4=10 and therefore I have no idea what the other 3 are.
Is the silk screen wrong maybe? Is it that the right-most anode pin is really A1 rather than A4? That is the one that gets 180V when I use pin 10 at least.
Sorry if I'm being really stupid here.