Converting a 3812 interface board to be 3712 compatible:

If the 3812 board uses a 2708 (all three regulators installed and 
W11, W12, W17 installed), then conversion to 3712 requires only the
removal of W10 (disconnects one-shot from bit 0) and installation
of W9 (connect real data to bit 0). 

Of course, the 3712 EPROM should be installed as well.