Most control blocks activate on the opposite side of their display screen, the Power Supply Control Block appears to work in reverse. To fire forward the screen is facing the 'rear' of the vessel.
Beam fires in the rear direction with panel viewing to the rear. Other Weapon systems have to be the other way around for that.
this is true for Power supply and drain Beam
(shield beams cant be checked - they do not render for me)
{F647}