I do not have specific knowledge of the NG however as a generalisation I would expect the FCCs to be powered from their respective AC Buses with no backup from the Stby system.
ALL EECs that I have come across are powered by a dedicated generator that is on side gearbox driven. Before engine start, until the DG is producing power, the EEC is powered by normal AC power. If the DG fails then normal AC power is again the power source.