With the APU inop, NBPT will operate normally when,
EXT A is connected, IDG 1 is connected.
There will be a break when EXT A is disconnected and IDG 2 is disconnected.
So if you start both engines NBPT will operate normally.
It's been a long time since we've had a 330 with an inop APU so haven't experienced it lately. However the other day the capt said disconnect EXT power, before the APU GEN was fully on line and there was a break!
One of the operators we handle has IFE on from PAX boarding until doors open the other end, on transfer from EXT to APU power NBPT ops normal and there is no rebooting of the IFE and no reports of problems on engine start.
If in doubt write it up, we are here for a reason, and yes it is a maintenance document.
Have done the occasional reset of the GAPCU, but not very oftem the system seems to work well a majority of the time.
Hope that helps