The power pin outs are the same for all LTN-72s and LTN-92 INUS
115VAC 400hz (Primary Power) 5 amps
High - J1B Pin 1
Common - J1B Pin 2
115Vac 400Hz (Heater Power) 10 amps
High - J1B Pin 3
Common - J1B Pin 4
J1B Pin 5 is chassis ground. This is connected to the aircraft frame / INU tray
Battery (+28VDC)
+28VDC - J2B Pins 3 and 4
-28VDC - J2A Pins 3 and 4 (this is battery return)
No other power is required to run the INU. All other voltages are created by the INU and fed throughout the unit.
Your assumptions on the plug layout are correct. A is top and B is bottom.
