Hello,
do you mean the external power supply ? Or do you mean the generator switches ? they are both online and all lights at the Annunciator Panel are off, except "Autopilot Disengaged".
I did the procedure according to "Manual2.pdf" page 5.
1. ext pwr on
2. engine start switches > engine ist starting up
3. check generator 1 and 2 are on > all instuments come alive
4. ext pwr off


Did not find anything like "electric power supply".....did I really missed something ?

Greetings Sven