Our new (circa late 1960's) house has a NuTone intercom system that needs to
go. Some of the functions work, but for the most part, the system is dead.

After removing the face plate from the main control box, I found a label
that indicated that the system runs off of a 30V AC transformer (the label
says the transformer is "located elsewhere"). After crawling through a
large portion of the house, I still have not found "elsewhere".

Where to begin? My first (possibly biggest) problem is that the "hot" wire
isn't apparent...

Suggestions?

KB