Where are you located? It might be easier to help if one of us is
close enough to travel to you.
The switchboard uses a 20B2 Power Unit, or equivalent key system power
supply. That is the Western Electric model number. The switchboard
itself is simple to power up. Although it has been quite a number of
years since I have worked on one, I believe that there are terminals
in the rear that are labelled BATT ,GRD, GEN, GEN GRD. BATT gets -24
VDC filtered battery, GEN gets 90V @30 Hz for ringing.
The trunks and stations are also labelled, or they are terminated on a
50-pair cable that is probably cut off on the board that you have. If
you call me at
631-749-0100 (anytime) we can determine what you have,
what you need, and whether I have a power supply for you.
Arthur P. Bloom, Curator,
Shelter Island Telephone Company Museum
PSTN
631-749-0100
CNet 749-0100