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I am now looking for where to hook up the power supply. From what I read it is on the terminal block to the right? That one has a connector on a relatively short cable wired to the wire block. One of the connector leads goes to a lug on the metal frame (ground?) Does the connector plug into a power supply? if so which one? Thanks.
The power supply connections are not normally connectorized. The power connections appear on a terminal strip at the base and are shown on the SD. Do you have SD-66520-01? It should be in the TCI library.
Page G2 Fig. 54 shows battery and ground terminations on the MISC. terminal strip:
BAT = term's 1, 2, 3 & 4
GRD = term's 45, 46, 47 & 48
+/- RINGING = term 22
RINGING GRD = term 24
However there are some strapping options on this terminal strip so without knowing what's there it's impossible to say with certainty that it will work with just these connections.
There is an 8 pin Cinch-Jones plug like the one in your photo except chassis mounted, on the back of the 555 TEL unit and a 10 pin one on the front used to connect the dial lead connections from the terminal block under the dial mounting, and the headset jack leads, to the TEL unit.
BSP 536-550-210 para. 3.07 forward discusses grouping of multiple positions. The 8 pin plug on the back of the TEL unit is for that. That might explain your cable if it ended in a socket rather than plug but so far I don't see anything about a plug ended cable.
However regardless of that, the gender of your mystery plug is wrong to plug onto the TEL unit and I can't see from your photo where the other end of the cable terminating in the 8 contact plug goes. Where does it go? It seems unlikely someone would have connectorized the power with a C-J plug since that would require soldering the plug terminals in the field. I'd expect a 25 pair cable to be used with multiple pairs paralleled to reduce feeder resistance.
If you need assistance interpreting SD-66520-01 just say so.