AT&T 75 Wiring Manual page 365

Voice Terminal Installation
1 5 . If ground start must be provided, do steps 16 through 23 to install ground start
switch; otherwise, go to step 24.
1 6 . Remove cover from 551A key.
1 7 . Remove housing from 500- or 2500-type voice terminal.
1 8 . Run and connect wire from red lead (R) on voice terminal through 551A key to
yellow and/or black lead on voice terminal.
1 9 . Mount base of 551A key to 77A bracket using screws provided with bracket.
2 0 . Replace cover on 551A key.
2 1 . Place groove in bracket over lip of voice terminal set base (see Figure 3-112).
2 2 . Replace voice terminal housing.
2 3 . Repeat steps 16 through 22, as required.
2 4 . Connect voice terminals to the information outlets.
2 5 . Install patch cords or jumper wires between the switch side and the station side of
the Station Distribution Field.
Installation—Optional DID Make-Busy Trunk
1 . Run and connect jumper from one DID make-busy lead to TK terminal (first
appearance) on the yellow emergency transfer row (see Figure 3-109).
2. Run and connect jumper the other DID make-busy circuit lead to ST terminal
(first appearance) on the yellow emergency transfer row.
Figure 3-109. Connections at Trunk/Auxiliary Field for Optional DID Make-
Busy Trunk—Z1A Emergency Transfer Unit
110-TYPE HARDWARE
3-149