AT&T System 75, Wiring Diagram

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CHAPTER 5. AUXILIARY EQUIPMENT INSTALLATION
The voice pair that connects to a TN742 or TN769 analog line circuit
pack port occupies the first pair of the information outlet. The ISN data
pairs occupy the second and third pairs of the information outlet. The
voice and data pairs can be separated as shown in Figure 5-18. The
data pairs either connect to an Asynchronous Interface Module (AIM)
located in an ISN concentrator or the ISN packet controller.
The Z3A1 ADU is equipped with two 8-pin modular jacks to terminate
the line cords from the information outlet and an analog telephone.
Normally, this ADU is powered from the connected data terminal. The
ADU can also be remotely or locally powered using a 2012D transformer
equipped with a 248B adapter. ADUs connected to receive-only printers
always require external power. The need for external power must be
determined experimentally for ADUs connected to other devices. For
details on ADU installation, refer to the Z3A Asynchronous Data Unit
User’s Manual (555-401-701).
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