AT&T System 75, Wiring Diagram

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CHAPTER 2. HARDWARE (66/110-Type)
The 154A-type backboard consists of four 157B connecting blocks
factory-mounted on a blue backboard. This multiple arrangement
provides space to terminate eight 25-pair cables. The 154A-type
mounting is used in the equipment room in the distribution field.
66-TYPE CONNECTING BLOCKS ORDERING INFORMATION
Description Comcode
66M1-50 Connecting Block
101 238 178
157B Connecting Block
403 613 003
166-Type Backboard
403 612 922
154A-Type Backboard
403 612 997
183-Type Backboards
The 183-type backboard (Figure 2-14) provides mounting space for
66M1-50 connecting blocks. It is available in the four colors (blue,
green, purple, and yellow) that are used to identify the functional areas
in the cross-connect field. The 183A-type backboard mounts four
66M1-50 connecting blocks. The 183B-type backboard mounts eight
66M1-50 connecting blocks. The 183C-type backboard mounts two
66M1-50 connecting blocks. White backboards that are used for
connections between the main distribution field and satellite closets can
be obtained from outside vendors.
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