Instruction manual

HARDWARE DESCRIPTION
Circuit Pack Compatibility
The following System 75 CPs can be used in System 25, if required:
● The TN742 and TN746B Analog Line circuit packs can be used instead of the ZTN78 Tip
Ring CP. The TN742 and TN746B support bridged stations and out-of-building or Off
Premises Stations (OPS), the ZTN78 does not. The TN746B will only function properly in
R3V3 systems.
● The TN762B Hybrid Line (Version 4 or later) can be used instead of the ZTN79.
● The TN747 CO Trunk can be used instead of the ZTN76 (Ground Start Trunk) or the
ZTN77 (Loop Start Trunk).
Circuit Pack Features
All system CPs have the following features:
● Solid-state circuitry mounted on 7.7 by 14.1-inch printed wiring board (TN-type)
● Color coded faceplate labels identify the CP type and function (White = Control, Purple =
Port or System Resource)
● Individual circuit functions all contained on one CP
● Metal tab for grounding
● Locking tab-type handle provides easy insertion or removal of a CP
● Port CPs can be inserted or removed with power “On” and the system processing calls.
Only the calls utilizing circuits on a removed CP will be affected.
Note: Power must be turned off when replacing the CPU/MEM or Service Circuit.
● Status LEDs
— Port CPs:
Red—“On” several seconds during power up and test, “Off” with test pass. After test
pass, “On” if fault in CP is subsequently detected.
Green—“On” indicates resource available (port is translated).
Yellow—“On” indicates a call in progress. “Off” when not in use.
All LEDs “Off”—CP is not translated.
November 1995
4-13