Installation manual

9
The following customer-supplied equipment is required for the installation of a Model 3921Plus modem:
• A COMSPHERE 3000 Series Carrier.
• A 50-pin mass termination cable.
• One of the following modular or 50-pin leased or dial network interfaces:
— RJ11C for single line dial permissive applications
— RJ21X for multiple line dial permissive applications
— 66 punchdown block
• One Network Interface Module (NIM) for modems installed in Slots 1–8 and one NIM for modems
installed in Slots 9–16 (required for dial-line applications).
For installation of the COMSPHERE 3000 Series Carrier into a cabinet, refer to the COMSPHERE 3000 Series
Carrier, Installation Manual, Document No. 3000-A2-GA31.
Model 3920 Plus Input Voltage Requirements
The power supply used with the Model 3920Plus modem (Figure 3) is auto-sensing and capable of operating
(without reconfiguration) with input voltages from 100 Vac to 250 Vac, and input frequencies from 50 Hz to
60 Hz.
Model 3920 Plus Modem Installation
Before installing your standalone modem, make sure your installation site is clean and well-ventilated. Allow
space around the modem for installing cables and telephone cords, and make sure the modem is located within
reach of the ac power outlet. The distance between your modem and DTE should be minimized if DTE data rates
exceed 19,200 bps. Also, low capacitance cables may be necessary for speeds greater than 19,200 bps or distances
greater than 50 feet.
The rear panel of the Model 3920Plus modem (Figure 3) has the following switches and connectors:
• An ON/OFF power switch.
• An 8-pin DIN type power receptacle for the dc power supply.
• An 8-pin modular keyed jack (Lease) for 4-wire/2-wire leased lines.
• An 8-pin modular keyed jack (Dial) for backup lines (2-wire dial or 2-wire lease).
• A 4-pin modular jack for the Network Management System (NMS) connection.
• Four 25-pin DB-25-S receptacles for the DTE interfaces.