Installation manual

14
Model 3921 Plus Modem Installation
CAUTION
If the Model 3921 Plus is removed from the carrier, always use a
ground strap when handling the modem. Always store the
Model 3921
Plus in an antistatic bag when it is removed from
the carrier.
The Model 3921Plus is designed for installation in a COMSPHERE 3000 Series Carrier which supplies both the
operating power and the leased and/or dial network connections. For additional information about the
COMSPHERE 3000 Series Carrier, refer to the COMSPHERE 3000 Series Carrier, Installation Manual,
Document No. 3000-A2-GA31.
The COMSPHERE 3000 Series Carrier has 17 slots which can hold up to 8 Model 3921Plus modems and one
shared diagnostic unit (SDU). The SDU is required when the modems in the carrier are controlled by an NMS, or
when multiple carriers in a cabinet configuration are to be controlled by a single shared diagnostic control panel
(SDCP). The SDCP of the COMSPHERE 3000 Series Carrier is the user interface to the Model 3921Plus modem.
A single SDCP can control up to eight carriers.
The installation of a Model 3921Plus varies slightly if an SDCP is installed on the front of the carrier. To install a
Model 3921Plus modem into the carrier without an SDCP, perform the following steps:
1. At the rear of the carrier, install the rear connector plates. Make sure the plates use the same slot position
as that intended for the modem.
Loosely fasten the plates. This allows for slight adjustments later when installing the modem.
2. At the front of the carrier, hold the modem vertically, with the latch on its faceplate in the open position,
and insert it into the top and bottom card guides of one of the odd slots numbered 1–15 (Figure 4).
Slide the modem into the slot, aligning the modem with the rear connector plates, until the backplane
connector and DTE connector seat firmly into the back of the carrier. The faceplate latch automatically
closes as you push the modem into the carrier. To lock the modem into the carrier, press the faceplate latch
until a “click” is heard.
3. If the carrier is ON, the Power LED on the faceplate of the 3921Plus lights. After several seconds the
modem completes its power-up self-test, in which all faceplate LEDs light.
Return to the rear of the carrier and tighten the rear connector plates.