AT&T AUDIX Networking 585-300-903 - Manual (Page 129)

DCP Mode 2 Installation and Administration 11-11
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INSTALLING A 7400A IN A MODEM POOL
The 7400A Data Service Unit (DSU) can replace the MTDM in modem pooling applications on a System
75, System 85, DEFINITY Generic 1, Generic 2, or Generic 3. Instructions for installing a 7400A DSU in
the D-lead controlled (rack-mounted) modem pool instead of an MTDM are summarized in this section. To
install the 7400A in a stand-alone modem pool, see the next section, Installing Stand-Alone Modem Pools.
1. Disconnect the power cord, the line cord, and the RS-232 cable from the 7400A.
2. Open the top door of the 7400A by inserting the tip of a ball-point pen into the small hole near the
LINE label on the back panel. Push in on the tab on the hole while pulling up on that side of the
door. Repeat the procedure for the other side of the door. Lift off the door and set it aside.
3. Rotate the 7400A so that you are viewing it from the front. Look straight down at the inside and
locate the large silver arrow pointing toward the back of the set. The arrow points to the EIA
connector board. The board is perpendicular to the plane of the arrow. You can see it at the point of
the arrow.
4. Look at the EIA board from the front of the set. You should see DTE printed on the left hand corner
of the board. If you see DCE, pull the board up until it is completely free. Rotate it until you can
read DTE from the front of the 7400A and plug the board in again.
5. Close the door by hooking the hinges under the front housing and then snapping the rear tabs into
place.
6. Check the position of the slide switch located near the front of the access door opening. It should be
positioned to the left as viewed from the front of the unit (position B). This is the normal position for
operation in a modem pool. There are some 9600 bps modems which will not operate properly with
the switch in this position, particularly those modems employing data compression and error
correction (such as the Hayes SMARTMODEM 9600). For these modems, position the switch to the
right (position A).
7. Plug one end of the D8W-87 from the adapter harness into the labeled line (see step 13 for
information on the adapter harness).
8. Plug the power supply cord into the receptacle labeled POWER on the 7400A.
9. Plug one end of the EIA-232-D cable into the port labeled PORT 1 on the 7400A, and the other end
into the EIA port on the modem.
10. Make sure that your PBX is administered to support the 7400A in a modem pool arrangement. See
the 7400A Modem Pool Installation Guide (555-020-708).
11. Plug the power supply into an AC power outlet.
12. Use the front panel to set the 7400A options according to the following table. See the 7400A Data
Module User’s Manual (505-020-706) for details.