AT&T MERLIN LEGEND Installation & Maintenance Manual page 500

Maintenance and Troubleshooting
Channel Service Unit Loopback Test. Before you select the
channel service unit (CSU) Ioopback test from the Slot screen,
you must do the following:
1. Plug one end of a bantam-to-bantam patch cord (or a
Ioopback fixture, if one is available) into the EQ OUT jack on
the front of the CSU.
This causes the CSU to either loop back the network signal or
send the all-ones pattern, depending on the chosen CSU
option.
Plug the other end of the patch cord into the EQ IN jack on
2.
the CSU.
3. Using the maintenance screens, busy out the 100D module
(see "Line/Trunk or Station Busy-Out" later in this chapter).
Select "CSU-lpbk" from the 100D module Slot screen to start the
100D module to test data looping through the CSU. (Four tests
are run for each channel.) The following screen appears.
CSU-lpbk Slot
CSU-lpbk in Progress
Exit
CSU-lpbk Slot
CSU-lpbk Passed
Exit
5-22 Maintenance
This screen indicates that
XX:
the Ioopback test is
running.
This screen appears if the
XX:
Ioopback test is
successfully completed.