DEFINITY Made Easy Tools
Issue 3, December 2001

Add Channel Service Units

Installing the 120A CSU

120A Channel Service Unit Module shows the connection points.

1. Unplug the DS1 circuit pack from its slot.


2. Install a 4C retainer in the 50-pin plug associated with the DS1 circuit pack slot.


3. Plug the 25-pair connector on the 120A directly into the plug associated with the DS1 circuit pack slot.


4. Secure the 4C retainer around the 120A.


5. Attach the supplied H700-383 cable to the 120A and to the 700A loopback jack.



This cable is directional. To determine the end that connects to the 120A, perform a continuity test between pins 3 and 7. The end with this continuity is the 120A end. The shield is grounded only at the 120A end.

Use the cable provided. If using cabling other than that provided with the 120A, see H700-383-Equivalent Cable Guidelines.

6. If using external alarm equipment, attach the supplied DW8 cable to the 120A and the external equipment. The maximum length of this cable depends on the alarm equipment.


7. If a TN464F is used, make sure the circuit pack is set for 24-channel operation. Set the switch on the circuit pack.


8. From the DS1 circuit-pack form of the system administration console, set the line compensation field to 0-133 feet (40.6 m).


9. Reset the 120A by reseating the DS1 circuit pack.



When you reinsert the DS1 circuit pack after installing a 120A CSU the 120A resets. The DS1 circuit pack initializes and tests the 120A. When initialization and testing is complete, the green LED goes off. If the RED indicator is OFF after the test, the ICSU is working.

10. If the circuits do not pass the self test, troubleshoot the 120A as instructed in Integrated CSU Module Installation and Operation.

H700-383 Cable Pin Assignments provides the H700-383 cable pinouts. H700-383 Cable Lengths by Group Number provides the cable lengths for each cable group number.

120A Channel Service Unit Module

Figure Notes:

1. Rear of carrier containing DS1 circuit pack


2. 120A CSU


3. 4-pair cord to network interface (H700-383)


4. DW8A-DE 4-pair cord to alarm contacts (optional)


5. To 25-pair connector on rear of carrier containing DS1 circuit pack