Coaxial Cable Subsystem - Cisco CVA122 Hardware Installation Manual

Chapter 4 Troubleshooting

Coaxial Cable Subsystem

For proper operation the Cisco CVA122/CVA122E Cable Voice Adapter must be able to establish a
connection with the service provider's CMTS. There are many conditions inherent to coaxial cable that
can inhibit this connection:
Verify the cable connection from the cable voice adapter to the HFC plant and headend by checking the
Step 1
video reception. You should test the same coaxial cable that the cable voice adapter is connected to—if
necessary, disconnect the cable voice adapter from the coaxial cable and connect a cable-ready TV in
its place.
If the TV does not receive any cable channels, contact the service provider to re-establish service to the
site. If the TV does receive cable channels, it indicates that the basic infrastructure between the site and
the HFC plant and headend is working; however, because data connections are much more sensitive to
signal interference than cable TV service, it is still possible that a problem exists that prevents reception
of the data signals.
If you are using a splitter or couple to share the coaxial cable between a TV and the cable voice adapter,
Step 2
remove the splitter/coupler, TV, and any other devices connected to the cable (such as video or DVD
players) so that the cable voice adapter connects directly to the coaxial cable coming out of the CATV
wall outlet. Make sure the cable voice adapter is the only device on this segment of cable.
If the cable voice adapter functions in this configuration, inspect the splitter and any other devices that
were installed on this cable segment. If necessary, upgrade them and their interconnecting cables with
ones that have higher-quality connectors—see "Coaxial Connector and Cable Specifications" in
Appendix B, "Connector and Cable Specifications" for the recommended cable and connector quality.
A high-pass filter might be necessary between the modem and TV to prevent signal interference. If this
does not help, you might need to install a separate cable for TV reception.
Disconnect the coaxial cable from the back of the cable voice adapter and inspect the cable and its
Step 3
connector. Is the center conductor on the coaxial cable end straight and of the correct length to ensure
a good connection?
If the center conductor is not straight or appears to be too long or too short, cut the coaxial cable behind
the connector end, and strip the insulation back. Make sure that the newly exposed center conductor is
straight. Before replacing the new cable connector end, check the general condition of the cable. Make
sure the new conductor end is securely crimped to the cable.
The center connector should extend 1/8 inch (3.2 mm) beyond the end of the connector.
Note
Is the coaxial cable running to the cable voice adapter in excellent condition?
Step 4
The coaxial cable between the cable voice adapter and the cable tap must be very high quality. The cable
insulation must be at least 80% braid with foil. If the existing cable appears to be of lesser quality or in
poor condition, replace the cable from the ground block or tap to the cable end.
Is the coaxial cable connection to the back of the cable voice adapter secure?
Step 5
Check that the coaxial cable end is securely screwed onto the F-connector at the back of the cable voice
adapter. Hand-tighten the connector, making sure it is finger tight; then give it a 1/6 turn.
OL-0799-02 (05/2001)
Cisco CVA122/CVA122E Hardware Installation Guide
Troubleshooting Subsystems
4-7