CHAPTER 6: Testing and Diagnostics
39
6.2 Troubleshooting
If a problem occurs, check the displayed indications and refer to Table 4-1 in
Chapter 4
.
Identify the trouble symptoms and perform the actions listed under Corrective Measure in the order given until
the problem is corrected.
Problem:
The mux is “dead.”
Probable Cause #1:
No power.
Corrective Measure #1:
Check that both ends of the power cable are properly connected.
Probable Cause #2:
Blown fuse.
Corrective Measure #2:
Disconnect the power from both ends and replace the fuse with another fuse of the
same rating.
Probable Cause #3:
Defective unit.
Corrective Measure #3:
Replace the mux.
Problem:
One of the POWER indicators lights in red.
Probable Cause:
Defective power supply.
Corrective Measure:
Turn the respective power supply off for at least 10 minutes, then turn it ON again. If the
POWER indicator is still red, have the mux repaired as soon as possible.
Problem:
The SYNC LOSS indicator of the fiber optic link lights.
Probable Cause:
External problem.
Corrective Measure:
Activate the local loopback on the mux. Check that the SYNC LOSS and AIS indicators of
the fiber optic link in use turn OFF. If the indicators turn OFF, check the fiber optic interface connections, the
fiber optic transmission path to the remote unit, and the remote unit.
Problem:
The AIS indicator of the fiber optic link lights.
Probable Cause #1:
External problem.
Corrective Measure #1:
The remote equipment connected to the mux’s fiber optic link of the mux sends an
AIS sequence. Check the remote equipment.
Probable Cause #2:
Defective mux.
Corrective Measure #2:
Activate the local loopback on the mux. Check that the SYNC LOSS and AIS indicators
of the fiber optic link in use turn OFF. If one of the indicators remains lit, replace the mux.
Problem:
None of the units connected to a local mux receive the remote equipment.
Probable Cause #1:
External problem.
Corrective Measure #1:
Activate the local loopback on the mux. Check that all the SYNC LOSS and AIS
indicators turn OFF and that the equipment connected to the local channels receive their own transmissions. If
the indicators turn OFF, the problem is external. Troubleshoot the remote unit and the fiber optic transmission
path.
Probable Cause #2:
Defective mux.
Corrective Measure #2:
Replace the mux.