User's Manual Part 2

6-10 Common Problems, Troubleshooting, and Frequently Asked Questions
4
Power is not being delivered to the RAU.
• Switch the UTP cable to a different Expansion Hub port to see if the same
problem occurs.
If the LEDs on the new port are both green, there is a problem with the
Expansion Hub.
If the problem persists, there is a problem with either the RAU or the UTP/
STP cable.
• Check that the UTP/STP cable has been properly crimped and passes a
standard TIA/EIA 568-A CAT 5 compliance test.
If the cable passes the CAT 5 test, replace the RAU.
5
RAU has lost synchronization.
• Make sure that the UTP/STP passes CAT 5 testing.
• If the cable is OK, replace the RAU.
6
The Expansion Hub is not properly receiving the synchronization signal from
the Main Hub.
• The MMF cable connection might not be good or if system was working,
the MMF downlink cable is pulled out or cut. Switch MMF cables.
• If the problem persists, switch to a different Main Hub port. If this solves
the problem, the Main Hub port is malfunctioning.
• If the problem persists, there is an Expansion Hub problem.
• If switching MMF cables is not practical, switch the uplink and downlink
pairs. (A connection error may have been made when connecting the Main
Hub
UP
port to the Expansion Hub
UP
port, and similarly for the
DOWN
ports.)
• If the Expansion Hub
SYNC
LED turns green, one of the MMF cables was
bad or the connection between the Main Hub and Expansion Hub was done
incorrectly. If both are bad, this test will not help. Switch to a different
Main Hub port.
7
The Expansion Hub is not properly receiving the synchronization signal from
the Main Hub.
Too much loss on downlink MMF. Might be due to MMF pairs not attached to
the proper connector.
• Check that the “
down
” cable end is in the
DOWN
port connector on both the
Main Hub and on the Expansion Hub. Same for the “
up
” cable end and
connectors for the
UP
port.
• If the problem persists, check the integrity of MMF cable using an Optical
Time Domain Reflectometer. If the fiber is faulty, replace it.
• If the MMF cable is OK, try using a different Main Hub port.