3Com 3CNJPSE24 - Manual (Page 31)

Appendix C — Troubleshooting
Ethernet Power Supply User s Guide C-3
Problem Resolution
The "Port LED
on one port is
not lit and the
corresponding
end device does
not operate. The Ethernet Power Supply did not detect
a connected end device and therefore the
port is not providing power. Verify that:
• The end device is Power Over LAN
enabled.
• You are using a standard UTP Category
5 cable, including all 8 wires (4 pairs).
• If an external splitter is in use, replace
it with a new splitter. Discard the
faulty splitter.
• You are not using a crossover twisted
pair wire.
• The end device is connected to the
Data & Power port (upper RJ-45
connector).
In addition, try to:
• Re-connect the same end device into
a different port on the same unit. If it
works, there is probably a faulty port
or RJ-45 connection.
• Bypass the long twisted pair cable
and bring the end device close to the
Ethernet Power Supply and connect
to one of the ports using a short
cable. If this works, there is probably
a faulty connection or short on the
long cable, or one bad RJ-45
connection along the line.
Connect the end device into a different
Ethernet Power Supply. If this works, the
Ethernet Power Supply is probably faulty.
Try to power it up again and verify a
correct power-up LED sequence.