3Com 3C17708-US - Switch 4050 Getting Started Manual page 59

connecting a working power cord to the 'problem' device
testing the PSU in the spare slot or another unit
installing and testing a second PSU in the 'problem' slot
If the LED lights flashing red the PSU has shutdown due to over-heating.
See Solving Hardware Problems
The Temperature LED lights flashing red
The Switch unit has exceeded its operating temperature and may
shutdown. See Solving Hardware Problems
The Fan LED lights red
One or both of the fans have failed and have stopped or lost speed. See
Solving Hardware Problems
A link is connected and yet the Port Status LED for the port does
not light
Check that:
The Switch and the device at the other end of the link (or cable) are
connected securely.
The devices at both ends of the link are powered-up
The quality of cable is satisfactory
Auto-negotiation settings are the same at both ends.
Link problems will occur with 10BASE-T or 100BASE-T where
auto-negotiation is disabled and incorrect cables are being used.
Link problems will occur with fiber if:
The Receiver (RX) and Transceiver (TX) cable connectors are
swapped
Fibers are broken
Auto-negotiation differs at either end (a link appears at the 'fixed'
end and not at the auto-negotiation end)
Solving Problems Indicated by LEDs
on page 60 for more advice.
on page 60
on page 60 for more advice.
59
for more advice.