63MN024-010
TFAM
Case B
Fibre optic DL troubleshooting
(The following procedure is summarized by the fl ow-chart in Fig. 3.3.14c)
1. Check to see if there are any points in which fi bres are experiencing a short radius of
curvature. In these cases, rearrange the optical path in order to avoid sharp bends (if
necessary, replace the optical cable with a longer one). If the TFLN red LED switches off,
troubleshooting has been successfully carried out. Otherwise, follow the next steps.
2. Check to see if SC-APC connectors are properly installed at both fi bre ends. In case
they are not, replug
the SC-SPC connectors to adapters. If the TFLN red LED switches off,
troubleshooting has been successful. Otherwise, follow the next steps.
3. Disconnect the optical fi bre and clean it at both ends, then clean the SC-APC ports on
both the TFLN and the Remote Unit. Re-connect the fi bre to relevant ports after cleaning.
If it hasn’t made the TFLN red LED switch off, follow the next steps.
4. Disconnect the optical SC-APC connector from the Remote Unit’s DL port, and measure
the output power POUT(DL) at the corresponding fi bre end. Then, go to the TFLN side,
disconnect the optical SC-APC connector from the TFLN DL port and measure the input
power PIN(DL) coming out of the TFLN DL port. Calculate the DL fi bre attenuation ADL as
ADL [dB] = PIN(DL) – POUT(DL)
a. If ADL > 4dB, then there are problems with the fi bre optic cable. Replace it with a
new one.
b. If ADL < 4dB, the troubleshooting procedure has not identifi ed the problem. Refer
to the Supervision System or contact assistance.
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