- 15 -
TC2400 & TC2401
Ring User's Manual
Rev. 1.7
Chapter 3 - Troubleshooting
*These numbers are listed for reference only. We recommend an OTDR reading be used to determine actual link loss.
These are the reference values we use to calculate the loss on the fiber:
Multimode 850nm
:
3 dB loss per km on 62.5/125 µm cable*
Multimode 1300nm
:
2 dB loss per km on 62.5/125 µm cable*
Single Mode 1300nm
:
0.5 dB loss per km on 9/125 µm cable*
Single Mode 1550nm
:
0.25 dB loss per km on 9/125 µm cable*
General
Alarm conditions occur whenever an optical problem or "fault" is detected by the TC2400/2401. Under
normal operation, all LEDs should be "On" (solid or blinking).
All LEDs are "Off"
If no LEDs are lit on the unit, check the DC power supply, terminal block connector plug, and/or power
source.
Optic Cable Types
Conventionally, fiber optic cable with yellow-colored insulation is used for single mode applications; gray or
orange-colored insulated cable is for multimode use. If multimode cable is used in a single mode application,
the test results could be erroneous and confusing.
Calculating the Loss on the Fiber
The fiber optic link and/or the connectors are frequently the source of communication problems. If problems
are present, check the optic connectors and the integrity of the link first. Ideally, the link should be calibrated
for total loss after the installation has been completed. This will accomplish two things: (1) it will verify that
the total loss of the link is within the loss budget of the device and (2) it will provide a benchmark for future
testing. For example, a system that has been tested as having 6dB of signal loss when installed should not
suddenly test out as having a loss of 10dB. If this were the case, however, the fiber link or connector would
probably be the source of the problem.
