Chapter 3 - Troubleshooting; General; All Leds Are "Off; Alarm Led - TC Communications TC2400 User Manual

Rack mount/stand alone hi-speed multi-drop (ring) fiber optic modem

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Table Of Contents

Table of Contents

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.

These are the reference values we use to calculate the loss on the fiber:

Multimode 850nm

Multimode 1300nm

Single Mode 1300nm

Single Mode 1550nm

*These numbers are listed for reference only. We recommend an OTDR reading be used to determine actual link loss.