Chapter 3 - Troubleshooting; General; All Leds Are Off; Alarm Led - TC Communications TC1630R User Manual

Rack mount/stand alone t1/e1 fiber optic modem

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Table Of Contents

Table of Contents

General

Alarm conditions occur whenever an optical problem or "fault" condition is detected by the TC1630.

All LEDs are Off

If no LEDs are lit on the unit, check the DC power supply, terminal block connector plug, change to alternate

power jack on the rear panel, fuses A and/or B indicated on page 17, and/or the power source. If the problem

persists, contact the Technical Support Department at TC Communications, Inc.

Alarm LED

When an alarm condition is detected, the Alarm LED will flash. The following fault conditions will cause

the alarm to be triggered:

1. Optic signal lost from optic "Rx."

2. Optic signal is marginal, which causes invalid data packets to be received; the "SYNC" LED will be "Off."

3. Received "space" or "mark" from local T1/E1 device.

4. An invalid Line Code setting exists.

5. The Line Length setting does not match the Line Code.

6. The local or remote T1/E1 signal is lost; the "LLOS" or "RLOS" LED will be also be flashing.

Note: The "RLOS" LED will be Off when there is no fiber cable connected or the fiber cable is bad.

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 connectors are frequently the source of various problems. Check out the

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 total loss when installed and suddenly tests out as having a loss

of 10dB probably has a connector or link problem.

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

Multimode 850nm

Multimode 1310nm

Single Mode 1310nm

Single Mode 1550nm

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