User Manual

AS4000 Operations and Maintenance

Section

605-0000-431

. Issue 1.6. Date3/2/99

DLP-006

Page 25 of 44 © Copyright Airspan Communications Corporation 1999

ALARM: RX LOSS OF SIGNAL

Alarm Indications

Sitespan:

Rack: Major/Prompt

Modem Shelf Alarm Panel: Fault Alarm

Card Alarm: RX loss of Signal

Probable Cause

a) Wrong TX/RX connection

b) Broken 2Mbit/s cable

c) Exchange problem

Consequences

1) Service failure to all subscribers connected to the modem shelf.

2) The call in progress LEDs on the CT modems will be off irrespective of the call state.

Maintenance Clear Strategy

STEP PROCEDURE

Observe full ESD precautions.

1. Press Receive Attention on the modem shelf cover to suppress alarm.

2. If digital tester available check the 2Mbit/s TX out at the Digital Distribution Frame

(DDF). If the signal is not present the fault is in the exchange/ backhaul.

3. Use a digital tester to check the RX 2Mbit/s at test point on the front of the TU Card.

4. If 2Mbit/s is not detected at the TU card inspect coax connections to the DDF and

backplane. Check the cable for open / short circuits etc. Replace faulty cable /

connections.

5. If 2Mbit/s is detected at the TU card but RX 2Mbit/s Fail alarm still indicated change TU

card.

6. Before inserting the Tributary Unit check that the DIL switch settings. The Tributary unit

DIL switches should be set as in 1. and should be the same as the card being replaced.