Perfom "inloop" Port 4 on PQ1 in slot 2 of OSN3500 by T2000 software and connect with NG-SDH Analyzer (ANT20SE) to check E1 signal. The alarm on ANT20SE is LOS.
The alarm LOS occur on port 4 of PQ1 card in slot 2 (OSN-3500-2-N2PQ1-4) and the "service lamp" on PQ1 is red.
- Perform manual switching by T2000 software (from slot 2 to slot 1), the alarm "LOS" on ANT20SE doesn't clear.
- Replace the D12S in slot 19 by the new D12S card, the alarm "LOS" on ANT20SE still occur.
- Check the connector DB44 on E1 cable, I see that the pin 12 is bent, so use the clip to turn this pin straightly, the alarm "LOS" on ANT20SE is cleared.
May be the PQ1 card or D12S card is fault
May be the E1 (120) cable or connector is fault
- Check all the possible causes: card, connector, cable... and test each case until find the reason and have the solution to fix.