Symptom
At an OptiX BWS 1600G station, a fiber connector on the RPC board is damaged and the fiber jumper must be replaced. After the fiber jumper is replaced, the receive optical power on the WDM side is low (-53 dBm).
The connected OAU board at the downstream station reports MUT_LOS and R_LOS alarms.
Cause analysis
After a detailed check, it is found that:
- The transmit optical power of the FIU board at the downstream station is within the permitted range.
- The receive optical power of the ODF connected to the local station is within the permitted range. That is, the line attenuation is within the permitted range.
- The receive optical power of the OAU at the local station is low.
- The receive optical power at the IN port on the FIU board at the local station is low.
- The fiber jumper between the IN port on the FIU board and the SYS port on the RPC board is normal.
The preceding information shows that the fault is located between the ODF and the FIU board. Possible causes of the problem are as follows:
- The fiber jumper between the ODF and the RPC board is damaged.
- The RPC board is malfunctioning.
Procedure
- Check the fiber jumper between the ODF and the RPC board. The fiber jumper uses an FC/PC connector at one end and an LHS/UPC connector at the other end, while the LINE port connector on the RPC is LSH/APC. The end faces of the FC/PC and LSH/UPC connectors of the fiber jumper is flat while the end face of the LSH/APC connector is tilted. Therefore, air exists between the LINE port on the RPC board and the fiber jumper connector. As a result, the transmit optical power of the pump laser on the RPC board is abnormal and the receive optical power on the WDM side is low. Change connectors of the fiber jumper on the RPC board so that the fiber jumper uses an FC/PC connector at one end and an LSH/APC connector at the other end. Then, the system operates properly.
