Since the SOA troubleshooting we had lost some IR power and we were not able to close the PSTAB.

This morning we continued the investigations starting with the fiber connections on the telecom rack in DAQ room (starting from 10h15 LT, no improvement).

Then we went at the WEB and checked the fiber connections (we cleaned some, with no improvement). 

By measuring the powers we realized that the problem was due to the fibered splitter after the AOM. It was sufficient to move it to recover the expected power.

We were then able to close the PSTAB loop, starting from 12h UTC (SOA setpoint 64mA).

Measured powers: 3 mW at the input of the ALS box, 2.6mW at the input of the SOA (after fibered polarizer), 4.3mW (60mA SOA), 2mW (slighlty more) after AOM (60mA SOA) and around 2mW at the output of the 90:10 splitter (=input ampli 2W).