Investigating the glitches and the DAQ transmission problems of Sc_BS, using the RapidIO diagnostics data provided by its MCH, two DSP boards generating many errors were identified. One, connected to PSDi (serial #42084), was replaced yesterday morning, with a spare (serial #45261). The other, connected to the mirror, was a P5 board (serial #51181). This latter was replaced with a standard p4 board (serial #45257) with its output stage modified in order to have the same output resistance of a p5. In this way the gain was kept while the dynamics was reduced by only about 12 % (10 V / 28.5 Ohm = 0.35 mA vs 0.31 mA of maximum current erogation of AD8397 opamp). This morning the interferometer was successfully locked with this new setup.
SInce the BS board replacement, the DMS flag monitoring the TF from Sc_BS_MIR_Z_CORR to the coil current monitoring channels (V1:Sc_BS_MIR_VOUT_DL and DR, UL, UR) is red.
Indeed, the VIM plots show that there is no coherence anymore between them at 2012 Hz (figure 1, top right).
Figure 2 : looking at the channels with dataDisplay:
- purple: current situtation (ITF locked)
- blue: situation on 24 November
--> It looks like we now see only ADC noise, and that the four VOUT monitoring channels are not enabled/plugged?
