GE11-P-12L1: Broken DAC circuit on VFAT22

It was noticed during performance analyses that the S-bit rate for VFAT22 was always empty. More specially, the rate was always recorded to be at 0 Hz, regardless of the THR_ARM_DAC. Additionally, S-curves are empty and the calibration pulse scan reports all channels as dead.

Deeper investigations showed that the DAC circuits for VFAT21 appear broken.

Considering the poor/null performances of that VFAT, it could (should?) be masked from the data taking (i.e. set the GBT phase at 15).

Plots to follow...