filiberto.clara@LIGO.ORG - posted 16:26, Friday 21 July 2017 - last comment - 11:05, Tuesday 10 July 2018(37694)
BS M2 FastIMON UR
aLOG 37666
Looked at the BS UR signal as reported by Jenne. Disconnected noise monitor outputs of coil driver and shorted the inputs to the AA chassis. From here we could see that UR has ~10dB gain difference than the other channels. Power cycled both the AA and coil driver, transfer function showed no change. Coil driver S1000355 in SUS-C6 slot U26 was replaced with S1100039. Transfer function for all signal outputs the same.
F. Clara, J. Driggers, R. McCarthy
It was determined that the last interface stages of the driver section for CPB/CBN(Fast Current +/-) that feed the Monitor board weren't able to drive the downstream circuits. ICs 9&10 were replaced and the issue with the channel was resolved.