aLIGO LHO Logbook

H1 CDS (ISC, SUS)

filiberto.clara@LIGO.ORG - posted 12:10, Wednesday 04 October 2017 - last comment - 15:26, Wednesday 04 October 2017(38887)

SUS RM1 and RM2

Issues reported with some of the volt monitor readbacks for RM1 and RM2, alog 38883. The tip-tilt coil drivers were pulled out and the output buffer IC's OP27 (IC5) were replaced.

S1200608, IC5 replaced on all channels.
S1200609, IC replace on CH2,CH3, and CH4.

Comments related to this report

jeffrey.kissel@LIGO.ORG - 13:36, Wednesday 04 October 2017 (38889)ISC, SUS

Link

J. Kissel, F. Clara

Put in offsets that the COILOUTF to double check whether the VOLTMONs were functional. 
Didn't see a reaction out of the VOLTMONs on the MEDM screen. 
Went out to CER with Fil.
Double checked that the VOLTMONs were functional by inserting 0.5 [V] into each coil driver's DAC input with an independent voltage supply, and saw reaction in VOLTMONs on MEDM screen.
Now suspicious of the AI / DAC chain, Fil inspected the pins (which were clear) then reseated / better seated the DAC SCSI cable at the back of the IO chassis.
Functionality restored: offsets in the COILOUTF make the VOLTMONs light up.

So, apparently the damping loops I'd turned on yesterday weren't doing anything. 

Turned on the damping loops and they now appear unstable, will investigate further.

jeffrey.kissel@LIGO.ORG - 15:26, Wednesday 04 October 2017 (38894)

Link

Resolution of problem described in LHO aLOG 38893.