filiberto.clara@LIGO.ORG - posted 14:41, Tuesday 16 August 2016 - last comment - 15:32, Thursday 18 August 2016(29135)
PEM Power Supplies
PEM power supplies in the CER mezzanine were swapped out for Kepco model JQE supplies. This model is a 1/4 rack version, and allows for four power supplies to be mounted on one shelf. This is to make room for the ±24V power supplies that will be used to power Beckhoff/Baffle PD Amplifier/ Spool X/Y camera ect. All PEM instrumentation microphones, magnotometers, ect. were powered down from around 10:30 am to 1:00 pm. All power is now restored.
Fil, Terra
I did a quick check of power spectra for all corner station mics and mags, before and after power supply swap. Attached spectra show pre-swap in darker colors as references, post-swap in lighter.
Found post-swap saturation in several mags, strongest in MAG_LVEA_INPUTOPTICS (first attachment at 21:03 UTC ). Fil switched this mag to battery power, which has temporarily fixed the problem (second attachment at 23:03 UTC). He took a look at the mag box in the lab but found nothing wrong. We left it battery powered for now. Will investigate more tomorrow.
Additionally, it looks like MIC_LVEA_HAM7 got disconnected around 23:03 UTC (top right of second attachment).
Channel 2 of AA Chassis S1300104 found to be bad.
MIC_LVEA_HAM7 started negatively railing yesterday ~3 hours after the power supply swap, trend attached (first drop then raise is from power supply swap). Turns out that AA channel has gone bad (bottom most AA chassis in PEM rack). Fil will pull it and have a look tomorrow morning.
AA chassis repaired, HAM7 mic back up and running. MAG_LVEA_INPUTOPTICS was also fixed. At this point, all corner station mics and mags are running well. Attached are power spectra for all.