J. Oberling, T. Shaffer, R. McCarthy, M. Pirello, A. Jennings

At approximately 8:56 UTC (1:56 PDT), the ISS first loop failed, causing a lockloss a few seconds later.  Tony called me shortly after 7:00am PDT, and I logged in remotely to take a look.  All ISS signals were reading incorrectly (ISS PDA and PDB were both reading <1V, AOM drive voltage was reading negative, ISS QPD very noisy; see attached trend), but we still had a running laser and a locked and operating PMC and FSS RefCav.  This is important to note as if we had lost any DC power (like one would first suspect upon seeing both PDs and the QPD "fail" at the same time) we would also not have an operating laser, a PMC, or a RefCav (the PMC/RefCav locking servos and PSL control box in the PSL LVEA rack all pull from the same +/-24V and +/-18V DC supplies, so losing one would take out all items connected to that supply; PSL CER rack uses a different +/-18V DC power supply).  Suspecting a failed AA chassis, since everything ISS-related was down, I drove to the site and upon arriving, sure enough, TJ and I found the ISS AA chassis was reporting no -15V.  Richard and I pulled the chassis and he found the -18V wire running from the ON/OFF rocker switch to the voltage regulator board (which takes the +/-18V to +/-15V) was very loose (it fell out of the crimp connector upon being touched).  Marc re-crimped the wire with a new connector and powered up the chassis; everything came up as expected.  We then installed it, and lo and behold we have ISS signals that make sense.  I walked Austin through re-engaging the ISS and everything came back to their normal operating points.  With the ISS now working correctly, Austin has begun relocking the IFO; at the time of this writing they are at "Find IR."

Serial number for this AA chassis is S1001249.

Edit to add: Clarification of +/-24V mention only applying to PSL rack items, not CER; added serial number of PSL ISS AA chassis.