corey.gray@LIGO.ORG - posted 07:21, Tuesday 08 August 2023 - last comment - 08:17, Tuesday 08 August 2023(72054)
H1 Lockloss and ALS-X PLL Issues
H1 went down at 1327utc (627amPT), and it definitely had ALSX issues---ALS_XARM guardian node was in a FAULT state.
The camera flashes & ALS x Transmitted channel looked noisy.
Tried a few items on the PLL / ALS_CUST_LASER_LOCKING.adl screen, but none made any changes for the better. What I tried:
- taking beatnote RF min from -10 to -15 (and other values)
- took crystal frequency to -200 (and other values)
- Toggle the Force & No Force buttons for the autolocker
Due to automation, I also was also fighting an INITIAL ALIGNMENT at some point. Taking H1 to DOWN for the morning crew.
I was able to fix the ALS X PLL by setting the crystal frequency to 0 MHz and waiting for the autolocker for about 30 seconds. The beatnote is now settled at 39.46 MHz.