keita.kawabe@LIGO.ORG - posted 17:43, Monday 07 March 2022 (62092)
HAM6 OMC PZT grounding: No change after pumping down
Some people wanted to check if the grounding changed after pumping down though there's no reason to suspect that, so I checked and nothing changed.
There's still no mysterious ground break for the PZT shield.
PZT, QPD and DCPD shield are all connected together inside but are isolated from the chamber.
Grounding inside the chamber is still represented by by this diagram in alog 61095.
What was done:
Power down DCPD from the front panel of the whitening chassis. Power down QPD transimpedance amp. Disconnect PZT HV supply and power down the PZT driver chassis.
Disconnect DCPD (D6-F1), PZT (D6-F2) and QPD (D6-F3) cable from the feedthrough.
Use breakoutboard boad and check continuity between PZT feedthrough pin 13 and other things.
| Chamber ground | QPD FT pin 13 | DCPD FT pin 13 | DCPD FT signal GND (pin 15) | DCPD FT signal GND (pin 16) | |
| PZT FT pin 13 | Isolated | Continuous | Continuous | Continuous | Continuous |