[Keita, Daniel, Karmeng]
Particle counter acting up (black screen when we move the stand, and high particle count for the first three measurement). Picture for comparison with hand held counter.
We remove all three cables connected to the old OPO, the PZT cable is wrapped with a foil as a marker.
The old OPO is removed, wrapped and kept in the bag used to store the new OPO. New OPO is placed in the chamber, but not bolted on.
The trick to disconnecting the OPO cables was to install one flat dog on the front-right side of the OPO base, then remove the flat dog we had placed on the rear-left side of the OPO assembly earlier this week. This allowed us to slide the OPO back a bit and angle it up slightly so that the connectors were accesible and could be removed. Keita was able to hold the OPO in this position with one hand and loosen the jacking screws with the other (we thought this would be safer than trying to hold the OPO vertically above the VIP). We have a photo of this that Kar Meng may post later.
I first tried to undo the screws for the PZT cable connector on the OPO without lifting the OPO, but managed to hit the SFI1 (the one close to the -Y door) with a steel allen key twice. The wrench is tiny but we didn't want to repeat it many times.
Initially the OPO posotion was VERY tightly constrained in all directions (like within 0.5mm range). In addition to the dog clamps installed as the position reference that restricted the motion in -X and +Y direction, there was no room to move in +X and -Y (end not much in +Z) either because the metal ferrule thing at the back of the PZT connector hit the SFI1. Lifting OPO means that the PZT cable will be badly kinked. That's why we changed the position references of the OPO from (one left, one back) to (one left, two front).
After that, I was able to push OPO in +Y direction and lift the entire thing (with the cables still attached). I thought about the second person undoing connectors while I'm holding the OPO mid-air, but Daniel came up with the idea that I will only lift the front edge of the OPO to tilt it just enough so the cable connectors and the allen key stay safely above the SFI1. I didn't have to bear the load of the OPO while undoing the connectors, it was much safer than my alternative.