keita.kawabe@LIGO.ORG - posted 23:39, Thursday 21 November 2013 - last comment - 15:46, Friday 22 November 2013(8681)
TMSX today (Jeff B, Andres, Alexa, Stefan, Keita)
Temp dogs were removed.
Isctex green periscope readjusted as it was close to the edge.
Tele beam position readjusted so the beam is centered on the primary.
Red extraction path was done.
High power beam dump path was done.
Working on IR QPD sled path.
Picomotor cable mystery.
It seems as if picomotor ordering is flipped somewhere between Beckhoff and in-chamber.
Picomotor in-vac cable has one DB25 (called J1) on one end and four smaller cables with mighty mouse connector (J2, J3, J4 and J5) on the other. In the cable drawing (https://dcc.ligo.org/D1000238) , these four cables are numbered such that the one closest to pin 1 of DB25 is J5, the farthest J2.
Both sites agreed that J2 goes to the green 50-50 splitter (M3), J3 to the steering mirror just upstream of the periscope (M6), J4 to the dichroic that steers the IR to the sled (M4), and J5 to the steering mirror just upstream of the IR sled (M14).
Now, the aluminum collar for the picomotor connectors are labeled as "A", 'B", 'C" and "D", and it's these labels that I and Corey used, assuming that A is J2 and D is J5.
However, in the cable harness routing diagram (https://dcc.ligo.org/LIGO-D1300007), the same cable is specified such that the one closest to pin1 of DB25 is "to M1", the farthest "to M4", it is ordered starting from pin 1 of DB25, so it's the opposite of the cable drawing. So A might be J5 and D J2, and this might be it. If so, we will re-rout the in-vac cables.
I have a vague memory that Corey confirmed that A is the closest to pin1, but I'm not 100% sure.
Since there's no way we can find which cable is closer to pin 1 without disconnecting DB25, and since there's a certain risk to disconnect and reconnect in-vac DB25, I'm asking Rich Abbott if he remembers which convention was used when labeling mighty mouse connectors.
Checking Cable (D1000238) In Lab
I pulled out two random (s/n S1104585 & S1105221) Picomotor cables to check how the four Mighty Mouse connectors are marked & where they are located. On both cables, they are marked in a way which matches the drawing/our guess for EX TMS (but not for Keita's memory for what I confirmed in-chamber in Sept):
I'm re-attaching photo/note of what we saw when we tested the Picomotor cable at the Test Stand next to the BSC (we observed the switched around order back in Sept):
(Alexa, Stefan, Kiwamu, Keita)
The convention at both LHO and LLO for the picomotor in-vac cables is as follow:
Unfortunately, the in-vac cables in HAM6 had cable "A" = J2 closest to pin 1 and cable "D" = J5 closest to pin 13; however the opposite is desired. This explains the switch. We have swapped the ABCD cables in vacuum, and now the picomotor controls are all correct. Success!
Moral of the story: be careful with the ABCD labellings on the picomotor in-vac cabling because they don't seem to be consistent. It would also be nice to have pin 1 labeled on the outside of the cable connector so that we do not have to disconnect it to know where pin 1 is located.