[Takase, Uchiyama, Ushiba]

We investigated the photosensor cables around BF and found that some of them have kink (and also strong wind from air supplier shakes these kink wires).
I twisted cables to remove kink and now wire have no kink at least from my eye.
When I was touching the cable around the kink, I could see some large glitches on the sensor, so it might be one of the source of the glitches.

Figure 1 and 2 show the photosensor signals before and after our work.
At least, visible glitches seem disappeard, but continuous check might will be necessary.

After the work, I also check photosensor spectra and confirmed H2 and H3 spectra become better (and almost nominal).
However, V3 photosensor have about 3 times larger noise after our work, so further recovery work is necessary for ETMY...

[rTakahashi, Ushiba]

Abstract:

Currely, all photosensor spectra look fine but there seems to be damaged cable between PF and BF.

Detail:

We checked photosensor signals of MN H2, H3, and V3 by touching cabes between PF and BF at just below BF.
Then, we could observe small glitch signals (fig1: example of H2 signals).

Afer that, we loose the screws of PEEK cable clamp because cables seem sandwitched too strong by PEEK blockes.
Then, we checked photosensor signals while touching the cable.
Though the glitches didn't disappear completely, glitch size and rate seem decrease.
So, we keep this situation.

Figure 2 shows the spectra of photosensors.
As you can see, some of photosensors have larger noise.
So, I compared the spectra with those during O4a (fig3).
There seems no sensors obviously become worse, so current situation might be happened even before O4a.

After these works, I checked the stock of the 3 m cables for cabling between PF and BF, and found 10 or more stockes.
So, probaly we can install new cables for these sensors if we have time and man power (maybe 1 - 1.5 days with 4 people including me and Takahashi-san).

[Dan, Hirata, rTakahashi, Tamaki, Ushiba]

We installed three additional cables between BF and PF (B49, B50, and B51).
Then, we replaced Dsub connectors on BF.
Followings are the cable numbers before and after replacement,

Old cables are cut and clamped on the BF.
We will continue the cabling at PF stage tomorrow.

Note:

During the work, we removed radiation shield plates between BF and PF.
They are stored in the cryostt, and need to be reinstalled after finishing the cabling.

[Ushiba, Tamaki, Komori, Takahashi]

We continued the photosensor recovery. The replaced cables were fixed onto the bottom of BF, the cable anchor (small hexagon), and the suspension rod with cable ties.

We connected the new cables to the photosensors and confirmed that the sensor is working.
Also, we checked the signals while touching the cables around BF but there seems no glitch.
So, new cables seems working well.

We will tie up the cables and fix them onto the payload.

[Tamaki, Ushiba]

We measured resistance, forward voltage, and inductance of the newly installed photosensor/actuator cables from the feedthrough flange at EYV.
All measured values are consistent with those during health check before O4a and seem fine.
Following table shows the summary of the measurement (with the values before O4a).

Also, we measured the resistance of all the other connections like 1-2, 1-3, and so on.
All values are OL, so we confirmed there is no unexpected short among the new cables.