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VIS (IX)
naohisa.satou - 9:08 Wednesday 30 June 2021 (17335) Print this report
Checked resistance of TF and BF LVDT actuators coil.

on 2021.6.29

Conductivity check was done on BF and TF LVDT Acutuator Coil.
I measured the resistance from the feedthrough. Both seem to be disconnected at some point.
I looked for the breakage point, but it is most likely that BF is broken inside the filter body.

Checked cables
BF Cable name: BF LV, Pin No.3-8
TF Cable name: TF LV, Pin No.3-8

 

Non-image files attached to this report
Comments to this report:
ryutaro.takahashi - 20:52 Wednesday 30 June 2021 (17345) Print this report

[Takahashi, Sato, Sugiyama]

We went to repair of broken cables.

  1. Opened the top chamber.
  2. Removed the ballasts on the TF and the yoke for the TF.
  3. Repaired the cable for the TF actuator. The pin for the lead cable of actuator coil was replaced.
  4. Fixed the BF.
  5. Removed some primary and secondary coils of BF damper.
  6. Pushed down the TF keystone so that the F1 can reach the release sensors.
  7. Removed the connectors from the side plates on the BF cup.
  8. Removed the screws for the BF cup.
  9. Pushed up the TF keystone upto the upper limit. The BF cup was opened.
  10. Repaired the cable for the BF actuator. The pin for the lead cable of actuator coil has been disconnected from the socket. Some pin/socket for LVDT/actuator were replaced.
  11. Pushed down the TF keystone. The BF cup was closed.
Images attached to this comment
ryutaro.takahashi - 21:28 Thursday 01 July 2021 (17354) Print this report

[Takahashi, Sato, Sugiyama]

  1. Recovered the cables around the BF.
  2. Attached the primary/secondary coils for the BF damper.
  3. Connected the additional spring on the BF.
  4. Mounted the ballasts on the TF. Set the TF keystone to -18mm.
  5. Checked the cable connection from the BF to the feedthroughs. Some cables (DSCH, DSCV) were disconnected. They were repaired.
  6. Released the BF and the cryo-payload. The height of BF was 74mm. LVDT singals of F1-F3 showed almost nominal point. The BF keystone was lower than nominal point by 1mm.
takafumi.ushiba - 22:30 Thursday 01 July 2021 (17357) Print this report

When I released the cryogenic payload, I felt platform going down by 3-4 mm lower.
Also, earthquake stops for the recoil mass is very close to the RM (~2 mm or smaller) although I didn't touch them during this work and their nominal distance is roughly 5 mm.

Probably we need to check the height again at some point.

naohisa.satou - 13:25 Friday 02 July 2021 (17367) Print this report

photo of the disconnect cable.

Images attached to this comment
ryutaro.takahashi - 17:50 Friday 02 July 2021 (17377) Print this report

[Takahashi, Sato]

  1. The primary coil of BF LVDT was touching the secondary coil. Adjusted the position of secondary coil.
  2. Pulled up the additional spring on the BF. The BF keystone went to 68mm (2900count) in height.
  3. The cable for the TF LVDT was disconnected in the Dsub connector on the IP. It was recovered.
  4. Adjusted the ballasts on the TF. Two rectangular blocks of 1.8kg were removed and small disks of total 0.2kg were added. The TF keystone went to -16mm in height.
  5. Adjusted the yaw FR so that the primary coils of BF damper can part from the secondary coils.
  6. Released the IP. Closed the top chamber.
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