Displaying reports 81201-81220 of 83528.Go to page Start 4057 4058 4059 4060 4061 4062 4063 4064 4065 End
Reports until 18:15, Friday 09 March 2012
H2 AOS
keita.kawabe@LIGO.ORG - posted 18:15, Friday 09 March 2012 (2406)
TMS vibration absorber reinstalled

Following advice from Fabrice and Callum, I and Dan rotated them 90 degrees and put them in a (hopefully) correct direction.

We didn't use thick washers between the absorber flame and the base plate, partly because it would have been a pain to do so, partly because the screws available were somewhat short (it didn't go all the way through the base plate) and using washers would have reduced the number of screw threads that were engaged.

Images attached to this report
H2 CDS
david.barker@LIGO.ORG - posted 16:41, Friday 09 March 2012 (2404)
all front ends except PSL running rig 2.4.2

The ISI, HPI and TMS models were fixed and now all the H2 frontends with the exception of the PSL are running RCG2.4.2.

We found a DAC/ADC reconfiguration problem on h2seib8, which Rolf is investigating. I had some timing issues at EY when restarting the SUS frontends, which I cannot reproduce.

SUS FMX will not compile, I've taken it out of the DAQ for now.

X1 SEI
hugo.paris@LIGO.ORG - posted 15:49, Friday 09 March 2012 (2403)
HAM-ISI Unit #2: transfer functions measurement over the weekend

X1 HAM-ISI Simulink model does not have more than 3 ADCs. Earlier today, CDS team confirmed that it was safe to run unattended excitations on HAM-ISIs, in the staging building.

A quick Transfer Function measurement (2h) was performed on HAM-ISI Unit t#2 today. DAC output channels were monitored. No abnormal behavior was observed.

Transfer function measurements, and their excitations, are running on HAM-ISI Unit #2 over the weekend.

H2 SUS
betsy.weaver@LIGO.ORG - posted 15:10, Friday 09 March 2012 - last comment - 18:01, Friday 09 March 2012(2402)
H2 ITMy BSC8 extraction
Today, Travis, Jason and I finished extracting the ITMy lower QUAD structure.  There was a small issue with the elevator controller unit in that it failed to lower all the way.  We addressed this issue by swapping it with the controller from our second elevator setup (having backups is a VERY good thing).  We also encountered some interference between the optic stop "fingers" and the arm, resulting in removing the fingers altogether and reseating the elevator on the QUAD.

The QUAD was removed from the BSC repair arm and inserted into a lower structure storage container for it's flight back to the fiber welding cleanroom in the LVEA.  Currently, it resides in the storage container in an anterior cleanroom awaiting disassembly and a decision on the path forward.  Dale Ingram documented most of the extraction process by camera and his pictures/videos should somewhere sometime.  
Comments related to this report
dale.ingram@LIGO.ORG - 18:01, Friday 09 March 2012 (2405)
Two photos of the extraction are attached.  The collection sits in ResourceSpace.  Rodney Haux shot the preparations on 3/8.  In RS, sort the photos by date (click twice?) and you should see them in the proper order.
Images attached to this comment
H2 CDS
keita.kawabe@LIGO.ORG - posted 19:24, Thursday 08 March 2012 - last comment - 14:55, Friday 09 March 2012(2398)
Ground loops: TMS and ISC are good, SUS and TCS are not

We continued our investigation by disconnecting everything under the ISI table from outside.

As it turned out, all TMS and ISC cables are fine, but using DVM with alcohol-wiped tips we identified problems in SUS BOSEMs and TCS ring heater:

  1. L2 (penultimate mass) BOSEM cable shield,
  2. L1 (second mass from the top) BOSEM cable shield,
  3. Ring heater cable sheild

are all locally (i.e. in-vac) connected to the metal structures, and if you look closely it's really obvious (Rich said "How can this NOT be grounded?!").


ETM/ERM:

The first picture shows the cable connector clamp on the penultimate mass. Can you see that the clamp doesn't have any insulation? It's just two metal plates sandowitching the metal connector shell. Of course the penultimate mass is electrically connected to ISI via suspension wire.

Also, a pinching clamp for the cable (only the bottom half of which is shown at the top of the photo) doesn't have insulation, though the cable itself has an insulation mesh.

I couldn't take a good picture of the L1 connector clamp, but it's the same design.

This is a serious ground loop right there for SUS (but not for ISC and TMS) and we should discuss any possible fix.


TCS:

The second picture shows the elaborately designed cable bracket thingie that directly connects the ring heater cable shell to the mirror cage.


ISI:

We haven't disconnected ISI cables simply because there are many,  and we know that the ISI cables are going to be revisited after the cartridge insertion. But somebody should do that to see if there's some funny thing is going on like SUS and TCS (and ISC/TMS before we fixed one clamp problem).

We just looked around and saw two cable shield rings resting on metal bolt of ISI (third and forth picture).

Images attached to this report
Comments related to this report
betsy.weaver@LIGO.ORG - 14:55, Friday 09 March 2012 (2400)
I was able to sneak out to Ey and disassemble the brackets which were causing the ground fault on the QUAD (SUS ones, not TCS ones).  Rich will continue his "Ohming", but I will need to redress these brackets/connectors.  I have the Reaction chain UIM and PenRe clamped. 
LHO General
patrick.thomas@LIGO.ORG - posted 18:36, Thursday 08 March 2012 (2397)
plots of dust counts
Attached are plots of dust counts > .5 microns.
Non-image files attached to this report
H2 CDS
david.barker@LIGO.ORG - posted 18:31, Thursday 08 March 2012 (2396)
ITMY problem found in RCG code, fix installed as version 2.4.2

Rolf and Dave

Report on ISI driving of ITMY March 1st 2012

The problem is introduced by the addition of a fourth ADC into the hepi/isi models. There is a hard limit set in the code for the decimation filtering history arrays to only support up to 3 ADC modules. The addition of a fourth caused the ADC decimation filtering history to write into the space used for DAC upsampling filer history data, thereby causing some form of this ADC input to be output to the first DAC module. I believe this has been in the code since the early blue box days. While other arrays used by ADC/DAC data have been updated to use MAX_ADC_MODULES and MAX_DAC_MODULES some time ago to set array sizes, as defined in cdsHardware.h (presently 12 ea), these history arrays apparently got overlooked. This hard limit would not effect IOP tasks, or any models running at 64K, as they do not perform up/down sampling.

a new rcg tag 2.4.2 was created as a copy of 2.4.1 with the MAX ADC/DAC substitution installed. All LHO models were recompiled and restarted against 2.4.2. with the exception of:

h2susb6: h2sustmsy model would not compile, missing links. Running 2.4.1 on this front end for now

h2seib6: would not reboot, needs further investigation

h2psll0: hold off until friday, running 2.4.1 on this front end for now

LHO General
jonathan.berliner@LIGO.ORG - posted 16:41, Thursday 08 March 2012 - last comment - 07:27, Friday 09 March 2012(2395)
Thursday Aft Ops Log
[Continuing from Corey]
- Retractable arm inserted on BSC8, H2ITMY Quad removed.
- Many high (10k-30k) dust count alarms in the Biergarten, but the offending dust monitors could not be located. The only dusty activity during much of this time was vacuum cleaning in the area and retractable arm installation by the door of BSC8
- CDS worked on cornering the H2ITMY fiber-breaking issue. Many reboots of h2seib6, h2seib8, and the entire DAQ as code and models were updated.
- H2 PSL and CDS are working into the evening.
- OSB doors locked at 1630.
Comments related to this report
betsy.weaver@LIGO.ORG - 07:27, Friday 09 March 2012 (2399)
In fact, we did not remove the lower QUAD.  The arm was mated to the lower QUAD, but felt that was a good stopping point for the night.  The arm is parked inside the chamber.  
H2 SEI
hugh.radkins@LIGO.ORG - posted 12:48, Thursday 08 March 2012 (2394)
BSC8 HEPI Horizontal Actuators disconnected from Crossbeams
The SEI Engineers at MIT were a bit concerned about letting the horizontal actuators take the full shear of the vertical motion when the Quad payload is removed.  So, I disconnected them.  Almost completely that is...  The SE unit has a bolt that I fear is galling.  Everything else that can has been loosened and there are slots so we feel this will be OK.
LHO General
corey.gray@LIGO.ORG - posted 12:35, Thursday 08 March 2012 (2393)
Ops Midday Shift Summary
LHO General
patrick.thomas@LIGO.ORG - posted 08:05, Thursday 08 March 2012 (2388)
plots of dust counts
Attached are plots of dust counts > .5 microns. The dust monitor in the clean room over BSC8 (H0:PEM-LVEA_DST15_5) was momentarily disconnected, but this does not really show up in the included plot of H0:PEM-LVEA_DST15_MODE.
Non-image files attached to this report
H2 CDS
keita.kawabe@LIGO.ORG - posted 23:38, Wednesday 07 March 2012 - last comment - 00:06, Thursday 08 March 2012(2390)
Cornucopia of (potential) ground loop at EY

I and Dan confirmed that shells of ALL in-vac cables that are connected to CDS side are grounded to the metal parts of ISI and TMS. I'm talking about all cables related to ETMY, ERMY and TMSY. There is a huge potential risk of ground loop(s).

The cause of this is NOT in four ISC cable chains (picomotor, beam diverter, and two QPD cables). This was confirmed by disconnecting all ISC cable chains from the CDS side at the moc feedthrough: When we did this, the shells of disconnected in-vac cables were isolated from the metal parts of ISI/TMS.

We haven't exonerated the two BOSEM cables of TMS yet, as well as all ETMY and ERMY cables.

What is likely happening here is:

Even though there seems to be no DC-coupled "loop" as far as ISC table/cable is concerned in the above picture, basically the ISC cable shields on the ISC table are within 1/32 inches or so of the table surface for the entire length and there certainly is a capacitive coupling. And if there are two crappy cables, they form DC-coupled loop, even though that's not ISC. This is bad.

One crappy cable might be the cause of the entire thing.  I can continue testing the remaining two TMS cables, but if we're unlucky we might need to check each and every in-vac cable including ETMY, ERMY, TCS and ISI cables, and I need cooperation from all parties.

Images attached to this report
Comments related to this report
keita.kawabe@LIGO.ORG - 23:53, Wednesday 07 March 2012 (2391)

We fixed one crappy cable clamping today.

One of the peek cable clamps was squeezing four ISC cables really tightly, and this was causing some problem to the picomotor cable. Either the shielding of the cable was shorted to the shielding of one of the QPD cables, or it was directly shorted to the ISI table. (The symptom was that the shell of the picomotor cable was grounded to the ISI table even though the picomotor cable was not connected to CDS.)

Due to the position of the picomotor cable in this cable clamp, we cannot confidently say which was the case, but anyway once we made the spacing of the peek clamps a bit wider (second picture), the problem was gone.

Images attached to this comment
keita.kawabe@LIGO.ORG - 00:06, Thursday 08 March 2012 (2392)

How is IY? Have SEI/SUS people confirmed that there's no potential ground loop there?

H2 SUS
betsy.weaver@LIGO.ORG - posted 20:23, Wednesday 07 March 2012 (2389)
BSC8 ITMy repair work
After pulling back the ACB and removing a few panels of flooring, QUAD vibration absorbers, sleeve and Fiber Guards we made more inspections of the ITMy weld horns.  The following collection on ResourceSpace is of the shortest broken horn:

https://ligoimages.mit.edu/?c=1002

We do not see any cracks further down into the horn or ear.  We used a swab wipe to brush away some of the debris on this ear in order to facilitate further inspection, hence why some of the pictures may look a little different when compared.
H1 PSL
michael.rodruck@LIGO.ORG - posted 16:53, Wednesday 07 March 2012 (2387)
H1 PSL installation

HEPAs are installed, ceiling and several wall panels have been left off for electrical inspection. Gang plates were installed. Gerbig has left but will be coming back in late March.

Images attached to this report
H1 SEI
greg.grabeel@LIGO.ORG - posted 17:30, Tuesday 06 March 2012 - last comment - 15:26, Friday 09 March 2012(2369)
A tale of two pods

Pods #94 and #71 were experiencing the problems laid out in alogs 2308 and 2321. So today I de-podded both of them. During the de-podding I noticed no issues with the feet or any other kinematic devices.

I did find a broken flexure on #71, however (pictures attached). Which is odd since the GS-13 tested fine on arrival. Somewhere in between its arrival and testing it completely failed. It's possible it was severally fatigued during shipping and only recently failed.

Pod #94 has had its brains swapped with another failed GS-13 (mechanical issues) and will hopefully be tested sometime tomorrow to see if that solves the gain issues. If not that should point us toward some mechanical problem that I haven't seen before.

Both of these pods will become test pods (if their issues can be fixed) until they can be sent to LLO for retesting.

Images attached to this report
Comments related to this report
hugo.paris@LIGO.ORG - 15:26, Friday 09 March 2012 (2401)

A Huddle test was performed earlier this week in order to evaluate the effect of the reparations.

  • Pod #94 does not feature a gain of 1/2 anymore. It confirms that its pre-amp was initially malfunctionning.
  • Pod #71 does not output signal. It did output signal before having its flexure replaced. It is possible that an electronic mis-connection was caused during de-poding/repoding process.

Results and pictures of the test are attached.

Non-image files attached to this comment
Displaying reports 81201-81220 of 83528.Go to page Start 4057 4058 4059 4060 4061 4062 4063 4064 4065 End