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.

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 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.

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.  

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).

Attached are plots of dust counts > .5 microns.

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

[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.

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.

• Flurry of activity continues around BSC8
• Apollo is surveying/laying foundation for Mode Cleaner Tube display
• Vern/Vincent physically disconnected power cables from ISI Coil Chasis for continuing diagnosis
• Dave implemented a model change for ISI and this required a DAQ reboot
• Brazing of refrigerant lines is taking place in Kyle's Mechanical shop
• Have had Dust Monitor #15 Major Alarms (nothing over 500 counts this morning)

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.

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:

• There is one or more crappy cable clamp which physically grounds the cable shielding to the metal in-vac parts.
• Cable shields are connected to pin 1 in-vac, which is connected to pin 13 out-of-vac.
• Pins 13 are connected to each other on CDS side.
• Thus, the shell of any good cable is connected to the metal in-vac parts via CDS and crappy cable.

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.

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.

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.

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.