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Entry  Fri Feb 19 15:12:38 2016, Koji, Summary, PEM, Guralp Health Check Guralp_Raw_PSD.pdflow_vel_comparison.pdfGuralp_TF.pdf
    Reply  Wed Mar 23 15:23:12 2016, Steve, Summary, PEM, Guralps as connected GUR_A.jpgGUR_B.jpgGUR_Interface_Box.jpg
       Reply  Thu Mar 24 08:20:52 2016, Steve, Update, PEM, Guralp-A calibration sheet 
       Reply  Fri Mar 25 19:17:28 2016, Nikhil, Update, PEM, Guralp Seismometers 16x
          Reply  Fri Mar 25 23:54:04 2016, rana, Update, PEM, Guralp Seismometers 
       Reply  Wed Aug 3 14:52:37 2016, Steve, Summary, PEM, Guralps as connected 
          Reply  Tue Aug 9 13:53:57 2016, babbott, Update, SEI, long Guralp EX cable repaired on the D-sub side 
             Reply  Tue Aug 9 19:35:49 2016, rana, Update, SEI, both Guralp seismometers are functioning and being acquired 1goodday.png
                Reply  Wed Aug 10 10:32:44 2016, Steve, Update, SEI, working Guralps as they are 6x
                   Reply  Fri Aug 12 14:37:34 2016, Steve, Update, SEI, working seismometers as they are eq_2.1m_Geysers_CA.pngeq2.1m_GeysersCA.pngoscillations.png
Message ID: 12389     Entry time: Tue Aug 9 19:35:49 2016     In reply to: 12385     Reply to this: 12391
Author: rana 
Type: Update 
Category: SEI 
Subject: both Guralp seismometers are functioning and being acquired 

After some cable swapping, we now have both Guralp seismometers running and the times series and spectra look similar to each other and motley blushhealthy.


Bean and I took a look at the whole situation today. Ben had nicely fixed the Dsub end of the EX cable (the EY one is still just a sad joke), After installing this newly fixed cable, we still saw no signals. There was some confusion in the control room about using the MED displays to diagnose seismometers: flickering MEDM values cannot be used for this. It would be like checking a pizza box temperature to determine if the pizza is any good.

  1. Although the +/- 12V LEDs on the front panel are dim, we confirmed that the produce 11.94V even when loaded with a seismometer. So its a LED circuit problem not a power problem.
  2. We were able to inject signals into the front panel with a breakout board and see them in DV for Input 1, but not Input 2.
  3. After Ben left, I kept poking around and found that the Guralp chassis output gets broken out into 3x3 BNC cables before going to the PEM BNC panel (and then on to the PEM ADC). This is where the problem was.
  4. The Input #3 BNC cables were connected to the long cables going to the 'GUR2' channels of the PEM. The Input#2 BNC cables were connected to some short BNC cables that were just hanging from the rack. So, somewhere during the debugging of the past N months, someone plugged this in wrong and didn't notice or forgot to switch it back. So all of the tests using DV or DTT or MEDM since that time have been invalid.

 

Tomorrow, Lydia is going to change all of the labels and channel names. The new names will be EX & EY to prevent this kind of huge waste of time with channel name swapping. That means no more illegal names with the label maker, Steve.

From the spectrum you can see that the EX seismometer (GUR2) is still not centered or at least its oscillating at 245 Hz for some reason. This should go away after some power cycling or recentering using the magic wand.

I noticed some anomalies in the mechanical setups at the ends:

  1. Some junk has been stored on top of the EX seismometer. Please never, even temporarily, store your power supplies, tools, or donutsfrown on top of the vibration sensitive sensors. Just put it on the floor and improve your carma.
  2. The EY seismometer has some fishy wires being fished between the can and the rubber seal. This is verboten. That seal must be flush to prevent pressure fluctuations and wires in there will ruin the smooth contact permanently. Temperature sensor wires must go through the grantie block feed-through or else its pointless.
  3. The flimsy insulation on the EY seismo is waay toooo mickey mouse. Real thermal insulation should be done using the yellow foam that Jenne used for the seismo huddle test. This flimsy silvery stuff is OK for making hats and mittens and beer cozy's, but its not research grade foam.
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