michael.rodruck@LIGO.ORG - posted 14:34, Wednesday 06 February 2013 - last comment - 11:45, Thursday 07 February 2013(5390)
60 Hz noise gone
Turns out we left cables attached to the TFIN and TFA/B inputs on the PMC field box in the racks, with the MEDM switch enabling the TF path. Removing the cables got rid of the noise, and I disabled the path. There is still some 60 Hz noise but it is nothing like it was before.
This is something we've forgotten since the science run ended...always check the cables when noise hunting!!
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Checked the PSL PDA spectrum and ODC lock status again this morning and all looks fine. Thanks for following this up Michael.
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Excess power diagram of the past day or so. It's very clear that the high frequency noise diminishes and disappears in the recolored channel right around the time that the problem was corrected.
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