J. Driggers, H. Yu, D. Sigg (reported by J. Kissel)

Jenne and Hang were having trouble getting ALS COMM locked this morning. The primary symptom was the COMM VCO didn't have enough range to push the PSL frequency toward the apparent COMM beatnote.
After a couple of red herrings (thinking it might have been a Tidal problem), Daniel -- with Jenne and Hang at the PSL racks -- helped trace the problem down by noticing that the LOMON on the COMM PFD throwing an error that the input particularly low (at -42 dBm, where we normally expect 12 dBm). 
The source of the problem was traced to a bad cable connection at the LO input to the dual PFD chassis COMM/DIFF -- the center pin of the TNC cable was busted and not making the connection. 

The entire N to TNC cable from the COMM FDD to the COMM side LO input to the PFD was replaced with a different cable.

We believe this cable was futzed with when Craig and Sheila were exploring ALS DIFF noise problems last night (LHO aLOG 44078, and while we don't know how long this cable has been bad, when they reconnected the LO, there intermittent-flaky-cable dice roll crapped out.

Note, as far as we can tell, this does NOT fix any of the problems that Sheila & company are investigating regarding excess noise.

Attached is:
 - A picture of the offending cable (with a rather meaningless label of "U29-LO RF 10-1"), 
 - A picture of the ISC rack R1 as is currently exists (after repair). The offending cable is highlighted in green.
 - Aome red (well green) lines on the existing cable wiring diagram "ALS_VCO_v2.pdf" found in D1200666. The -v11 of the diagram has several mistakes:
        - flipped the location of the DIFF and COMM usage in the dual PFD chassis, 
        - In input and output of the RF doubler are incorrectly flipped left-to-right, and
        - the RFPD patch panel has FOUR inputs not TWO. 
    The offending cable is in bold green on this (green)-lined diagram.