text: blog:log_monitor_now_checks_for_fs_activity [2014/06/17 03:39]
  + ====== Ke maintanance trip: backend ======
  + ​- ​ mk5ke is supplied with a 1200W Smart power supply. ​
  + ​- ​ mk5ke was successfully tested for recording and conditioning with two 16-TB modules.
  + ​- ​ mk5ke and mk5-2ke: recording, conditioning,​ autocorrelation,​ bit stats and pcal tests (pcalmon) were performed with both mk5's, swapping VSI cables and FILA OUT VSI outputs. ​
  + ​- ​ Pcal 5-MHz filter: tested, found to create fast phase wrap and introduce spurious signal in channels 5, 15, 16, thus discarded (pic -- pcalmon output graphs).
  + ​- ​ Pcal: pcal synch tone connected directly to the maser past the 5-MHz distributor. Levels regulated at the feed: added 3-dB attenuator to S-band. Current attenuation is 15dB in S-band, 0dB in X band. Amplitudes of the pcal signal before DBBC: X-band ~18dB, S-band ~15dB.
  + ​- ​ DBBC: FILA OUT and Core2 boards inspected, connections checked. Secured VSI cables inside the DBBC with cable holders in order them not to pull on the VSI connectors.
  + Problems revealed: ​
  + ​- ​ mk5ke: pcal signal extracted from the data recorded with mk5ke is "​stuck"​ at one level, doesn'​t vary with time (under the same conditions the signal from mk5-2ke looks "​naturally"​). Problem is nether related to a cable nor to the VSI connectors on FILA OUT. VSI IN connector on the back of mk5ke?
  + ​- ​ mk5ke and mk5-2ke: refuse to condition just one module. Always conditions module in bank B when two modules are in, both VSN's are lost. Recommendations for use: when conditioning,​ put the module to be conditioned in bank B. Put dummy erased module in bank A. Condition as normal. Swap modules if necessary. After conditioning,​ repair electronic VSNs of both modules.
  + ​- ​ Pcal: all tones over the passband are visible on spectrum analyser, but 10-kHz are suppressed by DBBC (pic pcalmon output).
  + ​- ​ DBBC: "stuck bit" and bit statistics problems related to VSI OUT connectors: ch15 (S) with VSI1 (rear) -- was problematic from the beginning, ch5 (X) with VSI2 (front) emerged after the inspection and refitting of FILA OUT board.
  + ​- ​ Modules: hob+025/​6000 was found to have faulty disk among 6/7. Is labeled as broken and prepared for repair.