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    User name R. Michaels

    Log entry time 08:44:20 on January 25, 2009

    Entry number 257735

    This entry is a followup to: 257726

    keyword=re: Fastbus problems last night

    The odds of two crates simultaneously losing power supplies are remote (maybe a power
    surge ?). This suggested a common origin to the ROC9, ROC10 problem. One thing they
    have in common: chamber signals.

    When Kalyan reported that the fastbus test codes showed a never-ending stream of hits,
    instead the usual 96 hits per TDC, this suggested oscillations in the frontend.

    In "theory" the DAQ should be stable if enough memory is allocated for the event, and if the
    readout is truncated to not exceed this memory. In that case it has very high deadtime but
    doesn't crash. (I haven't checked the parameters on BB for awhile, though I do not suggest
    changing anything at this stage. )

    It might crash with huge noise even if your parameters are correct (I've seen this on the HRS,
    though it is rare -- usually the HRS just gets huge deadtime).

    A copy of this log entry has been emailed to: kalyan@jlab.org,segal@jlab.org