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    User name R. Michaels

    Log entry time 12:28:02 on March17,2006

    Entry number 167041

    This entry is a followup to: 167025

    keyword=Flipped TS cable

    We verified with an ohmmeter that the ribbon cable that carried triggers
    to the trigger supervisor (TS) has a flipped polarity,
    which would indeed make the TS trigger on the trailing edge as
    confirmed by Ed Jastrzembski (TS inventor). By design the TS
    should trigger on leading edge, but if the polarity is flipped ...

    The way it happened was that the NIM/ECL has "+" on the left but
    the TS has "+" on the right. Our only excuse is that the connector
    inputs are keyed so its not easy to flip polarity, but that doesn't
    help if the keys are flipped ! Also it was not easy to notice during
    setup because the trigger widths are normally stable. So all timing
    was set up correctly; however, if during the experiment some trigger
    develops after-pulsing or long-pulses it can cause trouble (the
    effect Brad was observing in halog 167025).

    We are in the process now of making a longer ribbon cable to TS
    which will compensate for the 80 nsec delay of the gate widths.
    This is the easiest solution because it requires no change to timings
    downstream. Once we get this cable made we'll double check all
    timing on a scope. Sergey is hunting for a long ribbon cable ...