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    User name V. Sulkosky/B. Moffit

    Log entry time 08:25:19 on October 26, 2008

    Entry number 244721

    keyword=BPM and Raster ADC's Saturating

    We were called in this morning to investigate the missing BPM and Raster
    signals. As it turns out with beam, these signals are saturating the
    ADC channels we are using in an 1881. This was not caught with cosmics,
    since the signals were showing up. However, the raw signals were at
    channel 8000 or above.

    Bryan and I made an access to fix this problem without beam the BPM
    signals coming from the attenuators was typically -70 to -80 mV. These
    values should be less than -50 mV to avoid saturation. I set all the
    BPM and raster signals to be about -35 mV without beam.

    As far as I know the settings for the attenuators were not changed, but
    the signals were teed-off to send them to the BigBite weldment. This
    might have resulted in a change in the signal going to the HRS.

    Currently there is no raster signal going to BigBite. The attenuator is
    on the floor providing a negative signal and the ADC requires a positive
    signal. So we unplugged the tee going to BigBite. The signals are still
    going to the left and right HRS.

    The problem should be fixed now, but I will keep an eye on it.

    A copy of this log entry has been emailed to: moffit,rom,brads,camsonne