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    User name sarty

    Log entry time 04:28:06 on May22,2002

    Entry number 3907

    keyword=Problems with Raster Gain and getting Raster to turn on

    Between 00:00 and 00:40, we tried to get the raster size set back to our normal
    size (about 1.7mm square according to spot++). MCC was unable to get size
    big enough with their controls, and we were eventually advised to increase the
    raster gains using the knobs labelled "X PGA" and "Y PGA" below the raster
    oscilloscope in the counting house (this advice from Bill Gunning from Acclerator,
    and confirmed by Bodo Reitz).
    .
    We increased the apparent gain (according to watching the raster scope trace)
    with the PGA knobs by about 4 times (and moved scope voltage settings from
    1 V/division to 5 V/division). This change looked like it might have succeeded in
    giving the desired spot size, but before getting a chance to check it out, we lost
    beam ("orbit problems").
    .
    Once beam was recovered (01:55), MCC was unable to get raster turned back on
    properly. It appeared to be on at very much (much) lower gain than previously,
    and even attempts to "max out" our PGA knobs were only able to make the true
    raster spot-size (according to spot++) about 0.5mm square (or less). We put
    the PGA knobs back as close as we could to where it looked like they should
    work prior to losing the beam to the orbit-problems.
    .
    Eventually, MCC attempts a reboot of the IOC that controls the raster, but then
    was unable to regain communication with it. By 3:00, they are going downstairs
    to hard-reset the IOC. (See Owl Shift Summary for more gory details...)