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    User name brads/kalyan

    Log entry time 10:47:23 on November 03, 2008

    Entry number 246423

    This entry is a followup to: 246418

    keyword=MWDC power supplies good, but cards are oscillating...

    We checked the power supply and threshold voltages on the power buses in the stack for chambers 1, 2, and 3. All were fine (power rails were at 6V, thresholds were at the setpoints).

    Level translator card power supply voltages were also fine.

    Kalyan checked the output of a level translator card on chamber 3: it showed a regular oscillation with a period of 125ns and a pulse width of 25ns. The equivalent output for a chamber 1 card was clean (as it should be).

    Since raising the threshold voltage for chambers 2 and 3 gets rid of the oscillation the problem seems to originate at the A/D cards. However, the supplies voltages are all good -- damned if I know what to check next...

    We will raise the thresholds on chambers 2 and 3 to get rid of the symptom and continue with the program. Need more ideas from experts for troubleshooting tomorrow.

    A copy of this log entry has been emailed to: xqian