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    User name M. Stevens

    Log entry time 18:43:10 on April 16, 2007

    Entry number 199270

    keyword=Left Q1 spurious trips

    Troubleshooting Left Q1's spurious trips, we could find no obvious cause. We replaced all of the optocouplers on the power supply mother board, reasoning that a radiation-damaged optocoupler could be the cause. Then we lost communication via the serial link from the ioc. Also, the local control panel stopped working. We corrected an out of position optocoupler by re-inserting it into its socket. This fixed the local control panel. We tried different program chips on the mother board, and replaced the serial driver chips, all with no joy. Then we decided to check the configuration of the dip switches, two of which were physically close to the chip manipulation efforts above. Bingo - one of them had been changed, presumably by an accidental bump of the switches. We corrected the configuration, and everything now works fine. We also bypassed the 240V uninterruptible power supply internal to left Q1's Danfysik power supply, because there was an error indication on its control panel (and the spare ups failed to function correctly). Hopefully one of these measures has cured the spurious trips.

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