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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