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#     #   # #           #     #  #   #   #    #     #    #
#     #    #             #####   #    #  #    #     #    ######

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Problem:
--------


      It has been experienced some times that an individual HV CAEN crate
set itself to 0 when it is in a Runnable or Injectable HV setting, without any
HV channels trip and no further clue of what caused it.


Diagnosis:
----------

	- There is NO SOFTWARE control that groups all the channels 
of a single HV CAEN crate. They are grouped as IFR, or as individual 
HV channels. Therefore the problem reported above has a HARDWARE ORIGIN.

	- Historically the explanation was a hypothetical huge spark 
from one of the chanmbers  that caused the HV crate to get reseted. 
NO EVIDENCE OR PROVE OF THAT STATEMENT HAS BEEN FOUND SO FAR.

        - The same effect was reproducdd when the SIAM interlock cable was pulled
off the HV CAEN crate. The SIAM alarm was not latched, but the kill signal on the 
HV crate was triggered reseting the HV crate.

        - Shorting the SIAM interlock alarm (to discard any cable problem) that
the problem occurred again.


Conclusion:
----------

        - we traced that back to a faulty connector in one of the HV
plexi-glass distribution boxes.


Fix:
----


    - The first (temporary only) solution is ask the shift crew to power 
cicle all the HV channels of the HV crate that got auto-reseted. That DO NOT 
cure the problem, but may bring it back on until the next occurrence.

    - Identify the faulty BOX (look for high current channels,...that's a 
hint only to start ...). If there are spare connectors in the BOX, use the 
spare ones until you see that the problem does not appear again. 

    - Replace that PLEXI-GLASS BOX, ASAP (that will save you lots of pages in the
middle of the night, believe me!)




Posted on 08/07/2001 by Eugeni Grauges