German,
Check the cup configuration switcher behind top front panel. If recently  that
panel was moved you could accidentally switch system onto more sensitive
resistor.
Sergey.

>===== Original Message From Stable Isotope Geochemistry
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>We have a problem with our Conflo-III system, which is attached to a Delta
>Plus XL. When we turn on any of the reference gases (CO2 or N2), we get a
>large signal (>14 volts).  My first thought was that the pressure was too
>high. We decreased the pressure using the gauge in the Conflo unit, but
>there was no luck. We checked the pistons and the distances of the
>capillaries inside the open split glass cell when they are on and off, and
>all of them are ok.  I also thought that we were not getting any or low flow
>of helium. We measured the flow of the helium stream entering the open split
>glass cell and it is what is expected (~2 ml/min).  We even disconnected the
>EA to see if somehow the problem was with the EA, but we still see the same
>problem.  What makes this problem so particular is that when we turn on the
>CO2 reference gas we only get a large signal on mass 44. Masses 28, 40, or
>18 only show a slight increase. When we turn on the N2 reference gas we only
>get a large signal (>14 volts) on mass 28, not on any other mass.  I ran out
>of ideas, so I would  really appreciate any help.
>
>Thanks,
>
>German

Sergey OLEYNIK, PhD
Ecology and Evolution
Dept. Biological Sciences
University of Illinois, Chicago
845 W. Taylor st.
UIC, 3342 SES
Chicago, IL 60607
Phone: office 312-9964584
lab 312-3550600 (voice)
Fax: 312-4132435
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