At 11:51 AM 10/9/02, you wrote:

>ISODAT IS FAMOUS FOR.  SEVERAL TIMES PER MONTH AND SOMETIMES SEVERAL
>TIMES PER WEEK WE GET DURING A RUN A GREEN ERROR SCREEN WHICH SAYS
>"GCEVALO:  NO PEAKS FOUND"  MODUL 33083 INFO NUMBER 258.  PRESSING
>ESCAPE CAUSES THE SYSTEM TO RESUME THE RUN WITH THE LOSS OF THE DATA
>POINT AT WHICH THE STOPPAGE OCCURRED.  THIS HAPPENS ON BOTH DUAL GAS
>RUNS DURING THE RUNNING OF THE SECOND GAS AND DURING SINGLE GAS RUNS.
>WE ARE CONFIDENT THAT SAMPLES ARE GOING THROUGH THE SYSTEM NORMALLY AND
>PEAKS SHOULD BE DETECTED BUT FOR SOME REASON ARE NOT.

Sounds like the old lost signal in the second cup bug. For some reason the
system will not acquire signal on the second cup sometimes. If this happens
in a run without peak centering you just get a dead 29 trace (or whatever
you are monitoring in #2), though you will still get a 28/29 ratio plot.
Subsequent runs are always OK. If you are doing peak centering the system
will hang as you describe because it found no signal at all on cup 2, and
then continue on with the run after you clear the error. Look in the
ISOGEOCHEM archives for the subject - Delta plus losing signal in only one
cup for only one run, dated Feb 28, 2002.

PS - no need to SHOUT (using all caps), unless you are stuck on a VAX VMS
mainframe or something. Then shout all you want.

Howard



Howard Sanford
919-513-3039
North Carolina State University
Dept. of Soil Science
Box 7619
3114 Williams Hall
Raleigh, NC 27695
http://www.soil.ncsu.edu/services/sims/