Charlotte Lehmann a écrit :

> At Gilles and others suggestion, I checked to see if the amplifiers  
> were zeroes with the source off. they were/are. I ran the amplifier  
> test in the diagnostics program and came back with zeroes, but it was  
> only finding one gas configuration (CO) not all of them (N2 and CO2  
> being left out).
> Then I tried a mass calibration as Sergey suggested. The mass  
> calibration cannot be completed because instead of shifting the mass  
> 44 BDAC value to a lower magnet field (from start at 11637) as it is  
> supposed to (and does for masses 12 and 28), it shifts to a higher  
> magnet field (19595) after the second cycle and then cannot find the  
> peak on the third cycle.
> We have a newly installed (in June and July) Delta V Advantage 
> running  with Isodat 2.5.
> Any more suggestions or do I need to call in the Thermo service  
> engineer? It is under warranty afterall!

dear charlotte,
I don't know what  the values of your resistance and capcities of your 
amplifiers are.  If thare are the same order try to swap  them : 44 on 
45 and 45 on 44 and look to your background. You can  gently clean them 
at the  same time
Best regards

-- 
Dominique Blamart
LSCE/IPSL, Laboratoire CEA-CNRS-UVSQ 
Domaine du CNRS 
Bât. 12, Avenue de la Terrasse 
91198 Gif sur Yvette 
France 

Tel nat : 01 69 82 43 25
Tel int : 33 1 69 82 43 25
Fax : 33 1 69 82 35 68