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Hi Patrick,

Thank you for your quick response! Where is the magnet control regulator located?

Wei Huang

> On Jul 23, 2019, at 5:27 PM, Patrick Griffin <[log in to unmask]> wrote:
> 
> A noisy H signal with a (mostly) stable CO2 signal is consistent with what we have observed when a magnet control regulator is in the process of failing.  
> 
> -patrick
> 
> On Tue, Jul 23, 2019 at 5:10 PM Wei Huang <[log in to unmask]> wrote:
>> Dear all,
>> 
>> Our lab has a trace GC isolink coupled with Thermo Delta V through Conflo IV. Recently, we hav a very noisy D/H ratio trace shown as below. 
>> 
>> 
>> 
>> Once it happened, I cleaned the ion source, replaced the filament and the slit, re-tuned the ion source. But, the problem still exists. 
>> 
>> Also,  we have found that the value of the HV step during the peak center at the start of an acquisition changes dramatically throughout the course of a sequence  - Peak center value could change from 59307 to 60174, no matter with the old filament or the new filament. 
>> 
>> However, we havn't seen significant noises for our CO2 scan so far, or maybe very tiny bit which can be ignored. 
>> 
>> Any suggestions or hints are appreciated! Thank you very much in advance!
>> 
>> 
>> Wei Huang, Ph.D.
>>  
>> Stable Isotope Lab Manager
>> Lamont-Doherty Earth Observatory of Columbia University
>> [log in to unmask]
>>