Discussion Category:  GC-Single Quad/MSD

Agilent 5973N signal loss

Good Evening !

Well, not so good here... I am stuck with an EMERGENCY trying to figure out why my MS just stopped working.

Was running a basic DFTPP, Cal Check to start a run batch and when I returned the samples had been running and stopped collecting any data... just a bunch of noise.  Thinking went to manual tune and chenged my filiment thinking I might have an issue there... same issue.  I vented the system and checked my source and it was relatively clean and the filiments were intact.  I chenged the filiments just to be safe and put everything back together.

I ran a manual tune and I am get basic scans, but the repellervoltage keeps fluxuating.. I m going to replace the Repeller insulator and check all of the connecting but I am thinking I have a bigger issue here.  This instrument went from working very well non-operational.  

I an't think of anything else off the top of my head unless there is an issue with the EM... The source is in great shape.   My other instrument is down and I have been to swamped to even go through the suggestions posted.

Help !

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Asked by

RalphB
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Dan Ste.MarieReply by
Dan Ste.Marie
Ralph, Two things come to mind. First verify that the column is not sticking out too far, if itis it will block the ion path and you will not see any peaks. Second is the repelled set to cramped? Dan

Dan Ste.Marie

RJ2 Instrument Services

Erie, PA

www.rj2.biz

   
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RalphB

Hi Dan,

I vented again last night... I replaced the repeller insulators and made sure there was no dirt. I am so checked the column depth while I was in there, All looked normal.

I let it pump down over night and am getting ready to see if that helped

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avatar placemarkReply by
RalphB

The EM Voltage is high... Is it possible that this is an EM problem ?  Ramping my repeller and it looks terible.  Sorry, I'm grasping at straws

 

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sharpie

Ralph,  are you certain you have the basics covered ?  Good  Vacuum in the ion source (not just mTorr readings in the rough pump hose), no big air leaks, helium flow, calbration valve opening, etc.... 


Scott Niemann

CSS Analytical Co Inc.

www.cssco.com 

800-277-5455  
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RalphB

Hi Scott,

Yes, went through them twice... only thing that changed from a Good run the prior day was a simple Cut n Clean.  Then is was haywire... Detector side was not changed at all... at 46mTorr.  

Rough pump hasn't been toughed since last basic maint. oil change 3 months ago... levels fine.

Put on a new Cylinder of He, just in case bad Cylinder... No Diff.

Redid injector port again just to be safe... no change.

Vented and did MS maint. and Changed Filaments, Put in new column... FULL... No Change.

After Auttune... Im getting some signal, but my EM is high...218 and 501 are very noisey... Repeler is maxed and Ion Focus maxed.

I'm thinking of changing the EM next... ater that it comes down to boards.

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Dan Ste.MarieReply by
Dan Ste.Marie
Ralph, What do you mean by High what is where did the EM. end up after Auto-Tune.

Dan Ste.Marie

RJ2 Instrument Services

Erie, PA

www.rj2.biz

   
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RalphB

Hi Dan,

 

Normally (meaning my last good tune) my EM was at 1860... EM since this happened have ranged from 2400 to 2600 though I did get it to 2084 after the recleaning of the source.

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sharpie

Ralph,  I asked what was the actual Ion Source pressure - In Torr.  Not the mTorr pressure of the rough pump hose.  It's important that you have good vacuum in the ion source area (manifold area) which can only be measured with a ion gauge tube and Ion gauge controller.  The vacuum should be in the mid 10E-5 Torr range. Otherwise you will not get good ion creation and transmission and also sparks can jump from hi voltage wires to many places you don't want it to. Relying on the mTorr reading of the rough pump "zone" is fine for day-to-day operation, but when you are trouble shooting a difficulty  MTorr readings  ARE NOT sufficient.  


Scott Niemann

CSS Analytical Co Inc.

www.cssco.com 

800-277-5455  
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Dan Ste.MarieReply by
Dan Ste.Marie

Ralph,

I have to agree with Scott in that based on the behavior of the EM and the scan results you described, I think that you have a significant leak in the system.  Even though you are at 46 mTorr for the rough vacuum, your high vacuum might not be low enough.  Did you run an air/water check prior to tuning and if so what were the results?  Make sure when asked if you want to use standard conditions you reply yes.

For the EM to jump 600v tells me that the autotune is compensating for lack of response (which can be due to a variety of issues)  as opposed to the EM being "bad".  I am going to guess you do not have an ion gauge hooked up to this system.

Dan


Dan Ste.Marie

RJ2 Instrument Services

Erie, PA

www.rj2.biz

   
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Dan Ste.MarieReply by
Dan Ste.Marie

Ralph,

I have to agree with Scott that you cannot reply on the rough vacuum of 46 mTorr as being a reliable indicator that you have sufficient high vacuum for the system to operate relably.  I am guessing that you do not have an ion gauge monitor hooked up to the system.

The behavior of the EM voltage when tuning indicates to me that you have a significant leak even though you have an acceptable rough vacuum.  Did you run an air/water check prior to tuning and if so what were the results?  The 28/69 ratio should be less than 10% to operate and typically will drop to less than 2-4% when pumped down overnight.  A jumo of ~600v in the EM voltage when tuning after maintenance is a good indicator that a leak/insufficient vacuum is present.

Dan


Dan Ste.Marie

RJ2 Instrument Services

Erie, PA

www.rj2.biz

   
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