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We had such an issue after replacing the source recently. It turned out we had connected one of the feedthroughs to the wrong pin on the ion source. If multiple connections get dislodged simultaneously they can be easily confused. This would visually appear like everything was connected, wouldn't raise any red flags with the multimeter, and would generate no signal. Have you checked both the numbers on either side of the feedthrough and whether they connect to the appropriate pins?

Keiran A. Swart
Sigman Lab (Doctoral Student)
Department of Geosciences
A15 Guyot Hall
Princeton University, NJ, USA



From: Stable Isotope Geochemistry [[log in to unmask]] on behalf of Lambert, Joe [[log in to unmask]]
Sent: Wednesday, July 25, 2018 2:25 PM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Fwd: Signal Loss on Delta Plus XL

For what it is worth, two recent filaments from Thermo gave us much less sensitivity on our Delta Plus.  CO2 from the Gasbench  once provided >4000 mV…now we can’t get over 2300 mV.  Still trying to figure out exactly what caused the change…


On Jul 25, 2018, at 1:09 PM, Wolfram Meier-Augenstein (pals) <[log in to unmask]> wrote:

 
Here’s another thought. Are you 100% sure the new filament you got delivered is the correct filament for your Delta plus XL?
 
This happened to me once. Not on a Delta plus XP but another IRMS in the Delta family.  If memory serves the replacement filament was actually for a MAT 253 which, even though physically intact, was dead like a Dodo in our instrument.
 
 
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Getachew Agmuas
Sent: 25 July 2018 16:06
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Fwd: Signal Loss on Delta Plus XL
 
Hello Wolfram 
 
Yes, we did, it is fine, no short circuit. 

 
Best regards 
Getachew A. Adnew 
-----------------------------------------------------------------------------------
Getachew A. Adnew 
PhD student                  
email: [log in to unmask]
Institute for Marine and Atmospheric Research Utrecht (IMAU)
Princetonplein 5
Utrecht University
3584CC Utrecht, The Netherlands
Phone: (+31)-30-2531555
 
On Wed, Jul 25, 2018 at 3:38 PM, Wolfram Meier-Augenstein (pals) <[log in to unmask]> wrote:
Have you checked for short circuits between all source pins (connectors) once the source was installed using a multi-meter set to continuity testing (audible signal)?
 
Sometimes everything checks fine while the source is still outside but the moment it gets installed and the springs get compressed wires inside the source that previously were free may now touch each other.
 
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Getachew Agmuas
Sent: 25 July 2018 14:24

To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Fwd: Signal Loss on Delta Plus XL
 
Hello Wolfram
 
The problem is no signal at all. Thanks, it is a nice tip how to put back the ion source after changing the filament. 

 
Best regards 
Getachew A. Adnew 
-----------------------------------------------------------------------------------
Getachew A. Adnew 
PhD student                  
email: [log in to unmask]
Institute for Marine and Atmospheric Research Utrecht (IMAU)
Princetonplein 5
Utrecht University
3584CC Utrecht, The Netherlands
Phone: (+31)-30-2531555
 
On Wed, Jul 25, 2018 at 2:59 PM, Wolfram Meier-Augenstein (pals) <[log in to unmask]> wrote:
 
If the problem is a lower signal than before / expected, sometimes a tiny “misalignment” of the source flange can drastically reduce material gas flow into the source and thus result in significant reduction in signal while all checks return a clean bill of health.
 
The holes in the source flange and the source housing have to be perfectly aligned. A partial eclipse will result an “almond”  shaped hole.  Despite the guide pin (gun sight) and the matching cut-out there is enough wiggle room for this to happen.
 
Once the source is inserted twist (turn) the flange clock-wise as far as it will go, mark this position with felt pen. Now turn counter-clock-wise as far as it will and mark this position.  Turn back clock-wise until midpoint between these two marks.
 
 
And now for a word from Capt’n Obvious.  Always check all pins on the source with a multi-meter for any shorts once the source has been inserted and all bolts tightened (but before switching on). ;-)
 
 
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of C. Julie Luyt
Sent: 25 July 2018 12:40
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Fwd: Signal Loss on Delta Plus XL
 
Seems this is a common problem! 
 

We have had a problem with low sensitivity on our Delta XP PLUS since our last filament (cathode) change.  As an example, we used to get a voltage on the CO2 reference gas of about 1300mV but now we only get 800mV.  As its affecting both gas bench and Dual inlet, it has to be a problem with an area that is common to both.   It affecting all of the gases:  CO2, O, H. 

 

We have considered the following:

      1.       Faulty filament - changed to another but no improvement (Bjoern suggested an incorrect part, but we checked part number)

      2.       Source - we have removed source, cleaned it and found a cracked ceramic spacer, replaced ceramic-  resulted in a small improvement , but not back to original sensitivity.

      3.       Problem with changeover valve  - took this apart, nothing obvious wrong with it.

     4.    We thought maybe the focus was out - initially we had no signal but we manually focused the machine to find it again and also adjusted the magnets,  and then did an auto focus once we found the signal.

 

      Nothing brought the sensitivity back to the level it was before. 

 

Has anyone had a similar problem and was able to correct it? 

 

 

 


On Jul 25, 2018, at 01:19 PM, Getachew Agmuas <[log in to unmask]> wrote:

Dear all 
 
Our Delta Plus XL is still not working, we did not find any signal so far (we tried both for CO2 and O2). We looked the possible reasons so far, but still we did not solve it. Things we checked:- 
- we changed the broken  filament
- we did amplifier test, works fine
- The Magnet current control board works fine 
- The fuse for the high voltage board works fine 
- connection wires inside the Teflon block on the front of the source

 

Finally, we changed the filament again even if it is not broken, but it does not help. 

 

Any suggestion and feedback is well come.

 
Best regards 
Getachew A. Adnew 
-----------------------------------------------------------------------------------
Getachew A. Adnew 
PhD student                  
email: [log in to unmask]
Institute for Marine and Atmospheric Research Utrecht (IMAU)
Princetonplein 5
Utrecht University
3584CC Utrecht, The Netherlands

Phone: (+31)-30-2531555

 

---------- Forwarded message ----------
From: Getachew Agmuas <[log in to unmask]>
Date: Sat, Jul 21, 2018 at 3:11 PM
Subject: Signal Loss on Delta Plus XL
To: Stable Isotope Geochemistry <[log in to unmask]>

Dear all 
 
After I changed a broken filament, I could not find signal signal any more. I opened the ion source and  checked the filament looks fine. I tried to play with the focusing but there is no luck. Does any body have any idea or suggestion what to do?   
 
Best regards 
Getachew A. Adnew 
-----------------------------------------------------------------------------------
Getachew A. Adnew 
PhD student                  
email: [log in to unmask]
Institute for Marine and Atmospheric Research Utrecht (IMAU)
Princetonplein 5
Utrecht University
3584CC Utrecht, The Netherlands

Phone: (+31)-30-2531555

 
 

 


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