Dear Isogeochemers,


Not really a real question rather than a story I feel is worth sharing.


We have two Delta Plus XPs – both the same age – that both had issues with the ion source control board recently. Symptoms were loss of HV to ~0.34 and consequently weird or no signal on the detectors. We were fumbling around for a while and eventually Thermo suggested replacement of both control boards. Because this is a very pricy fix, and both machines are past warranty, we decided to try repairing the boards with our inhouse electrician as a last ditch effort.


According to the veterans in here, the symptoms we’ve observed are related to faulty capacitors on the control board. We replaced all 4 of the blue ceramic capacitors that are rated at 4nF (labelled 4n7S 3kV) on both boards, namely C203, C206, C231 and C703. We didn’t even have to remove the board completely to do so and the whole operation was done in about 2-3 hours. HV is now back up and we have nice and clean signal on both machines. Linearity/precision do not appear to have suffered. So THANKS to everybody for keeping this list going – it saves a lot of trouble and money.


Now what worries me about this story: Apparently the exact same issue occurred on both Delta XPs within 2 weeks or so. Our Delta Vs were running smoothly. Does this maybe have to do with our inhouse power supply? I generally try to avoid conspiracy theories, but the word ‘planned obsolescence’ come to mind.


Any thoughts on this?


Merry Christmas,



Paul Töchterle, MSc

Stable Isotopes Engineer
Karlsruhe Istitute of Technology (KIT), Campus Alpin
Institute of Meteorology and Climate Research (IMK-IFU)
Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen (Germany)
Tel: +49 (0) 8821 183 163
[log in to unmask]