Hello All, I am having a bit of an issue with my Sercon 20-20. It turns 23 years of age this month so I fully appreciate that it may have a few 'quirks' by now. After having issues with the focus amongst many other issues I have changed the source board, the digital board and the adapter board in the last month or so and I still have an issue with the ion repeller. When set at '0' I get a set point reading of '6.77' and an actual of '16.54', I changed the setting in the software to '-2' and the set points and actuals did not change. I have checked for continuity within the source itself and from the source board to the source and there is no issue. I am at a loose end now...help me...any ideas? Luke Harrold Research Technician Soil Isotope Group Office: G09 Labs: G.01,G.05 and G.34 School of Biological Sciences, Cruickshank Building, University of Aberdeen, St Machar Drive, Aberdeen AB24 3UU [cid:[log in to unmask]] The University of Aberdeen is a charity registered in Scotland, No SC013683. Tha Oilthigh Obar Dheathain na charthannas cl?raichte ann an Alba, ?ir. SC013683.