Chromatography Forum

Has anyone come across an Entrance Lens voltage of zero upon autotune?
5973 MSD.
It's not a consistent thing but happens enough to question what the cause may be. 69 will be about half of normal abundance when this happens with 219 double it's normal abundance. You get 300 percent 219 relative to 69 at some times with this combination.
If I can remember correctly I believe I've tried another copy of atune with no change in results thinking it was software related.
Any ideas are appreciated. Faulty wire to the entrance lens pin? I have two machines that this happens to. They run the same analysis and take a lot maintenance. Faulty wire somewhere?
Thank you.

I normally use a BFB tune and on my 5975 the entrance lens voltage is normally zero. I haven't checked my 5973, but I expect that it is similar.

I also see the entrance lens at 0. I usualy do a BFB tune as well.

Thanks for the information.
I limited the repeller voltage to 25 and was able to get a 219 abundance of 113. The ion focus came in at 63 not zero as it had previously.

I tried this on another instrument and it did not seem to "reset" anything. 219 is 256 relative to 69. The entrance is at 0.

You could just adjust it by hand by ramping the repeller and lenses, then adjust each to achieve a tune. I have done that many times when an instrument is having trouble tuning by the automated parameters in the computer.

I Have come across an Entrance Lens voltage of zero upon autotune.

Did you open the MSD?

If the entrance lens is 0, that can be because of the wire or its pin is in contact with the body of the ion source.

Check that

I'm replacing the lens insulators just in case and will see if that helps.
That came to someone else's mind when I mentioned the zero voltage.
Thank you.