Chromatography Forum

I've been having a problem with my 5973 where the repeller voltage keeps reaching max (30 volts) no matter what I do. "atune" checkout fine, but I'm not happy with the ion ratios. "stune" works, but produces a dirty looking 502 peak. The machine produces pretty good results, but I'd like to improve things.

I've cleaned the source more than once, changed filaments, ramped all the source voltages to confirm everything is at least changing, with no results.

Air and water check is pretty good, everything below .5%.

I realized that I used an inert repeller in my non-inert source. Does this matter? There is a shallow divot in the inert repeller that I assume simply identifies the inert part, does the orientation of this matter?

This raises another question: can you use the entrance lens from the 5975 in the 5973? The part numbers work, but the design is somewhat different, in that the "neck" of the entrance lens has a reduced diameter collar.

I've been having a problem with my 5973 where the repeller voltage keeps reaching max (30 volts) no matter what I do. "atune" checkout fine, but I'm not happy with the ion ratios. "stune" works, but produces a dirty looking 502 peak. The machine produces pretty good results, but I'd like to improve things.

I've cleaned the source more than once, changed filaments, ramped all the source voltages to confirm everything is at least changing, with no results.

Air and water check is pretty good, everything below .5%.

I realized that I used an inert repeller in my non-inert source. Does this matter? There is a shallow divot in the inert repeller that I assume simply identifies the inert part, does the orientation of this matter?

This raises another question: can you use the entrance lens from the 5975 in the 5973? The part numbers work, but the design is somewhat different, in that the "neck" of the entrance lens has a reduced diameter collar.

The only thing I think is different is if you get parts from a CI source, otherwise they should be interchangeable. I have even mixed and matched Inert and non-Inter in a pinch. The "dot" on the repeller if it is on the back side of the disk does indicate inert I believe, on the front side it might just be a nick from something hitting it.

If the repeller is maxing out at 30v, what is your emission current setting?

You can lower the peak of the repeller by lowering the emission current most times. If it is 35uA then try lowering it. I run some instruments as low as 19uA with no problem. You drop sensitivity a little over all, but it becomes more biased to higher masses as you lower the current, which might help with the 502 shape.

Thanks. I found an old application note about setting emission current for the 5972. I tried lowering emission from 35 to 30ua and then ramping the repeller. That moved the optimum repeller voltage down a couple of volts.

However, I can't get the change to become the new tune default. As soon as I choose tune, the system defaults back to 35ua. How do I make the change permanent?

My chemstation version is G1701DA D.03.00.611 with patch_02 applied.

I thought there used to be a window where you could set the ranges for each parameter but on E.02 I can't find it. I don't have anything running D version now.

I almost never run the tune macros, only if I have done something major like change the Electron Multiplier or have disturbed the quads such as the slight movement they can get when working on the HED or changing a board. If I do need to run on I use the Atune and from that I manually tune to either BFB or DFTPP if needed, I find I can do that faster than the macro can most times, plus I optimize the repeller vs emission before starting the final mass balance and peak width adjustments.

Normally after a source cleaning or filament change the previous tune is very close and I just need to touch it up a little once it thermally equilibrates overnight.

Of course I began with the 5970 and 5995 on RTEa which only had the standard Atune, everything else required manual tuning so I had lots of practice.