Inlet pressure shutdown...then tuning doesn't work?!

[wenleonard]

I have a 7890a/5975c GCMS system that has been running like a peach, when the inlet pressure started becoming unstable and ended in an inlet pressure shutdown. I replaced the liner, o-ring, and septum and was able to get pressure back. However when I went to perform an air and water check it failed halfway through and gave me an error message "cannot achieve constant peak widths". I cannot tune at all and when I look at the profile the masses are all over the place.

The source was recently cleaned so I don't think that is an issue, and the response is the same on either filament, which were just recently changed.

I changed the column nut/ ferrules on both sides of the column and will see if I can tune after that.

My concern is that it is something electronic in nature, maybe the front board has a short.

If anyone can help I would appreciate the advice!

[James_Ball]

I have a 7890a/5975c GCMS system that has been running like a peach, when the inlet pressure started becoming unstable and ended in an inlet pressure shutdown. I replaced the liner, o-ring, and septum and was able to get pressure back. However when I went to perform an air and water check it failed halfway through and gave me an error message "cannot achieve constant peak widths". I cannot tune at all and when I look at the profile the masses are all over the place.

The source was recently cleaned so I don't think that is an issue, and the response is the same on either filament, which were just recently changed.

I changed the column nut/ ferrules on both sides of the column and will see if I can tune after that.

My concern is that it is something electronic in nature, maybe the front board has a short.

If anyone can help I would appreciate the advice!

If the leak caused damage to the column stationary phase it could have baked off onto the source if it was heated up. This would cause stability problems. Also if there is still a leak, but small enough that you don't get a front inlet shutdown, the air could still be causing problems with tuning.