This is my first post and I'm excited to have discussions for this thread.
I wanted to start off with a small introduction with some of my experience. I have 4 years of experience in operation, maintenance, method development on the following systems: Agilent GC 7890 triple quad, Waters Xevo TQS LC-MSMS, Agilent ICPMS 7700x and 7500, GBC AAS and Waters HPLC.
In my new position I have inherited an old HP 5890 GC-FID (older than I am). Fairly obvious that I will not have software control over conditions and measurements. (Hell, my ChemStation software shut-down program doesn't work).
I have been operating for 6 months now with not too much trouble and have been releasing test results of samples. I recently have been receiving an EPPA Shutdown Error. This is similar to other posts I have seen for various GC models. I was able to get off Injections prior to the error shutting down the system and once I began my sequence the alarm went away. Eventually, the time of alarm got worse and worse.
Long story short, I figured out that EPPA was not a random error code, but referencing the pressure of Inlet "A". So I did some injections and watched the pressure which after a while if it doesn't reach the set point will shut down the instrument. I noticed that someone had changed my carrier gas cylinder tank, so the inlet system/column was not receiving sufficient gas to operate (Fairly simple).
I increased the gas flow to slightly above 50psi with the regulator and the alarm went away. The next day, I came into run my system check and noticed an extreme drop in signal (both analyte and baseline). I have lost my higher level standards signal (almost looking like a ******* beers law past 1). Additionally, my resolution is ****. I have multiple peaks forming one full peak at higher concentrations.
My hypothesis and plan moving forward: I assume the poor resolution is due to the inlet septa. So I'm going to replace the septa and liner. Then take some measurements of column flow/FID gas flows (hydrogen/air). To be honest, it wouldn't surprise me if the Jet needed replacement (I think the igniter isn't responding well either). My guess is that this instrument was neglected for years.
Anyways, pleasure meeting you all. Sorry for taking so long to meetup. (I will post or PM anyone who cares to see pics)