I have a Dell UltraScan P990 which has drifted out of focus over the last 8 years. I know that sudden or drastic focus drift is a sign of something failing, but this had been a very gradual drift over many many years and really isn't all that bad, just enough to be a pain. This monitor has been used for a few hours every day for the last 8 years, (I'm sure there isn't much life left in the tube), so I assume in this case it is considered acceptable to re-adjust the focus?
Which brings me to my question. The monitor has four access holes on the back left side for adjustment. Two appear to go nowhere, the other two go to the two adjustments on the flyback. I however can't tell exactly which is which, as it is dusty, behing shield, etc.. and I really don't want to open this one up. Focus is written between the two adjustment pots. The bottom definantely has a 2 beneath it. I can't tell if the top has a 1 above it. I've seen flybacks with both screen and focus, or screen and two focus, but not just two focus (I'm sure they probably exist, I have little CRT experience). I suppose it is possible there is a third that is below the holes that I can't see. Anyway, does anyone know if these are both focus adjustments, or if not, which is focus? I don't want to accidentally adjust the screen level.
And, sort of off topic, I know that if you adjust the Anode too high, the possibility of generating X-Rays can become an issue. Does adjusting Screen have any safety effect like this, or can it just reduce tube life if too high?