Dell UltraScan P990 Focus Drift

And, from what I can see the flyback has written on it:

Why would you assume that ?

Graham

In some of these models, there are two focus pots, and one for the screen bias. The two pots are for both the H and V axis focus. The screen bias will effect the beam current of the tube.

The poor focus is most likely caused by the age of the tube. Also, it is possible that the high voltage multiplier has drifted out of spec with age and use.

You have nothing to loose by messing around with the adjustments and see where they lead you. Most likely, by the way your description sounds, you will soon be needing to buy a new monitor anyways.

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JANA _____

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?

Thanks, Steve

They are both for focus. One will change mostly the horizontal focus and the other the vertical. You need to alternate between them while looking at a grid pattern. Adjust so that both horizontal and vertical lines are as sharp as possible.

It's common for monitors and TVs to require focus adjustment after a few years. Even new ones are rarely set perfectly from the factory.

These monitors don't have a screen control (it's adjusted with software). Andy Cuffe

snipped-for-privacy@gmail.com

It's my understanding that CRT's have an average lifespan of approximately 10000 hours. When I was in college, the screen was on at least 6 hours a day for four years, and after that it's been on for at least 4 hours a day, I bought it in 1999, so ~14500 hours. Plus, the tube has started to slowly fade. I could of course be wrong in my assumption, it just seems that frequently used monitors don't normally last 8 years, and if they do the tube probably doesn't have much life left in it.

Steve

Thanks so much, adjusted them both and it looks nice and crisp again.

Thanks, Steve