Learn me.. Monitor focus..

foxtrot_xray

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Hey all,
Have an odd question. (I'm always learning..!)

I know that monitors have a 'focus' knob, sure.

But on my 27" screen, while the center of the screen and a radius around the center is in focus, the edges are blurry, with the corners pretty bad.

Does this effect have a name? Is it fixable?
 
It's more of a purity problem than a convergence problem. You will need to adjust the purity to fix something like that...assuming you don't have a bonded yoke.
 
Probably purity. Sounds like maybe you're yoke moved.
 
Interesting - I'm 99% sure the guy that recapped my board did not mess with it, though he did mention he did the convergence. Is adjusting/setting purity the same on EGA vs CGA tubes?

I'll edit to add that the out-of-focus isn't drifting in any color - i.e. the white cross-hatch pattern, the corners are fuzzy, but still white. No R, G, or B hazing.
 
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from personal experiance, the 27" class and above never did focus very well in the corners.

i use 2 27" test tubes here one med res 7502 and a U2000/7400 that has NEVER had the rings or yoke moved, and even with a new flyback the outer edges starting about 5-6 inches from center always are hard to get to focus.

this is the same with new flybacks on the chassis and old flybacks that are still rocking with no problems.

most times you will have to split the difference when adjusting the focus to have a happy medium.

this is not always the case with the 27" class, but is what i find from having 27" monitor games.

you could also get the tube checked with a rejuvinator and see how poor the focus is.

a clean and balance or rejuve may/will also help the tube focus.

if you want to take a road trip, you can bring the monitor here and we can check it out.

Peace
Buffett
 
personal experience: weak tube. also had a monitor once (don't remember which) where a new flyback cleared it up. it was strange. coupling both issues together, I'll say it was the K7500 out of my Sportstation. :) that was a 25" however.

I wonder if the convergence strips would cause this. I've seen 27" tubes where the corners had convergence problems cause there were no strips in that section. focus is essentially moving around convergence kind of right?
 
personal experience: weak tube. also had a monitor once (don't remember which) where a new flyback cleared it up. it was strange. coupling both issues together, I'll say it was the K7500 out of my Sportstation. :) that was a 25" however.

I wonder if the convergence strips would cause this. I've seen 27" tubes where the corners had convergence problems cause there were no strips in that section. focus is essentially moving around convergence kind of right?

Yes and no. To properly adjust it, you need to do the purity too which involves moving the yoke.
 
Thanks guys! Interesting info..!

I know Buffet mentioned this is common for 27" monitors. The one he did for me is fuzzy, but not sickeningly so - not to the effect this one is. The one he did is MUCH better than it was!

(I tried, several times, to get a picture - I was unable to - standing back far enough to get the whole screen in, it was too far away and hard to make out any details.. Zooming in, and all you got was a white blur from the camera being unable to focus. D'oh.)
 
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