K7000 brightness issue

LyonsArcade

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Hi guys;
I have a Lethal Enforcers cabinet with an Area 51 kit in it. The monitor is a huge 25" K7000, it's one of the ones with the special flyback that's commonly used on shooting games.

Anyways, the top of the screen is brighter than the bottom. This is a horizontally mounted monitor, and the monitor has a mirror, so it's actually the bottom of the TUBE that is brighter. If you were looking at it without the mirror, the bottom of the monitor (away from the anode) would be the bright part. There's a perfect gradiant from light to darker on the other half. It almost looks like it's designed that way, except I don't believe it is LOL.

I did a capkit with no change. Anybody have any ideas? Is that thing on the flyback likely my problem? can any of this be adjusted?

Thanks
 
If this was a K4900/K5500, I'd tell you what cap to check.

Obviously, go over your work.

As far as the brightener, I've not seen one cause this problem before, but I couldn't tell you for sure whether this is your problem. Unless you have another to swap in, I don't know what to tell you.

Can you post a pic of it?
 
K7000 pics

Mod, here's some pics. I turned the brightness up to exagerate the problem so you could see it better, so nevermind the bleariness... you can kind of make out what I'm talking about though, the top of the image is much brighter than the bottom, and it's almost a perfect gradient. I've seen monitors do this side to side and a cap would fix it, but this is kind of crazy.

Would I be safe to say it's probably in the vertical section? I could go through and start checking resistors and things I guess. The brightner thing you're talking about, the more I think of it I don't think there's anyway it could do this, because it would effect everything, not different on the top or bottom, would it?

Keep in mind too you're looking through a mirror, so the bright part is actually the bottom of the tube, if that makes a difference.

I looked over all my caps, and everything looks right. It was doing this before and after the capkit.
 

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Hard to tell, but it looks a bit from your middle pic that you may have foldover, which sometimes makes the top of the screen look a bit brighter. Try reducing the vertical height and see if it goes away.
 
you need to tirn down most of the color gains and cutoffs untill that "bleeding" goes away.. they retry to readjust.

Its too bad your not local, i suspect a weak tube..
 
I can trim it all down, and did, but when I do that, the bottom of the image is much much darker than the top (i.e., black). I turned the brightness up so it would show up better in the picture. It doesn't have foldover, either.

How could it be the tube? If it was the tube, wouldn't the entire image be bad? This is like a perfect gradient from one side to the other.
 
Well, it was a really strange problem... believe it or not, I think it was just the ground wire going from the board to the remote board had broken. Pin 11 I believe, the black wire that ties in around the horizontal hold section on the main board. The ground wire there connects to the horizontal position, vertical position, brightness, and another pot on the remote board. Apparently with that free floating, it somehow ties the brightness into the vertical position or something, and makes the top of the screen bright, and the bottom dark.

Found the wire broken when I pulled the board out, resoldered it and a couple other shaky ones and now it looks perfect.


Thanks for your help guys!
 
Yeah, add away, that's why I posted the resolution to help other people (and me after I forget what the hell happened and go searching for it, lol)
 
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