WG 7500 Yellow Tint

ArcadeGeek

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I just picked up a Carnival King with a WG 7500 25". The display has a yellow tint to it that I that I can't seem to adjust out. Will a cap kit fix it or is this a sign of something else going wrong with the monitor?
 
means your red drive is out. either a transistor/resistor issue on the neckboard or the red gun on the tube is shot.
 
yeah, though if that's the case then it's very likely you have a tube issue. :(

as frequently discussed on KLOV, whenever a K7500 topic arises, it's common knowledge that the tubes are either pretty good or they're prone to turning to shit quick. lol I had one that had a red tint and a weak green. but yeah, I would think if you have a yellow tint, it means your blue and green (together) are too strong, or the red is completely absent.

there's a method for adjusting the white balance on the K7500, and following Wells-Gardners instructions on how to do it will result in a near-aneurysm.

if I'm not mistaken though, the first step is to turn your Red and Green Drives (the 2 pots on the left of the neckboard), along with both the Brightness and Contrast pots to their middle position, and turn all the Red, Green and Blue Bias pots all the way down.

make sure that your game/monitor are on for at least 20 minutes (for sufficient warm-up) with the video signal connector unplugged.

from there, on the flyback, turn the Screen adjustment up high enough to where you get a faint bluish grey screen (at least on the U5000 I worked on the "default" color was blue). then turn your Contrast down slightly below the halfway point and then adjust your Red, Green and Blue Bias controls accordingly until you get the best white.

if at this point you're unable to adjust the yellow tint out then you're probably looking at a tube issue. but... if you wish to continue ... :)

then turn the Contrast adjustment a little bit past the halfway point (you'll know if you've gone too far if the colors start to blow out or you see retrace lines... if that's the case then you could try dialing the Screen adjustment back down and re-doing the steps of adjusting the Red, Green and Blue Bias controls with the Contrast turned below the halfway point.) and adjust your Red and Green Drive controls accordingly in the high contrast portion to get the best white.

by doing this, you should have good whites whether the contrast is turned low or high. you can reconnect your video signal cable at this point, and see how the game looks. if you have good white balance with NO video signal connected, but the yellow tint returns when you hook the game back up to it, then you probably have an intermittent connection on one of the JAMMA pins, which I've seen happen a few times.

after you do all this, turn your Brightness and Contrast up, and then back off on the Brightness until the black background shows up black, and back off the Contrast until your text/colors no longer smear.

hope this helps.
 
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