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Discussion Starter #1
My picture has too much red on the right and left sides of the screen and is ok in the middle. On a single tube system I would have adjusted purity, but I don't know what to do on this one. The service manual refers to "centering magnets" on the picture tube yokes, and there is no reference in the manual to "purity" anyway. Any suggestions, anyone? I've set the screens, cutoff, and drive levels and I can't seem to achieve good balance with the reds. The sides are always brighter, and it's as if the screen was divided into thirds, with the edges being too red and the center being balanced.:gah:
 

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Is it a convergence problem or a color shift? How are you evaluating it?
 

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Discussion Starter #4
It's not a convergence issue. If you look at a picture with lots of white background, you see the screen apparently divided into 3 vertical sections. On the left it's predominantly red, the middle looks normal, and the right looks predominantly red again. I wish I could post a picture. Imagine the electron beam that is being 'painted' on the phosphor of the picture tube as it scans from left to right. It starts out intense, and about 30% into the scan it loses intensity as if someone turned the gain way down in mid-scan, then it stays at that intensity until the beam gets to about 60% into the scan, when the intensity comes back up to where it started out, and finishes off the scan to the right of the picture. Then it starts all over again at the left side of the screen and repeats. The result is that it looks like there are vertical stripes of red that are painted on the left and right sides of the screen, top to bottom, that start at the edge looking just as if the screen G2 adjustment were too high, then going to a normal picture in the middle, and returning to high again on the right. I hope I'm doing ok describing it. Like I said, it would be cool to be able to post a picture...any ideas?
 

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You could have a g2 problem. These sets act funny with g2 adjustments that are off. More likely would be something in the scan velocity modulation where your edge focus is off. These kinds of problems can get messy to figure out. I have no easy solutions for your problem. It would take closer examination and troubleshooting. First thing to do is put up a cross hatch or dot pattern and check the edge focus vs the center.
 

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Discussion Starter #6
I was afraid that might be the case. I'll get out my old cross hatch generator and check it when I get back from work tonight. I remember a leaky capacitor doing something like this, long ago and far, far away. I've got a nice ESR meter that might earn it's worth here, also a Hewlett-Packard 4260A universal bridge if I really need it...
I'll report back as time allows. Thanks.
 
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