K4900 color problem, post tube/yoke swap

pepind

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Hi everyone.

I'm having some trouble with a Wells 4900 that I was tube swapping (due to burn). I'm using a 19 in 1 board for my test pattern and whatnot.

Its probably easiest to let the pictures show the problem, but in a nutshell, the left side of the screen displays proper color, but as you go to the right, the colors are wrong (and yes, I've tried degaussing with a proper degaussing coil).

The old tube did not have this problem. I had one other CR-23 tube from a different donor TV, that I had thrown on a G07 and worked fine (aside from it having a bad horizontal width coil, but that's a different story...) and swapped that tube in, and same results.

The chassis has been recapped (and was running with the old tube). Is it possible I screwed up something with the yoke windings when swapping around? I wouldn't think that would affect the colors so much as the shape of the picture, but I'm trying to figure out the common denominator.

Is this maybe just a coincidence and something on the chassis is failing? I have a spare (supposedly working) complete chassis I could toss in there, but want to eliminate the rest as a problem before putting it in.

Thanks for any help!
 

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looks like you need to adjust the yoke for purity.

center all the pots on the neck board.
put it on the solid red screen in the test patterns.

adjust the yoke back or forward on the neck till it is pure red.
degauss as you do this.

then after you have the red set tighten down the yoke some and return to the grid with all colors and adjust with the neck pots.

Peace
Buffett
 
Thanks Buffet!

That was the problem. I had just slapped the yoke on and straightened the picture, without really positioning it properly. Also, I had to move the cabinet in the room, as it was also having a gaussing problem. Went through the same thing with a Moon Cresta cocktail that I used to have...
 
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