wg4900 horizontal distortion in 48-in-1

cwstrong

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Hopefully someone can help me with this monitor issue that's been driving me crazy!

I've swapped a wg4900 tube and chassis from a Street Fighter II into a 48-in-1 cab. I've performed a cap kit and added a new horizontal width coil from Bob Roberts due to the inability to increase the horizontal width on the monitor. Once the new coil was installed I noticed what appears to be a horizontal pincushioning that I cannot remove. The screen will not stretch the entire length of the screen without being distorted towards the bottom of the screen (monitor is vertical in cab).

I've adjusted all pots on the chassis as well as the jumpers on the vertical and horizontal raster shift pins, but no change. I also seem to have a issue with the vertical centering of the screen. I can only adjust vertical positioning in one direction, which leaves the screen slightly offset to the right.

This is driving me nuts....any ideas or advice on how to fix these issues?

Thanks in advance!
 
1) If you are trying to expand the screen horizontally (up and down on the vertically mounted tube) and can't do so with the horizontal width coil, you need to do this:

http://therealbobroberts.net/width.html

2) Your Horiz Hold pot (located behind the other pots on the left) should help square up the picture. Once you have it square, adjust the width as mentioned above.

3) If you are for some reason referring to the vertical width (left and right when mounted vertically), there are some early versions of the K4900 that didn't come with a Vertical Linearity pot. These must match a specific yoke and will have foldover problems that can't be adjust out if they are paired with the wrong yoke.

4) As for shifting the image, sometimes it just won't change enough. You probably could get it closer by adjusting the centering rings on the neck, but you might end up messing up the convergence rings at the same time, making it more trouble than it's worth...
 
Much better!

I swapped out the C365 width cap with a few I had from Bob Roberts until I found one that was adequate. I also adjusted the centering rings...carefully...and did get the picture to become centered. Additional pot adjustments did help alleviate the pincushion distortions.

Thanks for confirming my options and leading me in the right direction, modessitt!

Now I just need another pair of eyes to help me do some final tweaking.
 
Glad you got it better. Too many folks tend to just say "Multigame boards do this with certain monitors and you can't do anything about it". In my experience, I haven't found a specific model that can't be pretty good through proper adjustments and parts...
 
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