Tech Help Needed -- K4900 Slight Horizontal "Pin Cushion"

Anthony605

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I have a K4900 that has a super slight horizontal "Pin Cushion". It is so slight that I do not think it will be noticeable if I try and take a picture of it. The best way to describe it is if there is a perfect square (like in Robotron), the left and right side borders and bent very slightly inwards. Is there an adjustment for this or a potential fix? I will try to take a picture of it. Thanks in advance for the help!!
 
Here is the best pic I can get. The Robotron border that the orange arrow points to is bent slightly inwards.
 

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If a cap kit doesn't fix it, then I personally wouldn't worry about it. I can't even see the issue even though you have an arrow pointing right at it.
 
LOL. Yeah it is very slight. Here is a "better" pic from when I run Joust through the JROK. As you can see, the border is very very slightly bowed in.
 

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Hey Pat! It was recently capped. I didn't cap it though so I don't know where the kit came from. They do look like Nichicon though.
 
I've seen this on a few 4900s, both in a vertical mount and horizontal. It seems to be a fairly common characteristic with one side (namely the horizontal right side). The only way to correct that (that I know of) is to use magnets on the tube itself -- if you're willing to spend a chunk of time with trial and error. Once the geometry is where you want it, you'll probably have to correct the corner convergence with one or more strips. I've done this a few times and it definitely works, but you really have to have some serious OCD (like I do) and extreme patience lol.

If it were a 4600 or G07, you could correct it by simply by adding one or more small magnets on the side pin cushion transformer. But sadly, to my knowledge, the 4900s don't have side pin cushion transformers. I made a video demonstrating this a few years back.


It's interesting that some of these monitors have their own geometric characteristics. For example, nearly every K7000 I've seen, has an ever so slight dip on the vertical top part of the image.

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I've often thought about experimenting with different value caps, if I (or one of the K7000 experts) could figure out which cap(s) affect that area. It'd be interesting to see if it could be corrected.
 
I will probably just leave it as it is. The colors are really nice and the "bend" is ever so slight. Like @tron guy said, I will likely make it much worse. @jimbodeanny , I will take a look at your video in a bit. Thank you guys very much! Its appreciated. The monitor is from my Sinistar and is going back into Sinistar. Therefore, I do not even think that the bend will even be noticed. It is just my OCD!!
 
I will probably just leave it as it is. The colors are really nice and the "bend" is ever so slight. Like @tron guy said, I will likely make it much worse. @jimbodeanny , I will take a look at your video in a bit. Thank you guys very much! Its appreciated. The monitor is from my Sinistar and is going back into Sinistar. Therefore, I do not even think that the bend will even be noticed. It is just my OCD!!
I didnt wanna say you're being OCD so I'm glad you said it.
 
you are a magician with magnets. every time I try them it makes the picture MUCH worse, and way more distorted.

😆 hah - yeah it's definitely a painstaking process of trial & error (that I usually spend hours on), but it does work. It always depends on the game and whether or not it's worth it. Many games don't benefit from it because you can just adjust it out. But if it's a game that has text or other vital info on the far edges of the image, it can be much more annoying and noticeable. For example, I've done this with the lower Sanyo monitor on my Super Punch-Out (where there was bowing at the top, just like a K7000, causing the knockout meter to droop/bow down). There have only been a handful of times that I've went through it honestly - maybe 3-4 times. The majority of the time, it's unnecessary, especially for the time investment.
 
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