K4600 Adjustment Help

Vraz

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I have a K4600 in my Defender that has always looked pretty bad (very poor color). I went ahead and used it for my first recap. Post recap, the monitor still works (yeah) but it probably looks slightly worse. Can someone provide some advice on how to adjust the colors. I have looked at the K4600 manual, but it doesn't seem to address this (or at least not in terms that I understand). I have played with the R/B drive to get basic colors. but I don't fundamentally understand what many of the controls are really trying to do (and again, the manual does not seem to explain it in terms that I understand).

Below are a couple pictures from the video test modes in Defender. As you can see, the colors are pretty Appreciate any pointers.

k4600-def2.jpg

k4600-def1.jpg
 
If you're having to turn the red up that high just to see it, then you might not actually be getting any red? If you are have'ng to turn it up that high to see the red, try replace'ng TR206 and TR209 on the main board, and TR401 on the neck... those are the transistors related to red.

Just my 2 cents.
 
If you're having to turn the red up that high just to see it, then you might not actually be getting any red? If you are have'ng to turn it up that high to see the red, try replace'ng TR206 and TR209 on the main board, and TR401 on the neck... those are the transistors related to red.
So I think the overall red tinge was related to the screen and/or black level being off. When I adjust those, I can get a black screen with image. However, all the colors remain muted. If anything, red feels the strongest. All colors (red, green, blue) are present, but none of them (including red) has any real intensity to it. As I turn up brightness to to gain intensity, then I get the red screen hue.

To make sure I am not chasing phantoms, will try to connect the Defender to a known good monitor to validate that its video signal is not the culprit. Assuming that is not the case, then maybe I start with replacing all six color related transistors (TR204-TR209) since they are cheap and the interface board is easy to remove.
 
So I think the overall red tinge was related to the screen and/or black level being off. When I adjust those, I can get a black screen with image. However, all the colors remain muted. If anything, red feels the strongest. All colors (red, green, blue) are present, but none of them (including red) has any real intensity to it. As I turn up brightness to to gain intensity, then I get the red screen hue.

To make sure I am not chasing phantoms, will try to connect the Defender to a known good monitor to validate that its video signal is not the culprit. Assuming that is not the case, then maybe I start with replacing all six color related transistors (TR204-TR209) since they are cheap and the interface board is easy to remove.

I wouldn't worry about the transistor if you're getting a color signal. They'll pretty much either work, or not work IME.

Play around a little with the brightness, contrast, and color knobs. Use a mirror if you have to... just start tweaking till you get a feel for the monitor adjustments. I know it sounds like crap advise, but I went into my monitors blind and I can pretty much tune a 4900 or 4600 just buy seeing the top couple rows of pixels from the back of the cabinet.

Luckily or unluckily (depending on how you look at it) the 4600 doesn't have a brightness on the flyback, so that's one less thing to worry about... and you can pretty much ignore your XY card, so... bonus there. Have you tried turning the colours up and then adjusting the black level (sometimes on the back side of the card your video signal plugs into)? Turn it up till the colors are vibrant enough for you, even if the black on the monitor gets a little tinted (like how it's red in the bottom picture), then tune the black level till the red goes away and HOPEFULLY you're left with night bright colors.

If after you tinker with everything and you still can't get it looking like you want it... might MIGHT be time for a rejuv.
 
Play around a little with the brightness, contrast, and color knobs. Use a mirror if you have to... just start tweaking till you get a feel for the monitor adjustments. I know it sounds like crap advise, but I went into my monitors blind and I can pretty much tune a 4900 or 4600 just buy seeing the top couple rows of pixels from the back of the cabinet.
My attempts to setup a mirror didn't work well, so I did lots of back and forth trips with minor adjustments. I set R/B drive to their physical centers and cranked up Screen fairly high to get some brightness and then used the black level get some black. The result (with a lot of back and forth) was much better than anything I have previously gotten.

The one potentially relevant discovery is that the red cutoff is altering the blue/green display. With a solid red/blue/green display, the corresponding red/blue/green cutoff alters the intensity. However, when displaying either solid blue or green, the red cutoff will change the color (from blue to yellow or from green to purple). Since either a solid blue/green display should contain no red, it seems like there must be some kind of signal leakage somewhere.

At this point I believe I have the red cutoff all the way down and blue/green all the way up (or visa-versa-- but red is at the opposite extreme of blue/green cutoff to get the best display).
 
So I was finally able to test the Defender board on another monitor-- a K4900 in my Jamma test cabinet. Colors looked great so clearly the board set is not the problem. One very curious item was that the image was upside down-- something I had not expected. In any case, it indicates that the "leakage of the red into the blue/green paths is happening somewhere on the K4600. Appreciate any ideas if anybody has any.
 
Just to close this out-- chris25810 was kind enough to put my tube on his rejuv and that did the trick. The difference was amazing. Both blue/green were incredibly weak before and now they are both as strong and vibrant as red. The difference is amazing.

Only remaining issue is one random scanline at the very top edge of the monitor. Am guessing I need to adjust the vert centering to hide this, but have not played with that yet.
 
i hope you understand that you know your tube is going and will need a new one in the future.
i did the same to mine and about 5yrs (great amount of time) later it was back to the way it was.
so i just bought a new monitor and wow.
 
i hope you understand that you know your tube is going and will need a new one in the future.
i did the same to mine and about 5yrs (great amount of time) later it was back to the way it was.
so i just bought a new monitor and wow.

This has been discussed a number of times and Ken, Mod, and others who are very knowledgeable have debunked this old wives tale as far as I recall.
 
i hope you understand that you know your tube is going and will need a new one in the future.
The future is a very long time and every tube will need to be replaced at some point. But yes, I recognize this probably shortened its life.
This has been discussed a number of times and Ken, Mod, and others who are very knowledgeable have debunked this old wives tale as far as I recall.
Whether true or false, before the rejuv, my tube was borderline useless. Since Chris did this as a favor and didn't charge me for his help, its all upside to me. Just for grins, maybe I will throw an hour-meter in there. Would be interesting to get some kind of quantitative measure of how long the rejuv lasts. Given how few hours I actually play my games (though I want them to look good when I do), I am hopeful it will outlast my interest.
 
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