Weird color problem with K4600

Patrick Verner

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I found this K4600 in the basement and decided to recap it and do a tube swap. Everything seems to be going OK for the most part. It fired up and I put the TPG on it. Most of the screens look good, but the color intensity screens are not showing the third row color. Is this just the TPG on a K4600? I don't have a free game to toss tis in right now. I've never seen this happen before.

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the white looks close enough to being white and you don't have any overdrive smearing on the colors. you can try adjusting Black Level (on signal card) and balance Screen (the black pot on neckboard) to see if it changes at all
 
the white looks close enough to being white and you don't have any overdrive smearing on the colors. you can try adjusting Black Level (on signal card) and balance Screen (the black pot on neckboard) to see if it changes at all
That's was my first thought as well. I turned them up and down and tried about everything. The master brightness knob burred on the card is adjusted correct as well.
 
That's was my first thought as well. I turned them up and down and tried about everything. The master brightness knob burred on the card is adjusted correct as well.
I don't remember what the patterns look like if that was actually 2 rows or 3. lol nothing looks out of the ordinary.

what was wrong with the old tube, guns just spent?
 
I don't remember what the patterns look like if that was actually 2 rows or 3. lol nothing looks out of the ordinary.

what was wrong with the old tube, guns just spent?
It's supposed to have three rows. The tube had REALLY heavy Make Trax burn and the guns were in the bad on the B&K.
 
I have the older TPG too. The image I posted above was from Mike's Arcade website.


As I understand it (and I could very well be wrong) when looking at the pattern below:

- The band at the top should be 100% pure black
- The band in the middle should be gray. (a perfect mix of 50% black and 50% white)
- The band at the bottom should be 100% white.

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Maybe @CraftyMech can comment on my logic above. But at the very least, it sounds like you have isolated your issue to the chassis anyway and not the TPG.
 
I just noticed something else that's strange. I can't turn the guns off. This is what it looks like when only red is on:

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Red, Green, and Blue all have to be switched on to get red. On the K7000 and G07 it can display single colors.
 
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I found this K4600 in the basement and decided to recap it and do a tube swap. Everything seems to be going OK for the most part. It fired up and I put the TPG on it. Most of the screens look good, but the color intensity screens are not showing the third row color. Is this just the TPG on a K4600? I don't have a free game to toss tis in right now. I've never seen this happen before.

View attachment 833530

View attachment 833531

Try turning down the contrast/screen on the flyback. You should see 3 separate color rows, although for the grayscale on the old TPG its just black, gray, white.
 
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I have the older TPG too. The image I posted above was from Mike's Arcade website.


As I understand it (and I could very well be wrong) when looking at the pattern below:

- The band at the top should be 100% pure black
- The band in the middle should be gray. (a perfect mix of 50% black and 50% white)
- The band at the bottom should be 100% white.

View attachment 833559

Maybe @CraftyMech can comment on my logic above. But at the very least, it sounds like you have isolated your issue to the chassis anyway and not the TPG.

This is correct for the gray bars, the bars should be: 100% black, gray, 100% white.
 
I was reading that I should replace the 12KV capacitor on the neck board. Didn't help improve focus or this problem.

I had extra boards laying around, so I swapped out the interface board with one that has a lot more stuff on it and an extra pot. It shows all three lines now, but the edges are somewhat curled. It's worse with bright colors. I messed with all the related pots and it did get some better, but not perfect.

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I was reading that I should replace the 12KV capacitor on the neck board. Didn't help improve focus or this problem.

I had extra boards laying around, so I swapped out the interface board with one that has a lot more stuff on it and an extra pot. It shows all three lines now, but the edges are somewhat curled. It's worse with bright colors. I messed with all the related pots and it did get some better, but not perfect.

View attachment 833667

View attachment 833668
desolder the VR201 Black Level pot and install it on the back side of the card and you'll be able to adjust it easier then. the controls will be backwards but many of those have it installed on the back side.
 
I just found this gem of a thread:

 
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