K7000 tweaking - finally working on this after 2 years

[dukesilverfan]

K7000 tweaking - finally working on this after 2 years

I have had this MK1 restoration project for a long time now, and I finally got it up and running last night for the first time in close to 2 years. When I first fired it up, the monitor was dark, and not adjusted properly at all. I turned the color cutoffs down all the way, and began adjusting the flyback screen, then the monitor brightness, then I brought up the color drives. I am not sure if this is the best way to do it, but you can see my colors now. I have a few questions:

1. I found this video from Buffet on adjusting the pots for a K7000. Is this probably my best resource for this:
https://youtu.be/NzJkqFJ3_vk?list=PL...b_qqIhu&t=1082

Here are my current bars, not perfected yet (the cutoffs are set all the way down)

2. See these lines on the left-side of my screen. They are not there when the monitor is off, only when it is on. It looks as if this chassis has new caps and a newer flyback, but does this still look to be a cap issue? You can see the lines in the following 3 photos:

 

[dukesilverfan]

3. My convergence is pretty good in the middle, but you can see at the bottom, and in the corners that it is off a bit. Is this normal for a k7000, or should I begin adjusting the convergence strips to try to resolve this?

 

[dukesilverfan]

It appears after doing some searching, the vertical jail bars is a fairly common problem, and unless there has been a breakthrough since Jan of 2018, there is still no fix?

https://forums.arcade-museum.com/showthread.php?t=297979&page=4

It's not horrible to play on, but you definitely notice it. And being somewhat of a perfectionist, I fear it is going to drive me nuts!

 

[ecwestjr]

Look on your neckboard and see if there is an electrolytic capacitor at C204. If so it is most likely a 4.7 mfd @160 volts. Try replacing it with either a 10 mfd @ 160 or 22 mfd@ 160 volts.

If there isn't one there then you should have a ceramic disk capacitor. If so replace it with one of the values stated above. Make sure the positive lead of the electrolytic capacitor is going to the collectors of the 3 color transistors and the negative lead is going to ground.

This has fixed this problem for me when I had those lines.

Ed

 

[mecha]

your brightness is too high. your black background should be absolute black, not have little grey pixels in it.

did you ever try adjusting the focus?

 

[dukesilverfan]

So I have the colors dialed in pretty much perfect now, per the YouTube video from Buffet, and I also got the brightness and contrast where I want it.

I will look at the neckboard cap next, and replace that, hopefully fix the lines. they don't bother me too much, but I'd like to get that.

The convergence is my biggest concern. The center is great but the corners are all off. I tried to adjust the focus, but it does not fix this, so I set it back to where it was. So now to clarify, my next steps would be the adjustment rings, or strips, right? My purity is good, and since the convergence is good in the middle, but not at the bottom and corners, that means it's likely going to need adjustment with strips, and not the ring, right? Isn't the ring kind of an adjustment globally across the whole tube, not just sections? I also looked, and there are currently 4, factory strips sticking into the neck. What should be my next step here?

 

[smalltownguy2]

Leave it alone, that's close enough.

 

[Asure]

Yup, leave alone. These are not LCD monitors with pixel perfect-ness. I learned that the hard way. And yes, the rings affect the whole screen area, not just the center. It is more than likely that this is the closest they could get this tube at the factory.

 

[smalltownguy2]

Yup, leave alone. These are not LCD monitors with pixel perfect-ness. I learned that the hard way. And yes, the rings affect the whole screen area, not just the center. It is more than likely that this is the closest they could get this tube at the factory.

+1. Really. Leave it alone.

If you REALLY want to see some convergence issues, I can show you some pics of the Wells Gardner 19K4500 I have on the bench. You'll puke.

 

[dukesilverfan]

It's just kind of hard on the eyes having the names and scores look so ghosted. There is at least 1/16" overlap in the corners since the colors do not align correctly. My old MK2 cabinet with a K7000 was spot on, so even though this tube is perfect with no burn at all, it's a little disappointing.

 

[mecha]

you know those vaunted magnetic wedges that people used to sell? that's for fixing convergence in the corners on large displays.

your tube is probably missing them. to echo what's been said 5 other times previously, leave it alone.

be thankful it works at all or that you even have it in the first place.

 

[SillyB]

Do you think this might have been a tube swap? Most of the times that I have had convergence issues at the edges but not in the middle it was on sets that had been cobbled together using mis-matched parts. My factory K7000s all have been dialed in.

It seems to me that TV tubes were less finely calibrated - anyone else think so? I've dropped in a few TV tubes that were direct swaps using factory yoke and rings and have seen convergence issues like yours. With the fact that most 25" TVs drop in to K7000s this is a very easy and common swap and there is a decent chance yours could have been swapped. You can always try your chassis with another tube if it drives you crazy.

 

[dukesilverfan]

I will trust your advices, and leave it be. I will try to replace that one cap to remove the vertical lines, and call it a day.

For my own knowledge, why does it seem that adjusting the focus also adjusts the convergence? It seems that if I tweak the focus on the flyback, the reds and blues shift slightly?

On that note, what is the best way to dial in focus? Just eyeball it with a grid pattern? It seems like brightness, colors, contrast, and hold is pretty standard, but focus is just an eyeball effort?

 

[jon713]

I have the same issue in my killer instinct 2 cab. I recently swapped out the original k7000 chassis with a newly recapped, new flyback, diodes, hot, voltage regulator chassis and both give me the same result. Double lines on the left side. Both chassis are k7000's.

Could it be the tube? It doesn't bother me and its not noticeable while playing so I think I am going to leave it as is. But its crazy that you are having the same problem.