Wells Gardner 4901 Curling Issue

Antifrodis

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I recently re-capped a WG 4901 chassis and replaced the flyback with a new one. This is the early 3 pot version of the chassis. I still have an issue where there are horizontal lines at the very top of the screen, and it is a bit squished and cut off at the top as well. I tried moving the vertical position jumper to all 3 positions, as well as slightly adjusting the vertical hold. No improvement.

I found an old thread where people say that the issue would be a mismatched yoke/chassis.

https://forums.arcade-museum.com/showthread.php?t=83994

Well, according to the information given in that thread, I appear to have the correct yoke for my chassis. The sticker on my yoke is marked 2021111194.

When I was installing the cap kit, I found two variances in caps. For C308, my chassis had a 3.3uf 50V and I replaced it with the 2.2uf provided in the kit. Also, for C313, my chassis originally had a 47uf 160v and I replaced it with a 100uf 160v, also provided with the kit. From everything I've read, the caps included with the kit are the correct ones. Would this be causing an issue? These two capacitor variances are noted in this old thread.

https://forums.arcade-museum.com/showthread.php?t=111159

Does anyone have a suggestion as to how to fix this problem? Thanks for any help.
 

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I capped a 4900 in a Tapper earlier this year that was fine (but had bad caps) and after the cap job it had that curl.

Now I just have to remember what cap it was that was wrong. I think it was a 10mf cap that was a 33 or something from factory.

Let me see if I can figure it out...
 
OK, try this.

I think it was C313. Original cap was 47mf and the kit came with a 100mf cap. I think the 100mf cap on a board that requires a 47mf cap causes that fold over.
 
maybe this is part of the yoke/chassis mismatch. Would be nice to have a solution since I've run across this more than one time myself.
 
Try a different video signal source to see if the foldover is still there. I understand some of the 60 in 1 boards exhibit a foldover problem on G07, K4900, and K7000 monitors.
 
Try a different video signal source to see if the foldover is still there. I understand some of the 60 in 1 boards exhibit a foldover problem on G07, K4900, and K7000 monitors.

Here's an original Konami pcb. Same issue unfortunately. I had to adjust the screen pot on the flyback to see the horizontal lines, but the score is still squished a bit.
 

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try changing that cap I mentioned. If not to see if it will work but to fix your problem.
 
try changing that cap I mentioned. If not to see if it will work but to fix your problem.

Will do. I'll see if I have one laying around. Otherwise, I could put the original cap back in for testing purposes, until I can order one. I will report back.
 
Will do. I'll see if I have one laying around. Otherwise, I could put the original cap back in for testing purposes, until I can order one. I will report back.

Do you know if the original cap was 47 or 100?

If it was 47 it would be 47mf @ 160VDC or better.
 
I replaced the 100uf 160v cap with a brand new 47uf 160v cap, which has the same rating as what I originally found on this chassis. No difference. I'm at a loss at this point. Any other suggestions?
 
I replaced the 100uf 160v cap with a brand new 47uf 160v cap, which has the same rating as what I originally found on this chassis. No difference. I'm at a loss at this point. Any other suggestions?

well crap, I was really hoping that we were onto something.

It didnt do this before the cap kit right? I'd go back over the kit to see if there were other cap values that were different from what was on the board and whats in the kit.
 
I know for sure there was a cap that caused this fold over, or whatever you want to call it, in that Tapper I capped earlier this year.

Try this one....

"C311 in my cap kit calls for a 4.7uF 160v cap. I just pulled a 10uF 160v cap from the board"
 
well crap, I was really hoping that we were onto something.

It didnt do this before the cap kit right? I'd go back over the kit to see if there were other cap values that were different from what was on the board and whats in the kit.

It may have had this issue before I worked on it. It was putting out such a poor image when I got it that I might not have even noticed if it was a problem at that point. I rejuv'ed the tube, so it looks great now on that end. It's still the chassis that's giving me issues. I could try and replace that 2.2uf cap with the 3.3uf that was originally in it, but I can't see how that would make a difference. I guess I won't know until I try.

In the meantime, I'm open to any other suggestions.
 
It may have had this issue before I worked on it. It was putting out such a poor image when I got it that I might not have even noticed if it was a problem at that point. I rejuv'ed the tube, so it looks great now on that end. It's still the chassis that's giving me issues. I could try and replace that 2.2uf cap with the 3.3uf that was originally in it, but I can't see how that would make a difference. I guess I won't know until I try.

In the meantime, I'm open to any other suggestions.

I dont think its either of the 2.2mf caps. 10mf seems very familiar to me.

Try that other suggestion I had.
 
I dont think its either of the 2.2mf caps. 10mf seems very familiar to me.

Try that other suggestion I had.

I found the thread that mentioned doing what you said. It looks like it was in reference to a 25" chassis.

In the meantime, I went ahead and got the JROK Multi-Williams PCB. It displays perfectly on this monitor. I can't see those odd lines at the top of the screen unless I turn up the "screen" pot on the flyback. Problem solved. So the moral of the story is not to use a 19 in 1 with an early K4900 chassis. There's no way to adjust out that curl that I could find.
 
I found the thread that mentioned doing what you said. It looks like it was in reference to a 25" chassis.

In the meantime, I went ahead and got the JROK Multi-Williams PCB. It displays perfectly on this monitor. I can't see those odd lines at the top of the screen unless I turn up the "screen" pot on the flyback. Problem solved. So the moral of the story is not to use a 19 in 1 with an early K4900 chassis. There's no way to adjust out that curl that I could find.

it was a 19" in a tapper. Maybe thats a different thread?

Anyway, I'm going to experiment next time I get a 4900 on my bench. I'd really like to have a definitive answer.
 
it was a 19" in a tapper. Maybe thats a different thread?

Anyway, I'm going to experiment next time I get a 4900 on my bench. I'd really like to have a definitive answer.

matt i have hundreds of chassis you can experiment on....;) when should i have your plane ticket ready.:rolleyes::eek:
 
matt i have hundreds of chassis you can experiment on....;) when should i have your plane ticket ready.:rolleyes::eek:

Damn dude, I'd love to come up there!

No need though. I'm sure I'll have a k4900 run across my bench soon.

Hell, I'll be back at the place with the Tapper towards the end of this month. I just need to remember to pull the chassis and look for the cap thats different to figure this out.
 
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