G07 Yoke adjustment?

Zork2

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I have been working on converting an old Gorf cocktail to a Ms Pac Cocktail in the resto section.
http://forums.arcade-museum.com/showthread.php?t=175640

I've finally got the G07 chassis that came with it resurrected. But now I think the yoke needs adjusted? The maze is square at the top, but slants inward at the bottom. I put a known good chassis in and verified that it is not the chassis.

I guess my question is...
Exactly how does one go about adjusting the yoke? What am I adjusting? The entire coil with the white ring on it? I'm assuming you have to adjust it while energized?
Any pointers would be greatly appreciated....

Here is what the picture on the monitor looks like, and of course the back of the G07.....
 

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I don't think adjusting the yoke is going to help. If it would, then your entire picture would be crooked, not just the bottom.

I see this more and more with G07's. I don't know if it's the board you connect, or whether something in the pincushion circuit is starting to age badly.

You can try making both C517 and C518 a 220uf 16v cap and see if that makes it any better...
 
Thanks for the input Mod....
Well here is the issue, that chassis has been freshly recapped all the way around. Even the filter cap is new. Also this tube is doing the EXACT same this with 2 other known good chassis in it.......
 
As I said, the problem may not be your tube or yoke setup, but the board you have connected to it. If it was the yoke, then the entire picture would be crooked, not just the bottom.

And as for it being "freshly capped" - normal cap kits have C517 and C518 as a 100uf and a 220uf. I mentioned making them BOTH 220uf because that helps make the picture more square. I've seen some come in for repair that had 470uf or even 1000uf caps in there, possibly to help with geometry issues...
 
I'm trying to wrap my brain around this.... :)
So Mod,
you're saying that the "issue" lies in the interaction between the chassis and THAT specific tube? That the capacitance on those two caps is too small for that specific tube or something?

Like I said, I put TWO different G07 chassis on that tube, and I know THEY worked fine in another tube I had a while back.....yet when hooked up to the tube in question, they were identical to the pictures shown.....the bottoms were tilted in....

I'm just guessing, if I were to put the current chassis on a different tube, it would be fine?
But your saying on that tube, it requires a cap with a higher uF to get the bottom square?
Correct?
Mod if this works, I will be AMAZED! :)
I'll see if I can't scare up a couple bigger caps to drop them in there tomorrow and report back...

Thanks for your help man....
 
No, you're missing the forest for the trees. What I'm saying is that your G07 may look perfect with a Gorf board, but might be slightly curved with the Ms. Pac. This would be due to the fact that the two have different programming. You see this especially with G07's when used with some JAMMA boards like the multigame 60-in-1.

And it could be that all 3 of your G07's have a slight problem with a resistor that is slightly out of tolerance. Since they were all built at the same time, and those resistors are all the same age and most likely original, then you'd get the same result.

And then - of course - it could be that this particular tube or yoke has a weird issue with it. Moving the same chassis and game board to a different tube and getting a different result would prove this....
 
AHHH I see Mod.....
Ok well since I don't have another tube to try right now I did this.....

First I replaced C517 with a 220uF 25v cap.....minimal change
Then I replaced C518 with a 470uF 25v cap....maybe a bit of change
Then I replaced C517 with a 470uF 25v cap, again maybe a slight improvement?
So I said to hell with it and dropped in 1000uF 25v caps in both C517 &518...
Not perfect, but a definite improvement.....
So just for Sh!ts and giggles, I dropped the original caps back in just for a comparison....
WOW....since I replaced those little by little, I didn't realize just how much of an improvement the 1000uF caps had given me!
The right side looks about even, however now the left side has a slight droop to it?
Mod, is there a cap that is associated with the left side that can be replaced that will bring UP that side?
From the looks of the Mr Do burn on the tube, this Gorf cocktail has been like this for a LOOOONG time as the burn is even at a slant!!
I will take a pic this evening once the light in my shop is better and post it......

MOD your knowledge always AMAZES me!
A million thanks for your help on this issue!
 
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Here is a pic of the after.....
Way better, but not perfect. This was the best I could do dialing in the pots and H-coil...
 

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Looks pretty good. I'd turn your red down slightly (is that red tint in the "black" background?), shift your image slightly down, and probably live with that if it were me...
 
Na, the red is fine, just a crappy picture. My camera doesn't like to take pics of stuff on monitors!
I was thinking the same thing, I can live with it.
It is a HUGE improvement! A "non-klover", may not even notice? :)
I was tempted to go even bigger on the caps, say 2200uF? I wonder if that would have done anything more?
Oh and thanks again Mod for your help......
 
:) TRUE!!
Just as a FYI, as I went higher and higher on those caps, each time I had to turn down the brightness on the flyback. Not sure exactly what that is a result of electrically speaking, just noted it. But I suppose there could be a limit to the size of the cap because the result would be a super bright screen and the fly would be down all the way???
 
Maybe. I know there is a resistor in that area that can cause colors to disappear if it goes up in value, so it wouldn't surprise me that changing cap values changes brightness...
 
AHHH I see Mod.....
Ok well since I don't have another tube to try right now I did this.....

First I replaced C517 with a 220uF 25v cap.....minimal change
Then I replaced C518 with a 470uF 25v cap....maybe a bit of change
Then I replaced C517 with a 470uF 25v cap, again maybe a slight improvement?
So I said to hell with it and dropped in 1000uF 25v caps in both C517 &518...
Not perfect, but a definite improvement.....
So just for Sh!ts and giggles, I dropped the original caps back in just for a comparison....
WOW....since I replaced those little by little, I didn't realize just how much of an improvement the 1000uF caps had given me!
The right side looks about even, however now the left side has a slight droop to it?
Mod, is there a cap that is associated with the left side that can be replaced that will bring UP that side?
From the looks of the Mr Do burn on the tube, this Gorf cocktail has been like this for a LOOOONG time as the burn is even at a slant!!
I will take a pic this evening once the light in my shop is better and post it......

MOD your knowledge always AMAZES me!
A million thanks for your help on this issue!

Old thread bump!

But this solved a problem with my G07/Centipede with the drooping / sagging on the left side of the screen.
 
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