WG19K4675 Vertical Raster Not Centered

[smartbomb2084]

Hello all,  I have a WG19k4675 from a ZAXXON cabinet and I am unable to get the pictutre centered vertically. The picture is shifted at least one inch to the left regardless of what game signal is being fed to it.  I tried several.   The yellow jumper wire centering system has no effect no matter what position it is in.  I have swapped VERT/HOR and INTERFACE boards with ones from an earlier K4600 version and the problem persists.  I have replaced all the electrolytics including C633 (bi-polar).  I am running out of ideas, can anyone help?

THANKS

[Rickn]

So then slighly confused, I do not know the cabinet- is the monitor mounted vertically or horizontally>
The reason I say that and I am confused is that you start off saying vertical centering and then say Left to Right.

[Kevin Mullins]

Zaxxon...vertically mounted.... so left and right would actually be up and down.

[smartbomb2084]

Yes, that is correct.  We all know that in monitor speak horizontal is always the long dimension of the tube and vertical the short dimension.  In a game with a vertically oriented monitor, the player will see these as reversed but the circuitry doesn't care that the tube is turned 90 degrees. 

[Ken Layton]

In an old back issue of Star Tech Journal there was an article detailing a simple mod to the 4600 series monitors to give the centering adjustments more range.

[SirPeale]

In an old back issue of Star Tech Journal there was an article detailing a simple mod to the 4600 series monitors to give the centering adjustments more range.

That sounds neat; can you get any more details about this?

[smartbomb2084]

Well,  yesterday morning after switching around yoke wires and trying another yoke with no change, I decided to put a 1K resistor in paralell with R649.  Change the resistance, change the screen size just as if a pot was attached to it.  Looking through old notes yesterday,  I found the exact STJ article Ken Layton mentioned.  It says to use a 680ohm resistor.  I tried it and the 1K gave a more centered picture. The STJ article also says to put a 500 ohm resistor in series with a 500 ohm pot connected in paralell with R649 to give a fine tuning feature.  I am a bit confused on this because pots have three connections and R649 has only two ends and I would think that the wiper connection must go on one end of R649 and one end of the resistor in the pot on the other but where does the third leg go?  Actually, it seems to work with the third leg of the pot UNCONNECTED. Can this be right?  I have the diagram from the article but I don't know how to post it. When I click the 'insert image' icon on the reply page it just puts up [img].

[Kevin Mullins]

I have the diagram from the article but I don't know how to post it. When I click the 'insert image' icon on the reply page it just puts up [img].

That's for if you have a web link to the image.

Use the Additional Options below the message box when you reply to "attach" an image if it's an image you have on your computer.

[smartbomb2084]

Here it is..... I hope

[Rickn]

Sook if the mod does not fix the problem, here is another option- it is very simple, but we do it a few hundred times a day.

Because the monitor is now rotated 90 degrees, suddenly the earths magnetic fiels affect it differently.

The earth has 2 magnetic fields that affect the way the tube works.

One is horizontal magnetic field, for example if you take a monitor in it's normal orientation and rotate it from North to south directions you will notice the picture will rotate - it does a lot more, but won't bother you with details.

The other is vertical magnetic field, this has a left to right affect onthe tube.

All said now that you have turned the tube vertically it sees a different magnetic field so the picture will shift left to right.

Before you try anything else I would have suggested, turn the monitor 180 degrees, you will see a left to right or as the monitor is vertical mount, a so called vertial shift.

If this is enough to fix your problem, I can tell you how to mount it according to the cabinet and adjust the purity rings as needed.

Probably a whole lot more than you wanted to hear...


Rick Nieman
Rick@niemandisplays.com