K4600 horizontal shift mod?

modessitt

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I seem to recall a while back someone posting something about changing a cap or resistor value to shift the horizontal center one way or the other. Perhaps it was a different model?

I put a P317 on this, but the chassis is too old for the horizontal-centering to work.

Does the interface board control the center (which would explain the P317 having the adjustment)? If I traded out to a different interface card, would it have any effect on the center?

My picture is about 2" to the right. I have the jumpers to move it right, but it won't move left to where I need it to be. I've adjusted L351 to the furthest point it can go and still boot up synced...
 
think bob roberts had a paragraph about it but i cant look right now

this isnt what i was thinking of. still looking


While you are here, you may as well know about a couple other quirks of the K4600. If you are still experiencing horizontal difficulties, or vertical for that matter, these 2 plug in cards....actually 3 as the regulator card to the far left, also plugs into the main....often have cold solder joints on both the header pins on the main board & the card connectors. To remedy this you need to flow a bit of new solder into the old to soften it for removal. The little $5 solder sucker is the quickest way to clean this old solder out. After you have a few pins cleaned, you can flow some new solder onto them before proceeding, to maintain stability to the end. Another quirk that is often overlooked is the cap at position C614 on the main board.
keystone.jpg
This cap bridges the pincusion xformer and when it grows weak it causes the picture to appear trapezoidal, or what techs call "hourglass" or "keystone". The center of the pic can bow inward )( or outward ( ), hence the 2 terms. The reason it is overlooked so much, is that in their infinite wisdom of design, they chose to mount this under the V/H card between the 2 connectors, forcing the radial cap to be mounted with extra long leads & then bent to a laying out-of-the-way position on the main board to allow the V/H card to plug in.
 
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i gotta figure out how to rigup the vertical shift on my 4600.. i have one with no jumpers and the stupid image is about 1/2" too low.

i have a 4900 i could use but the neckboard is literally missing a piece so i dont know how to stick it all back togther.
 
While you figure that out I figure I'll move this to the monitor section.
 
think bob roberts had a paragraph about it but i cant look right now

this isnt what i was thinking of. still looking


While you are here, you may as well know about a couple other quirks of the K4600. If you are still experiencing horizontal difficulties, or vertical for that matter, these 2 plug in cards....actually 3 as the regulator card to the far left, also plugs into the main....often have cold solder joints on both the header pins on the main board & the card connectors. To remedy this you need to flow a bit of new solder into the old to soften it for removal. The little $5 solder sucker is the quickest way to clean this old solder out. After you have a few pins cleaned, you can flow some new solder onto them before proceeding, to maintain stability to the end. Another quirk that is often overlooked is the cap at position C614 on the main board.
keystone.jpg
This cap bridges the pincusion xformer and when it grows weak it causes the picture to appear trapezoidal, or what techs call "hourglass" or "keystone". The center of the pic can bow inward )( or outward ( ), hence the 2 terms. The reason it is overlooked so much, is that in their infinite wisdom of design, they chose to mount this under the V/H card between the 2 connectors, forcing the radial cap to be mounted with extra long leads & then bent to a laying out-of-the-way position on the main board to allow the V/H card to plug in.

I can't believe someone is quoting BobRob monitor stuff to me.

channelmanic said:
While you figure that out I figure I'll move this to the monitor section.

Where the hell did I post it? Stupid work computer.

KenLayton said:
Perhaps this is the thread you were thinking of:

http://forums.arcade-museum.com/show...ntal+centering

Ah, there it is! Thanks Ken (and Darren)...
 
Glad it proved useful. Hoping you sucessfully got your main board modded to support the horiz centering pot.
 
Glad it proved useful. Hoping you sucessfully got your main board modded to support the horiz centering pot.

Worked like a charm! Had to scrounge to find two 6.8k-ohm resistors, and then had to dig through the schematic to figure out which connector was which since they're not labeled on the board (perhaps edit your instructions with "interface card" and "X/Y card" in parentheses after each connector location?). Glad you still had the pics online.

Swapped out the width cap for one slightly smaller in value (from 394 to 224) to get better width, and I was able to adjust it to full and centered picture!

Thanks...
 
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