WG k7906 bottom screen curling-- but no 50/60Hz pot?!?

[angryred]

I've got a 19" WG k7906 horizontally mounted in my cab, running off an ArcadeVGA. There's always been about a 3/4" gap from the bottom of the displayed image to the bottom of the monitor screen.

If I run a game at a vertical resolution of 256 or higher, I get curling at the bottom of the screen-- that's had me running 256 vert games, like Centipede for example, at a vertical resolution of 264, which raises the image just above the curling zone. But if a game has a vert res of 288-- like Pacman-- I just have to bite the bullet and use 640x480 w/hardware stretching; 288 is apparently the highest non-interlaced resolution this monitor should be able to display (am I grasping the interlacing thing right?), so I don't have a higher resolution I can jump native 288's up to and avoid the curling zone, like I can 256's to 264.

I can get the image to reach the top of the screen, but I can't get the image down into that bottom gap.  I can adjust the vert size and position to where 288 vert res games look right, but then Windows is squooshed (in 640x480; 640x 288 is not squooshed but oddly stretched, but I figured I could play with that after I fixed the curling).

I've been using the manual here: http://www.wellsgardner.com/pdf/Service/K7000.pdf

...and I've found advice that's come close here:
http://forum.arcadecontrols.com/index.php?topic=98664.0
http://forum.arcadecontrols.com/index.php?topic=91861.0
http://forum.arcadecontrols.com/index.php?topic=96415.0

...and everything tells me I should adjust the 50/60Hz control, listed in the manual and on the board layout as VR9-- except on my monitor, it ain't there. The area where VR9 should be is slightly different than the board layout in the manual, and I can find no trace of VR9 on my board.

I called my Dad, and he got me looking closer at the schematic (page 14 in the above linked .pdf), where now I see that the 50/60Hz pot is part of a circuit labeled "alternate circuit for later production" (the board layout makes no such caveat). The alternate circuit also contains the vertical size adjustment, which is all lonely and stuff on my apparently no-so-late-production board.

So what, I ain't got no 50/60Hz pot? Am I stuck with the curling? Should I just go back to my do-fer methods of days of yore, before I read some posts on a message board that made me think, "Oh wow! I can FIX that?!?"

This was supposed to be my big victory today... 

[Ken Layton]

Some did not come with a 50/60 pot, but there was a place on the board for it. There were a couple of jumper wires bypassing the pot.

[angryred]

Some did not come with a 50/60 pot, but there was a place on the board for it. There were a couple of jumper wires bypassing the pot.

So, without that pot, do I have any options to get rid of the curling?

Thanks for the help!

(LATER...)

...After further tweaking, I managed to get the displayed image away from the curling, so now it only shows up when running games at 288 vert-- which I can't really run anyway if I want a properly sized desktop. I did manage to marry a nicely proportioned desktop with games looking good at 256, when before, the curling was affecting stuff there. So in the end it was good that I opened it up and started playing around, even if I didn't find what I went in there looking for.

Thanks again for the clarification, Ken.

[Kevin Mullins]

The Horizontal Hold and Contrast can affect the curl some as well.