Strange 'cut-off' across top of screen.

[ckong]

OK, I'm running Groovymame with an Ati radeon 4550 HD card and CRT Emudrivers on a Windows XP PC, spitting out 15 Khz through a homemade VGA > RGB Scart cable (including 5V + 100 Ohm resistor and 12V from the PC power supply).

I'm testing this setup with 3 European 21" RGB Scart TV's (2x Philips and 1x Sony) and 1 true 15K 27" Barco DCD2740 monitor, and I'm having a particular issue with the Sony TV and the Barco monitor. Where the 2 Philips TV's present a good overall picture and geometry, the Sony TV and the Barco monitor show a 'cut-off' section across the top of the screen, see attached picture on the Barco displaying a test screen in 640x480 resolution.

What causes this and how can I solve it?

[lilshawn]

it's just a little overscan... dial down the vertical size a tad and call it good.

[Paradroid]

What causes this and how can I solve it?

Open up Arcade OSD and fiddle with your vertical porches. Looks like your monitor is cropping a line or two. You should be able to shift the image down using Arcade OSD and then update your GroovyMAME monitor specs accordingly.

[ckong]

Both thx for your replies.  I never did mess a lot in ArcadeOS, but I will try to do that. 

[haynor666]

Typical for Sony tronitrons, all Sony TVs that I had/have have the same problem. Instead of creating modelines use alternative custom range instead of arcade_15.

Look here http://forum.arcadecontrols.com/index.php/topic,148828.msg1638016.html#msg1638016