Hi there!

Um, the classic way of doing it was doing it this way :
https://www.geocities.ws/podernixie/htpc/cables-en.html

These DOS utility programs re-programmed the VGA to use 15KHz instead of 31KHz, among other things.

Of course, if the graphics card has a composite or s-video output..
Then it's a lot easier. The card would take care of converting, too, likely.

Because, old classic VGA games use 200 lines, for example.
Which normally run in 70 Hz, rather than 60 Hz.
They're neither NTSC nor PAL compatible without conversion.
(-> 640x480 Standard VGA runs in 60 Hz, though) .

So it's good if the video card takes care of such things and is always outputting a TV compatible video signal.

The third method involves using an external converter box.
It converts VGA from the graphics card to Composite, S-Video, SCART RGB etc.
However, it may introduce some lag and have a lower video quality (not necessarily).

This is what you want http://mirrors.arcadecontrols.com/VGATV/pwp.n … bo.pt/pscoelho/

This TSR will set any compatible video card to output 15kHz RGBHV in DOS. You can choose between 50 and 60Hz for compatibility with PAL TVs. All you then need to do is use an external sync combiner and also attenuate the TTL level (5Vpp) sync from the video card down to a video level (300mVpp - 1Vpp)

thanks guys, that was exactly what I was looking for! ... time to heat up the soldering iron 😀

Just for fun I tried that radeon card with an s-video to scart adapter. It enables the tv-out by default when no vga or dvi connection is present so it works out of the box.
But the quality is hideous, like a cheap composite signal ... unuseable.

just finished soldering the adapter and tried vgatv. Unfortuantely it says the detected ATI card doesn't work :<
It does something however, since the vga screen turns off, saying unsupported frequency.
But the TV won't show any picture.

I then tried tv-drv, that works partly and at least confirms the adapter is fine.
As long as I stay in DOS textmode, it works. But as soon as I load a game, the TV goes black :<

Anyone know any tool that I could try?

many thanks

try vgatv with another older card

Unfortunately not possible. Its an onboard card and the case is too small for an additional one. Its a very small desktop.

You can also use an external converter box. Video quality depends on your TV and the converter and graphics card, of course.

Here are some videos I took. It has a VGA card connected to the converter. Games are DOS games in 320x200 or close.

https://www.youtube.com/@dreambyte7926/search?query=Cvbs

I had stuff off this page working back in the day...
https://www.epanorama.net/circuits/vga2tv/cindex.html

I haven't tested DOS games specifically, but my go-to VGA-to-composite and s-video converter/adapter is the EKL VGA to AV adapter.

I used this to connect an old PC running a Gameboy emulator to an old black-and-white security monitor I had. The composite and S-video from the old ATI video card I tried were garbage (as you noted) and I wanted something better, so I tried this. The difference in image quality was night-and-day, even over just composite. And with the horizontal/vertical size/position options, you can perfectly size the image to fit whatever overscan your tv has. Also has image adjustments like brightness and color saturation (the latter was helpful in my application - took it all the way to zero to clean up the composite signal since I only needed b&w anyways).

It can be had on Amazon for under $30. Also PAL compatible. And in my testing, there was no discernible lag (though now I'm curious about that, I may have to use the VGA pass-through with a side-by-side CRT monitor to see just how small the lag is). But it was low enough to play Contra and Tetris without me noticing any lag.