[mythtv-users] Troubleshooting a VGA-SCART converter

Alex Butcher mythlist at assursys.co.uk
Mon Oct 3 15:59:34 UTC 2011

On Mon, 3 Oct 2011, Petteri wrote:

> 02.10.2011 21:55, Alex Butcher kirjoitti:
>> On Mon, 3 Oct 2011, Andrew Cranwell wrote:
>> ...however, when I bought a new GT240, I found that X would accept the
>> modelines, but the card wouldn't output a signal that my TV would
>> display. My (relatively untested) theory is that any card with an analogue
>> composite/S-Video output can output modelines with <15MHz dot clocks, but
>> that cards with only HDMI TV outputs can't. I suspect you're out of luck
>> with your GT520.
> I'm using nexusuk adapters with GT210 and GT220 and neither have
> analogue tv-out.

Interesting, thanks for the data points. I wonder if it's something specific
to my Asus ENGT240 SILENT/DI/1GD3, or if not, the GT240...

>>> I suspect the first problem is that the scan frequencies are simply too
>>> high - X doesn't seem to accept the 15.6kHz modelines (from
>>> http://www.mythtv.org/wiki/Modeline_Database) but will use the 31kHz
>>> non-interlaced modes - hopefully this will actually work as the TV can
>>> supposedly take 100Hz progressive input.
> If X isn't accepting modelines you should add ModeValidation and UseEDID
> config lines to xorg.conf and disable (all) validation checks (they are
> useless anyway with the adapter).
> I'm using nexusuk adapters with two 36" CRTs @1024x576/25i and picture
> quality is excellent so it is worth the hassle IMO.

Agreed. :-)

> For fine-tuning modelines I used glxgears with vsync to adjust output to
> exactly 50.000 hz.

The xorg.conf I linked to in my original message should work

Best Regards,

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