8400GS and possibly 8xxxx TV-Out FIX Hardware fix to enable use of S-video to Composite adaptors
For a hardware fix to the problem of 8400Gs and possibly 8XXX series cards not detecting S-video to composite adaptors go to the following site.

[url="http://www.epanorama.net/circuits/svideo2cvideo.html"]http://www.epanorama.net/circuits/svideo2cvideo.html[/url]

Build the adaptor but add a 180 Ohm resistor between the crominance output C (Pin 4) and ground. It's very simple - just one capacitor to which a resistor is added.

Everything will then work normally and the driver will show that S-video has been detected and the the window for selecting video standards will be displayed.

BACKGROUND
I bought a Galaxy 512MB 8400GS and ran into the problem of the S-video to composite adaptor not being detected. As others have suggested in this forum the problem seemed to be caused by the hardware, firmware or driver, looking for some kind of load on the output of the video card but not finding it.

As Tomi's circuit shows, the card will see a load on the luminance line Y, (Pin 3), because there is a circuit through the TV set and back through the Ground to the card. However, there is only a capacitor connecting the crominance line to the luminance line. Capacitors pass AC signals which allows the colour information (crominance) to pass through the capacitor and be added to the black and white information on the luminance output.

However, capacitors block DC voltages and if the card is looking for a DC voltage on the crominance pin it won't find it and TV detection will fail. The solution therefore is to supply a DC path via a resistor. Hence the addition of the 180 Ohm resitor to Tomi's circuit.

Because of concern at introducing a current drain on the video card's chip set, several values of resistors were tried. At 1K (1000 Ohms), nothing worked. At 560 Ohms it would work but only if the driver had already been set up using a lower value. At 270 Ohms it would work including new installations but the the driver still displayed "Auto Select." At 180 Ohms it all works normally including a new clean installation of XP Pro and 185.85 drivers that came with card.


If anyone really want's to get into it, this link suggests that the 8400GS (and in my opinion possibly the 8xxxx series) has inbuilt outputs for Composite on it's own.

[url="http://en.wikipedia.org/wiki/S-Video"]http://en.wikipedia.org/wiki/S-Video[/url]

Certainly my own card has the non standard 7 pin S-video socket they describe.

DISCLAIMER- I'm NO EXPERT so please only try this at your own risk. It worked for me but that's no indication it will work for everyone or not do any damage.
For a hardware fix to the problem of 8400Gs and possibly 8XXX series cards not detecting S-video to composite adaptors go to the following site.



http://www.epanorama.net/circuits/svideo2cvideo.html



Build the adaptor but add a 180 Ohm resistor between the crominance output C (Pin 4) and ground. It's very simple - just one capacitor to which a resistor is added.



Everything will then work normally and the driver will show that S-video has been detected and the the window for selecting video standards will be displayed.



BACKGROUND

I bought a Galaxy 512MB 8400GS and ran into the problem of the S-video to composite adaptor not being detected. As others have suggested in this forum the problem seemed to be caused by the hardware, firmware or driver, looking for some kind of load on the output of the video card but not finding it.



As Tomi's circuit shows, the card will see a load on the luminance line Y, (Pin 3), because there is a circuit through the TV set and back through the Ground to the card. However, there is only a capacitor connecting the crominance line to the luminance line. Capacitors pass AC signals which allows the colour information (crominance) to pass through the capacitor and be added to the black and white information on the luminance output.



However, capacitors block DC voltages and if the card is looking for a DC voltage on the crominance pin it won't find it and TV detection will fail. The solution therefore is to supply a DC path via a resistor. Hence the addition of the 180 Ohm resitor to Tomi's circuit.



Because of concern at introducing a current drain on the video card's chip set, several values of resistors were tried. At 1K (1000 Ohms), nothing worked. At 560 Ohms it would work but only if the driver had already been set up using a lower value. At 270 Ohms it would work including new installations but the the driver still displayed "Auto Select." At 180 Ohms it all works normally including a new clean installation of XP Pro and 185.85 drivers that came with card.





If anyone really want's to get into it, this link suggests that the 8400GS (and in my opinion possibly the 8xxxx series) has inbuilt outputs for Composite on it's own.



http://en.wikipedia.org/wiki/S-Video



Certainly my own card has the non standard 7 pin S-video socket they describe.



DISCLAIMER- I'm NO EXPERT so please only try this at your own risk. It worked for me but that's no indication it will work for everyone or not do any damage.

#1
Posted 08/07/2009 01:11 PM   
Scroll To Top