bad image on crt-tv via vga-output

porferlam · 10-21-2006, 07:11 AM

hello, i'm sorry for my english.

i have a labtop with the next specifactions:

acer 9411AWSMi
1,6 Ghz dual core
1 Gb Ram
Geforce 7300 => no tv-out(s-video)
=> vga-output

I have tried to connect my labtop via a vga to s-videocable in combination with the program "powerstrip 3.7." I used the settings 768x576 but the screen(tv) flikkers through.

can i display the image from my pc to the screen(tv) with changing anything on the proportions of my display or is there another solutions to solve this.

any help is welcome.

ChristopherDAC · 10-21-2006, 03:23 PM

I don't quite understand your problem. You say the screen flickers? If you are using 768×576 resolution, I guess you are in a PAL or SECAM country, and are running a 50 Hz refresh rate. The signal on the S-Video cable will be 625 lines, 25 frames per second (interlaced 2:1), 4.43 MHz chroma carrier, if I do not misunderstand you.
In this case, the screen will always flicker, because the of the low refresh rate. This is normal for PAL and SECAM televisions. You can alleviate the effect by turning down your screen brightness and darkening the room, or by drinking beer (which lowers the critical fusion frequency of the eye).

Or is this something you don't see with ordinary TV broadcasts? Do you perhaps mean that the picture jumps up and down (jitter), or rolls vertically, or tears horizontally?

Tekara · 10-21-2006, 10:18 PM

I have never seen a vga to s-video cable before; you usually need a scan converter box due to the differences in how the signals are interpreted.

ChristopherDAC · 10-22-2006, 01:32 AM

I think what he actually has is a breakout cable. I have one, on an All-In-Wonder card, which has a single output connector for two VGA monitors, S-Video, and composite, and uses a breakout cable rather resembling a squid.

porferlam · 10-22-2006, 03:45 AM

i'm living in belgium where we have PAL/SECAM. How many lines,frames are there per second and must i used interlaced?

About the vga-to-s-cable is the same as below.

vgaconnector(man)___________s-video-connector
\__________composiet

i have searched further and i found next schema on the link below.
http://www.nexusuk.org/projects/vga2scart/

i made this convertor but the image on the tv is now a fine line who rolls vertically.
Changing the vertical and horizontal settings in powerstrips 3.7 doesn't change anything.
i don't know anything about the settings.

Is this convertor a good one?
in the link, they say to use the Modeline "768x576pali" 14.76 768 789 858 944 576 580 583 625 -hsync -vsync interlace. How must i do that in Powerstrip?

Christophe DAC thx anyway for the response, i need the help.

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porferlam · 10-22-2006, 03:49 AM

here is the link where you can see the vga-to-s-videocable.

http://videoclub.tiscali.nl/info/100a9befca5.html

ChristopherDAC · 10-22-2006, 03:46 PM

Yes, that's a breakout cable. The video card presumably sticks the composite and S-Video on some of the unused pins of the VGA connector.

The PAL and SECAM broadcast systems of Europe both use the CCIR television standard, the difference being only in color transmission. The standard is :
Lines per frame 625
Visible lines per frame 576
Interlace 2:1
Frame Rate 25 Hz
Vertical Synchronizing Frequency 50 Hz
Horizontal Synchronizing Frequency 15 625 Hz

I was not able to access the page you linked, but I would say, for the moment, stick with the S-Video connector from your video card. I suspect that the "GeForce 7300" has a function which will create a video signal of the CCIR-PAL standard from your settings, by downconverting the signal which is output to the PC monitor when using the standard connector.
Probably you need to adjust, ot your desktop using PowerStrip, but something in the graphics card driver settings. My ATi card has a very complex user interface, which resides in the System Tray as an icon. There are at least four models of the 7300 : which one do you have?

porferlam · 10-22-2006, 04:31 PM

the link that doesn't work, works normaly. maybe try it another time.

in the displayproportions i found just "GeForce Go 7300".
is that enough or must i search anywhere else?

thx.

ChristopherDAC · 10-25-2006, 11:18 AM

Can you please describe the problem you are having with the S-Video connexion? If you do not, we can't tell what's going on. Does the image become alternately bright and dark? Does it jump or roll up or down? What is bothering you?

I think you have gotten off to a wrong start with PowerStrip. Your NVidia drivers should have some kind of Control Panel utility, in which you can set up "dual monitor support" or "TV Output" or something of this kind. And when you say "display proportions", do you mean "display properties"? Is this the Windows interface for the Desktop? If so, you probably need to find the NVidia utility, as I said.

porferlam · 10-26-2006, 05:29 AM

the image on the tvscreen rolls down and is grey(=black and white).

in the "display properties"(from the geforce Go 7300) i use the "dual monitor support".

Do you need anything else?
What must i do now.

ChristopherDAC · 10-26-2006, 10:51 AM

Try simply setting your refresh rate at 50 Hz and see what happens. It is possible that your video card is either dual-format, or an NTSC output model, in which case the fact that it is grey-scale only and rolling could be the result of wrong vertical (60 rather than 50) and subcarrier (3.58 rather than 4.43) frequencies. The small difference in the horizontal frequency would be well within the range of the TV's internal adjustment. Setting the refresh rate to 50 Hz might kick it into PAL mode, or you might need to activate some option for that.

porferlam · 10-26-2006, 04:34 PM

first and for all, i forgot to said that i have a crt-tv(100Hz).

i was able to set the refresh rate at 50 hz(576x625), but the screen still scrolls down.
then i tried the resoltion 800x600 with a refresh rate at 100Hz. Here the image on the screen is more stable(but not enough)and i see it 6 times, wich scrolls slowy down, from the left to the right.

i was also able to set the output for the tvscreen to PAL-mode.

maybe something that can help: in the "display properties" i had enabled the "dual view". the image on my labtop looks normal, but when i push the button "print screen" and copy this in paint, then i see the screen from my labtop + the image shown on the tvscreen.
the image shown next to the image from my labtop, is just a part(1/3) of the full screen.

what do you mean by the "subcarrier frequencies)?

Thx again.