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I'm trying to get a laptop video signal to my really old television, so that I can play movies on it.

But the TV won't accept the video signal. I found the manual online, and apparently the output has to be 480i. But I don't know how to do that -- Windows 7 will only let me set the resolution down to 800x600. Even if I get it down to 640x480- is that 480i or 480p? How do I tell the difference? How do I switch between them? How do I get the resolution down so low in the first place?

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What sort of adapter are you using for this? – music2myear Nov 22 '11 at 20:49
@music2myear VGA to component video – Carson Myers Nov 22 '11 at 20:51
VGA display has always used progressive scan. It would be quite unnatural for a computer to output interleaved signal. You'll probably need a dedicated TV converter box for that. – billc.cn Nov 22 '11 at 21:38
@billc.cn :( that is unfortunate. It appears I wasted my money. – Carson Myers Nov 23 '11 at 4:48
A lot of older laptops included a S-Video output which would be a lot easier to hookup to an older TV. They often even included an S-Video to composite adapter which would make it even easier. Check the laptop for a DIN connector that isn't for an external PS/2 keyboard or mouse. Or post the make and model of the laptop and TV for more specific help. – Brian Nov 23 '11 at 9:02
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(Note "480i" could refer to either analog or digital video.)

If your "old television" accepts what you call a "480i" signal, then that would presumably be an analog composite video signal (aka CVBS) of 525 interlaced lines. The input connector on the TV would probably be an RCA jack, color coded yellow.

The straight-forward solution (if there are no other TV inputs like component video or DVI or HDMI) is to use a VGA-to-composite video converter. Typically the converter will accept a VGA resolution of 1024x768 for a reasonable-sized Windows desktop. Video images on the TV will look good to okay, but reading menus and text will probably be difficult (or near impossible if it's a low quality TV). Do not bother trying a cheap "VGA-to-composite adapter cable"; it simply won't work if you read the fine print.

Even if you could get your laptop to output 480i (640x480 interlaced), the Windows desktop would be very small but with huge icons. Try Safe Mode at 800x600 and you'll get an idea. That's why Windows 7 does not allow low resolutions less than 800x600. BTW some video adapters can output an interlaced "VGA" (e.g. 1080i on some nVidia cards using "custom resolution").

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The TV has component input, so I bought a VGA to Component cable. Note that I'm not overly concerned about video quality since I would only use this setups to watch movies and such from my bed on the other side of the room. I already (stupidly) bought the cables and I'm hoping not to have to pay to ship them back -- It'd be awesome if I could make the VGA port output an interlaced signal, but I guess that's probably not an option. – Carson Myers Nov 24 '11 at 1:36
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A "VGA to Component cable" is not going to work. You need to use somekind of converter. A passive circuit or simple cable cannot transform a VGA (or RGBHV) video signal into YPbPr component video (nor into composite or s-video). – sawdust Nov 24 '11 at 3:23
I see, thank you. – Carson Myers Nov 25 '11 at 1:32

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