VGA-RCA

[watermelon]

i want to use my pc on my tv without having to use a video card. is it possible to convert vga directly to phono rca?

if so, does anyone have the pinouts?

im guessing its not a simple as this and requires some extra tomfoolery.

[kendrick]

Briefly, you need a special video card or a separately-powered convertor to do what you want. VGA output is essentially analog RGB at 15 kHz. Composite video combines color, brightness and sync information on one wire. There is no composite output on a normal VGA port.

-KKC, who can't find a copy of Ico to save his life.

[phreak97]

vga is 32kHz, not 15kHz. if it were 15kHz, thisngs would be a crapload easyer.

[viletim!]

VGA can be whatever frequency you like, esp. true for newer VGA cards. Though coaxing it into a h. freq. as low as 15khz is a lot trickier than, say, changing the resolution in windows.

to the OP, what are you really trying to do?

[watermelon]

take i take vga into uk scart without lots of messing about?

[phreak97]

probably not..

[Yod@]

take i take vga into uk scart without lots of messing about?

Depends what you're trying to do.
You could make up a VGA-SCART lead and use PowerStrip to force your GFX card to output @ 15KHz.

[watermelon]

so can i wire a vga connector to a scart like this:



then install the PowerStrip and it will work?

[atom]

Assuming powerstrip works with your onboard video, then yes, it should. Power strip could have bad effects on your video card however, and seeing as its onboard, yeah. Cheap video cards have s-video out, but go ahead give it a shot. What do you have, intel extreme?

[Yod@]

Bear in mind that you'll also probably have to supply a voltage to SCART pins 8 and 16 in order to switch the TV into RGB mode.
One of my friends doesn't even use a PC monitor at all, he just has his PC permanently connected to the TV using one of these VGA-SCART leads and PowerStrip.

Also note that PowerStrip can be a real pain in the ass to set up - it's not *too* hard to get Windows to ouput at 15KHz, but you may have to set up a whole bunch of custom resolutions etc in order to get it working properly with PC games.
I strongly recommend that when configuring PowerStrip you control the PC via another machine networked to it - use a program like VNC.
It means that you can use the networked machine to tweak the output settings even if you don't have a stable/legible image displayed on the TV.

You still haven't told us what you're planning to do - run Windows? PC games? Emulators?

[Guest]

i basically want a second computer to use msn, opera and winamp with when im playing games. it would be nice to be able to play roms/movies on it occasionally. its pointless, but it will be useful

i dont have a second moniter, and theres a 32" tv right next to me i can use instead.

i made small case for the system with just the mobo, a hard drive and network card. it has a custom power supply, which is really small and is external from the case. the whole case is 26cm by 21cm, it looks really sweet.
i dont have room for a video card, and if i can help it id rather avoid spending money if i can suffcently hack it.

[atom]

Yeah, I see why you want to avoid a video card in that case (no pun intended). Go ahead and try the mod I see youve already googled for.  

[viletim!]

watermelon,
Connecting the two sync signals together is bad for the video card. Do the job properly, see http://members.optusnet.com.au/eviltim/scart.htm

Though I don't think you'll be happy with the end resault to be honest. You can't get any more than 400 lines (you can get 800 lines with interlacing but the 25hz flicker will drive you mad) which is too low to be practical for anything but games.

[vileitm!]

I misread that diagram, I see just uses the vertical sync signal. It still won't work with a standard video card.

[Yod@]

You misread the diagram again, it uses composite sync.
And why won't it work on a standard card? I've used it on quite a few.

[viletim!]

You misread the diagram again, it uses composite sync.

The diagram makes no mention of that.

And why won't it work on a standard card?

Because a standard card will output horizontal (not vertical as previously stated, I just looked it up) sync on pin 13. Furthermore, a standard (typical) VGA monitor isn't guaranteed to work properly if fed a composite sync signal.

I've used it on quite a few.

Quite a few non-standard video cards perhaps?

[Yod@]

You misread the diagram again, it uses composite sync.

The diagram makes no mention of that.

My mistake, I skim-read your reply and thought you were talking about the original diagram posted.

Because a standard card will output horizontal (not vertical as previously stated, I just looked it up) sync on pin 13. Furthermore, a standard (typical) VGA monitor isn't guaranteed to work properly if fed a composite sync signal.

I can't say I noticed any problems when using pin 13 as a composite sync source, but I normally tie the horizontal and vertical syncs together to be on the safe side - no circuit, just join the wires together. Works for me, see below.

I've used it on quite a few.

Quite a few non-standard video cards perhaps?

Not at all. GeForce 2 GTS, GF4 ti4400, Voodoo 3, TNT2 cards, older cards such as Trident/S3/ATI Rage cards, and a couple of laptops (sorry, can't remember what chipsets they had).
You'll find that a lot of other AdvanceMAMErs use these leads to output 15KHz RGB signals natively. Have a look on the AdvanceMAME site if you're interested in looking at the list of compatible cards, it's fairly substantial.
I've used all of these cards in my arcade cabinet over a substantial period of time, with no ill-effects.
As I mentioned, one of my friends uses one of these leads to connect his PC to his TV, and his machine runs 24/7. He recently upgraded to a 6600GT card, and has had no trouble with that either.

EDIT: Wait, are you still talking about the circuit you've linked to when you say it won't work on a standard card? IDGI. Why link to it then?
The first diagram posted in this thread works fine for me with the horizontal/vertical syncs directly connected.

[viletim!]

My mistake, I skim-read your reply and thought you were talking about the original diagram posted.

I was. This is getting a bit confusing so i'll clarify.
I'm not saying that video card timings, etc can't be fiddled with to work with TVs. I've (ab)used all sorts of VGA (from an 8 bit ISA card to a new geforce thing) cards for this purpose and can say that most of the time it works pretty well.

As far as sync goes...
The first picture, posted by watermelon, with the wavy lines, is only applicable to a select few video cards - mfg'd by ATI and can output comp sync. If this was to be connected to a standard card the picture will roll verticaly (at best).

The link I posted (my page) contains info that should be applicable for all VGA cards (the exception being the Ultra Simple... circuit which doesn't work on most older (pre-agp) cards).

Connecting horizontal and vertical sync signals directly together doesn't make composite sync. It makes an deformed waveform bearing only slight resemblance to it. Every time the signals differ from each other they short each other out - it can't be good for the video card. The only reason it works at all is that a standard TV is excelent a dealing with really shitty sync signals (eg. sync from a weak TV station's signal).

And that's also neglecting the fact that the logic signal from a video card is 5 times the amplitude of the max amplitude you're supposed to feed into a TV's video input.

I really recommed the Ultra Simple... circuit, it's very cheap to build, works most of the time and won't damage any hardware.

[Yod@]

Thanks for clarifying that.

I still just use pins 13 and 14 connected together though - as you've pointed out, the logic signal is pretty high, but the upside of this is that I can also run the combined sync signals to SCART pins 8 and 16 for switching the TV to RGB.

I've used this on the cards I mentioned above without suffering any ill-effects, so I can safely say that it works for me. I also use it on my arcade monitor, and it works fine on that too.

I've just tested the cable using only composite sync, and the picture rolls vertically - so you're absolutely right about that. It was a long time ago when I tested out a composite-only sync cable, and I can't remember which card it was. Clearly I just jumped to the conclusion that it would work on other cards as well, so thanks for clearing that up as well.