Sony Trinitron with composite/s-video only. Any way to hack a scart/RGB input?

[konp]

So the same TV I made a thread about a little while ago asking about universal chassis compatibility - go check that thread out for the TV particulars. Don't worry, you won't have to search far.

I've done some googling and there's a few vague guides online talking about hacking an RGB input into an NTSC tv. However, there's scant details on exactly how to achieve this. One guy fed his signal into the OSD pins on his TV's video processor, and it turned out ok-ish.

Anyway, on my television, I've located on the board an empty component input - as in, there is a spot there to wire in a connector, but there is no connector. Now I've read that possibly the component input of the chip may actually be disabled in its ROM as it wasn't standard on the model TV I've got, so it was turned off in a way that the end-user can't undo.

I know from experience that the S-video input on this TV isn't too bad, as far as they go, but honestly, I'd like to get the most out of the tube as possible if I can't just stick a unichassis on it. I'm aware it'll involve soldering, desoldering, possible rewiring, addition of resistors, etc. That's fine, I don't expect this to be "simple", but definitely something that's achievable with a bit of work.

Now from what I can determine, the input voltage for signals is a flat 1V on this TV. I know that most VGA cards these days output 1V signals. Would I be able to sever the RGB lines that feed the guns from the TV board, and connect them directly to a signal outputted from a VGA card? As long as I have something plugged into composite or Svideo on the back, it should just use the sync signals from that, yeah?

I've got the relevant service manuals with schematics of all the boards (that's how I managed to locate the unused component input) and can take as many photos as needed to make this more easily answered. And if it turns out I'm stuck with S-video then that's fine too. I'd just like to know one way or another if it can be done with relative simplicity.

[konp]

So I'm guessing from the lack of responses that either nobody knows, or I'd be in above my head and it's not worth doing.

[adder]

someone like rob (rcadegaming) would be good to answer this but i dont know how often he is around there days.
i'd say its probably impossible to do, and if it isnt it would be quite a mission....certainly no easy job.

[rCadeGaming]

It's not worth it.  You could get a better TV with a component input and an RGB to component transcoder for under $100.

[konp]

It's not worth it.  You could get a better TV with a component input and an RGB to component transcoder for under $100.

Good answer. Concise and gave me exactly what I needed. Thank you.

With a VGA to component/composite/svideo/RGB board, I'm confident this TV will look decent enough to use as a monitor. It's a trinitron, and they do have pretty spectacular quality on even the low-end inputs.

[rCadeGaming]

There will be an enormous difference in quality depending on whether you have a "converter" or a proper transcoder which only translates colorspace and doesn't apply any scaling.  See this post:

http://forum.arcadecontrols.com/index.php/topic,121491.msg1392896.html#msg1392896

[konp]

There will be an enormous difference in quality depending on whether you have a "converter" or a proper transcoder which only translates colorspace and doesn't apply any scaling.  See this post:

http://forum.arcadecontrols.com/index.php/topic,121491.msg1392896.html#msg1392896

How about something like this?

http://www.ebay.com/itm/VGA-to-RGBS-CGA-AV-S-video-PC-to-TV-arcade-video-game-/260705997170

I did a search for transcoders and didn't come up with many, converters come up with things similar to the above. I couldn't find any that said one way or another if they performed scan conversion (It's my understanding that I DON'T want a scan converter?)

[rCadeGaming]

No, if you read the description that definitely converts a range of resolution, 480p and up, to either 480p or 480i.  Neither of those outputs are suitable for 90% of the games in MAME.

Did you read the post I linked to?  Those are my recommendations.  The only thing I can possibly tell you about anything else will be either "I know it won't work well based on the description" or "I don't know without testing it."

Also, in your first post, you shouldn't tell people we have to search around to understand which TV you're talking about.  If you won't retype that info you could at least link to that post. 

[konp]

Did you read the post I linked to?

You mean the one that recommended SCART to Component, and RGB to Component? Because I fail to see how they would work when I specifically stated I want to go from RGB (preferably via VGA port) to S-video, in lieu of being able to somehow utilise the "spare" board points for component input on my television.

Here's the post with the television details, and if need be, I can take photos of the chassis boards and schematics as well.

It's probably also worth mentioning that I don't care so much about getting the games to run at their "proper" resolutions and all that. I'm used to playing on an LCD screen, so I'm used to 60hz and 1600x1200 res. If I was using a different TV (i.e. one that could take a unichassis or had component inputs already) then I'd probably go down the route of getting everything to run with custom resolutions and vertical refresh rates.

[Jack Burton]

It is worth the time to get the "right" resolution.  It will look better even if you use a lower quality connection.

I'd take 240p/composite over RGB/1200p scaled any day.

[konp]

It is worth the time to get the "right" resolution.  It will look better even if you use a lower quality connection.

I'd take 240p/composite over RGB/1200p scaled any day.

Well if I can find a VGA to Svideo transcoder that doesn't scale, I'd be happy to use that. Seeing as the TV isn't compatible with a universal chassis, that's not an option (thanks, Sony), and it doesn't have native SCART or Component inputs (even though it looks like the A-board has a spot for it).

[rCadeGaming]

You mean the one that recommended SCART to Component, and RGB to Component? Because I fail to see how they would work when I specifically stated I want to go from RGB (preferably via VGA port) to S-video

You're right, I kind of spaced on the requirement of your current tv barring the mod, BUT... there is no reason you need to cling to that TV as your only option.  Where do you live?  You can probably get a more appropriate TV with component inputs on Craiglist for under $50.  Look for a KV-27FS120.  That's what I use and I even have gotten some on CL for free.

[konp]

You mean the one that recommended SCART to Component, and RGB to Component? Because I fail to see how they would work when I specifically stated I want to go from RGB (preferably via VGA port) to S-video

You're right, I kind of spaced on the requirement of your current tv barring the mod, BUT... there is no reason you need to cling to that TV as your only option.  Where do you live?  You can probably get a more appropriate TV with component inputs on Craiglist for under $50.  Look for a KV-27FS120.  That's what I use and I even have gotten some on CL for free.

Nah, all good.

I'm in Australia, so I'd be looking at Gumtree, not Craigslist.

The reason I'm fixated on this TV is because it's a good TV, basically. The picture quality is fantastic even on the low-qual inputs. When I first connected a DVD player to it via S-video my eyes almost bugged out of my skull at the difference between that and composite. I paid a fair bit for it when I got it, and I'd very much like to get good use out of it.

[rCadeGaming]

That is because the DVD player had a decent video encoder that could make a very clear picture through S-video that's almost as good as what you'd get with component, and the DVD was designed to be viewed in 480 lines.  You will have a hard time getting those kind of results from a computer because these converters and TV-out ports have poor cheapo encoders that result in a less clear picture, which is then further compounded by the fact that they are locked into a resolution that is completely wrong for these games.  There is a world of difference between VGA transcoded to component in native res ~240p and VGA "converted" to composite/s-video scaled to 480i.  The former is a clear representation of what the game is supposed to look like, scanlines intact.  The latter is blurrier, lacks scanlines, and in most cases is unevenly scaled.

[konp]

That is because the DVD player had a decent video encoder that could make a very clear picture through S-video that's almost as good as what you'd get with component, and the DVD was designed to be viewed in 480 lines.  You will have a hard time getting those kind of results from a computer because these converters and TV-out ports have poor cheapo encoders that result in a less clear picture, which is then further compounded by the fact that they are locked into a resolution that is completely wrong for these games.  There is a world of difference between VGA transcoded to component in native res ~240p and VGA "converted" to composite/s-video scaled to 480i.  The former is a clear representation of what the game is supposed to look like, scanlines intact.  The latter is blurrier, lacks scanlines, and in most cases is unevenly scaled.

Is there such a thing as a VGA to S-video transcoder?

[rCadeGaming]

I can't say no categorically, but not any that I've found. 

A transcoder means a device that just translates colorspace information, leaving resolution alone.  When going between RGB and YPbPr component this is easy as the two are nearly equivalent, they just communicate colorspace a little differently.  The problem with converting to s-video or composite is that a clock frequency is needed to encode the color signals to a more compressed format, so the horizontal frequency of the output must be synchronized to the clock frequency.  A clock frequency designed for the NTSC standard (480i@60Hz) is generally used because your TV will work with it and it is expected that it will be appropriate for your content (in PAL territories, a different frequency may be selected for 576i@50Hz).  If the input signal doesn't match the correct standard it has to be scaled first.

Old consoles can output non-standard resolutions composite and s-video because they either lock horizontal frequency to the NTSC or PAL standard or they have non-standard encoder clocks.  Arcade PCB's output RGB video signals so encoding wasn't even a concern.  There are hundreds of different native resolutions and vertical refresh rates among the games available in MAME.  As long as you held the horizontal frequency from the PC relatively constant, it might work with an an encoder capable of accepting non-standard timing values without scaling them.  This isn't impossible but I don't know if it's been done.

Long story short, if you want the best results I think you just need to get on Gumtree and get something with component inputs.  Just make sure that it CAN'T display 480p or higher, as CRT's that can do so will typically upscale everything to that resolution before displaying it.  You wan't to be able to see the real ~240p these games are meant for.