Adding RGB to a TV - risks?

[elvis]

What are the inherent risks at a hardware level of using a device like the Ultimarc video signal amplifier to drive the RGB input inside a television directly?

I'm not talking about an external RGB connector (like SCART or BNC adaptors, etc), but actually removing the RGB+Sync plug from the chassis to the tube, and pushing 15KHz RGB information directly (say via an ArcadeVGA or Linux+AdvanceMAME)?

Assuming all of the voltages are right, would this work?  Or would it put the connecting device (say a PC) in danger?  Or is this something that varies from TV to TV?

The reason I ask is due to the fact that is simply impossible to find TVs with RGB inputs any more, and in this country RGB monitors cost a fortune (mainly due to the fact that nobody makes them locally, and they always need to be imported which attract huge import duties and taxes), or you need to risk dodgey broken gear off eBay. 

If bypassing most of the TV's image signal generating hardware is easy enough, I'd give it a go, assuming there's little risk of taking out a PC or video card in the process.

[SirPeale]

People have done it before by finding what parts of the TV chassis handles the RGB output, but you can't just hook the RGB up to the yoke.

[elvis]

but you can't just hook the RGB up to the yoke.

What type of signal/voltage does that usually send?

[RayB]

How does Component input differ from RGB?

[elvis]

How does Component input differ from RGB?

When most people say "component" they are referring to YCrCb (or YUV here) component:
http://en.wikipedia.org/wiki/YUV
http://en.wikipedia.org/wiki/YCrCb

("Component" of course means just splitting any signal into smaller components, but the term has pretty much gained the accepted standard of meaning YCrCb these days).

RGB by far is the easiest signal to generate from arcade boards, PC hardware, etc.  Conversion from RGB to YCrCb requires transcoding, and often means an expensive inbetween adaptor.  And no matter what people say, I still think RGB looks miles better.

I've seen a few links around the web referring to people who have hacked RGB inputs into cheap TVs with amazing results, but the documentation on how they managed this is sketchy at best.

Here's a good example:
http://www.porkrind.org/arcade/tv-hack.html

And I quote: "We hooked up the RGB outputs from the game board right to the guns on the back of the CRT".  No pictures, no details, no schematics, nothing.  I'm just wondering if it really is that easy?

I'm curious to know what signals the 4 wires going from a TV chassis to the neckboard actually carry, and if there's some uniform spot where RGB inputs can be added to a television to convert it into a cheap RGB monitor.  I don't care if I have to give up the ability to use any other input or even watch TV on that unit, as all I care about is a source for nice cheap RGB monitors.  With 52cm (21") TVs appearing here in Australia at $150 a pop (US$110) that sure beats the hell out of the $900 WG monitors of the same size people are trying to flog off here.

In particular I'd like to hear what the monitor techs have to say.  I'd really like to know if this is even remotely possible, or if I'm just dreaming of things that can never happen.

[tisurame]

I'm using a NTSC TV with Component Video through a TC2000 transcoder.
 
http://www.crescendo-systems.com/transcoder.html

This transcoder only convert the RGB signal to Component YPbPr. It's just a color-space conversion, nothing else changes. So, it will not mess with resolution and horizontal and vertical frequencies. So you will be free to use ArcadeVGA or Advmame.

This transcoder was made to use with PowerStrip, for those that want to create a HTPC.

[dennis808]

here are some oics of the circuit you mentioned:




And the hacked TV's


I hope you succeed, 'cos thids would provide a really good alternative.
(Thankfully, I live in Europe, where all cheap TV's have a SCART input with Composite, S-Video and RGB input)

[elvis]

I'm using a NTSC TV with Component Video through a TC2000 transcoder.
 
http://www.crescendo-systems.com/transcoder.html

This transcoder only convert the RGB signal to Component YPbPr. It's just a color-space conversion, nothing else changes. So, it will not mess with resolution and horizontal and vertical frequencies. So you will be free to use ArcadeVGA or Advmame.

This transcoder was made to use with PowerStrip, for those that want to create a HTPC.

A converter of decent quality (ie: one that ONLY does colourspace conversion, and doesn't force output modes into PAL, which all the cheap ones do) you have to spend a bit of money to get them locally, or again import them which costs a fortune.  Buying a $150 TV is totally defeated if I then have to buy a $200 YCrCb converter to use it the way I want.  I want this to be a budget-driven experiment.

here are some oics of the circuit you mentioned:

I hope you succeed, 'cos thids would provide a really good alternative.
(Thankfully, I live in Europe, where all cheap TV's have a SCART input with Composite, S-Video and RGB input)

I saw those images, but they aren't exactly clear on how the mod was acheived.

I've emailed the author of the site, and hopefully there'll be some response from him.  Otherwise I'm going to have a chat this week with a few monitor repair guys I know, and see if they can offer some general advice.  At this stage I'm still trying to work out if it's even possible, let alone how to do it in a generic way that can be applied to most TVs.