So who wants to help me make a COMPONENT box for the DC?

Lyris · Post by **Lyris** » Fri Mar 24, 2006 3:23 pm

All right, this has been discussed before but never done. Time to put a stop to it. I am going to attempt it.

I have never touched a soldering iron in my life so that is something I will need to learn. In the mean time I'm gonna get my dad to help (how embrassing

)

I have some questions to ask for people who actually know what they're doing with electronics. My idea is to use the Silicon Chip online magazine's RGB to Component DIY box: http://siliconchip.com.au/cms/A_102648/article.html . I don't know what the quality is like, so has anyone constructed an RGB to Component converter using the idea from the site? (It needs a login but I posted the schematic - right term? - here: http://img482.imageshack.us/img482/2365 ... 2mg7de.jpg )

Now that device takes R,G,B video from a European style SCART connector and converts it to Y/Pb/Pr Component video. I'd be modifying it a little and hard-wiring Pins 14, 15 and 16 of the Dreamcast video output into where the inputs on that box would be. In addition since the DC outputs Composite sync on pin 10, I assume I could just pass that through onto the Y cable without modification to get the sync?

Or, in VGA Mode, is Composite sync output on the DC inactive? So I would have to somehow combine pins 8 and 9 (H and V sync) to get what I needed? Can anyone advise?

In addition, I'd also want to try and build in compatibility for games that won't boot when VGA Mode is on. I'd want to do a switch on the cable that would turn the box into "TV mode" just like the official VGA boxes. Doing that on my box would turn VGA mode off and pass INTERLACED RGB (like on a Euro-SCART cable) for conversion. So you'd still get 480i video over Component for non-VGA games.

Also please nobody ask "why not just use VGA" thanks

A lot of TVs are being produced without VGA inputs now and that probably isn't ever going to change. We need a solution for getting Component from the DC that doesn't cost $150 and need plugged in to the wall. The new Sony Bravia LCD I'm getting does have a VGA input, but I'd find it useful to feed the DC into one of the Component ports. And I don't have the moolah for another $200 transcoder

Thanks for reading! It'll be great if I actually get this to work and I'll share the results with everyone.

semicolo · Post by **semicolo** » Fri Mar 24, 2006 8:56 pm

I don't know if the composite sync is inactive, you'll have to test it.
Use a converter like this if it's inactive :
http://www.epanorama.net/circuits/vga2rgbs.html
You'll have to mix the sync with the luminance, maybe with :
http://www.tkk.fi/Misc/Electronics/circuits/sync_r.html, you can't just connect Y and sync together.

Sir Savant · Post by **Sir Savant** » Fri Mar 24, 2006 9:27 pm

why not just use VGA?

Lyris · Post by **Lyris** » Sat Mar 25, 2006 7:29 am

If you wanna buy me the trasncoder then sure

SuperMegatron · Post by **SuperMegatron** » Sun Mar 26, 2006 10:43 am

This is impossible for the most part. We had a tread on this about a year ago and I contacted a guy who built rgb out on his dc and asked for help. After a while we realized or more honestly he realized we couldnt build it for less then the cost of a vga adaptor 20 bucks and a vga to component hd adaptor 99 when you added in time and component costs.

rhubarb505 · Post by **rhubarb505** » Tue Mar 28, 2006 1:59 pm

Well, seems like it could be possible, and quite rewarding. The only problem I see is human error. Thats quite a circuit and quite small contacts on the motherboard for somebody who has never touched a soldering iron before, especially if you plan on making it internal.

But best of luck, hopefully this will be the definitive thread, either prove it possible or impossible.

Lyris · Post by **Lyris** » Tue Mar 28, 2006 3:09 pm

I don't plan on making it internal no, my plan is to use a standard VGA box and modify it into a Y/Pb/Pr output one.

This is the very first schematic I have ever stuck together. It's made from various parts. So don't laugh

As you can see it is not my own work - I need to make that clear - all I did was stick the parts together and assume what goes where.

Do you think this is worth building? Can you point out all the dumb mistakes I must have made?

The schematic I modified from Silicon Chip Magazine needed a 9v AC input for power. Can I just feed it the +12v from Dreamcast AV out pin 4? Apologies if this is a really stupid question - as you can tell I'm new to all of this modding.

semicolo · Post by **semicolo** » Tue Mar 28, 2006 8:37 pm

No you need AC input to get positive and negative supplies (with +12V CC, D2 will be blocked and you won't get your -5V)
Don't forget to tie grounds together, the schematic seems ok to me.

TheDumbAss · Post by **TheDumbAss** » Wed Mar 29, 2006 4:42 am

I forgot that component video wasnt avalible for dreamcast when I went to NYC last year. I ended up asking at 3 different japanese game stores for that cable and after the third one I broke down and bought an S-Video cable.

Though my TV isnt HDTV I can still notice the increase in quality from Composite to Component and also the difference between S-Video and each of the others. If this turns out to be a workable project I may have to try my hand at putting it together myself. The schematics look feasable but I'm not as much of an electrical engineer.

Somewhat related... but does the saturn offer Component video? If not could a similar SCART to Component conversion be done?

Lyris · Post by **Lyris** » Wed Mar 29, 2006 5:09 am

No the Saturn doesn't offer internal Component support. It was a standard for broadcast engineers only back then. I see no reason why this mod couldn't be done for the Saturn too though, but of course you would only get 480i video out.

Also remember the point of this mod is to get 480p video over Component from the Dreamcast. On flat panel displays this is a huge increase in picture quality from interlaced video. You should see Shenmue II running in 480p on a good LCD (like one of the Sony ones) - I had it hooked up back when I had my expensive VGA to Component transcoder and holy crap did it look good.

So Semicolo, is there no way at all to modify this schematic to draw power from the Dreamcast's AV port?

semicolo · Post by **semicolo** » Thu Mar 30, 2006 6:56 am

You'd need a switching inverter, something like : http://ca.digikey.com/scripts/DkSearch/dksus.dll?Filter
That's just an example, choose one that match exactly the power needed
Trouble with theses things, is they are noisy, they may add noise to the video signal.

Ex-Cyber · Post by **Ex-Cyber** » Thu Mar 30, 2006 1:44 pm

Couldn't that be "solved" (to the extent that noise is band-limited to frequencies above the video bandwidth) with careful application of filter capacitors on the regulator output, or am I displaying my gross ignorance of analog electronics?

semicolo · Post by **semicolo** » Thu Mar 30, 2006 5:55 pm

of course such chips need some capacitors to clean up the output, but filtering is just a matter of getting acceptable signal to noise ratios, I was just pointing out that dc converters are more noisy (in fact in higher frequencies) than linear supplies. Even with capacitors of multiple farads you still get noise when you redress 60Hz.

Ex-Cyber · Post by **Ex-Cyber** » Thu Mar 30, 2006 7:07 pm

Yeah, I guess I misremembered it and the main targetable property of the output noise was amplitude, not frequency (which I suppose is determined primarily by your switching frequency and any noise on the input). I really need to read up on switching power supplies again; I'm afraid I've forgotten most of everything useful about them.