RGB scrolling problem

[bacteria]

Ok, on my TurboGrafx project, I have the system running on composite at the moment, which is fine; however I know the TurboGrafx (UK version) I use converts RGB (NTSC) into composite (PAL), via a Sony CXA1140P chip, although I can't find any datasheets on it.

I hooked the RGB and C-sync and ground wires to my Logic 3 screen, as it has a PAL and NTSC switch for the RGB - on PAL setting I get corrupt lines (no surprise) while on the NTSC setting I get the picture nice and crisp, however the image picture scrolls and doesn't hold on the screen like it should. This makes it unusable.

Does anyone know how to stop the screen scrolling? I tried a 220uf capacitor on the C-sync line, and a 100uF too, made no difference.

Anyone got ideas - otherwise I will use composite of course (which works fine); however, would be nice to use RGB.

[MegatronUK]

Hi, all the PC-Engine/TG models output RGB from the same Hu chip (I did the mod to my US Duo years ago) - You should be able to tap straight in to it directly, rather than messing with the encoder which they put on the abomination of a console they made with the PAL TG16

http://www.gamesx.com/rgbadd/duorgb.php

[MegatronUK]

Actually, thinking about this - the PAL TG16 runs at 50Hz (as expected), I wonder if that is making things more difficult than it needs to be. How far how you gone? It might be easier to buy a cheap US TG16 from ebay; they're faster and the RGB mod works for definite at 60Hz.

[bacteria]

That was the site I got my info for the RGB.

I was tapping straight off the chip. As mentioned, colours good, definition good, but getting scrolling for some reason.

Haven't tapped to the encoder, as I imagine it just takes the above signals and re-works them.

Perhaps, as you say, as the system runs 50Mz it might be the issue? Only other thing I can do is try it in an NTSC PSone screen (I have PAL and NTSC ones), in case that makes any difference.

TurboGrafx are quite expensive, I got a cheap one (!) at about £45 - you can easily pay double that. Got quite a few games for it now - it is a very good system; I personally rate it quite highly, from what I have played on it so far.

No, rather advanced in project, relocated the game port entirely, cut the board to about 60% of its original size to get it to fit into my case, and got it working on US and Jap games.

[MegatronUK]

The PC-Engine/Turbo is a fantastic system - there's some amazing arcade conversions and it has probably the best shooter library out there. Plus, it has the definitive version of the best computer pinball game ever released: Devil Crash (potentially the best video game theme tune ever? I think so!)

[grahf]

Perhaps you should try the RGB amp from the gamesx pages. But only build one for the sync line. Its a possibility it's just not strong enough for your screen.

[bacteria]

Yes MagatronUK - the PC-Engine/TurboGrafx is a very good system indeed. I came across it via emulation a few years back - as typical for me - you know these companies like Nintendo, Sony etc moan about people using emulation and "robbing" them of sales - people like me only played games via emulation first, then got into consoles in the first place, then not only buy lots of old games and systems but new ones to; so those gaming giants I say a big "Pah" - if it wasn't for emulation I wouldn't have got into consoles and therefore they have gained profit from me (and lots of sellers as I have replaced virtually all my emulation games with proper originals now!)

So, MegatronUK - apart from the titles I list below, which ones do you really rate as great titles - I will look into them and see what else I want to buy.

Anyway, back on subject, the system has some truly excellent titles for sure; and many that suck. My collection so far, over the last weeks of e-baying are:

Alien Crush
Break-in (jap)
Bomberman (jap)
Bomberman '93 (jap)
Bomberman '94 (jap)
Cratermaze
Dead Moon
Final Lap Twin (jap)
Galaga '90
Gradius (jap)
Military Madness
Power Golf
R-Type 1 (jap)
Side Arms (jap)
Space Invaders (jap)
Salamander (jap)
Vigilante

Played some of these briefly on an emulator so I didn't buy crap titles; others I searched on YouTube for videos of the games. That is my only interest in emulators now - to decide if I want to buy the proper game or not. Some of the games above are quite rare. I spent between £3 and £14 on each one; some took several bidding attempts on e-bay to get the title at a fair price!

I think the TurboGrafx / PC-Engine system is underrated - it came out to battle the NES, and frankly it beats it with hands behind its back. I put the system personally on even par with the SNES in terms of graphics, game quality, etc - maybe slightly higher: and of course, really thin game carts!

Devil Crash I believe is the follow-up to Alien Crush as a pinball game - personally though I think the best on any platform is Psycho Pinball on the Megadrive/Genesis.

graphf - you might be right, although I haven't checked to see if the signal is strong enough for the PSone screen - might be it is, don't know.

This is the schematics from the site - as you say, the C-sync is all I probably need.

In the diagram, what does the "777" refer to - is that grounding??



BTW - spray painting my case backing at the moment; put on about a dozen coats so far since last night; painting it red - yes, red - and it is taking a lot of covering to change the medium grey into red! (getting there, a few more coats will do the job!).

[MegatronUK]

Got some good games there - Bomberman 93 and 94 are especially good

Some more suggestions? Any of the Star Soldier series (Super Star Soldier, Final Soldier and Soldier Blade <- the best one, IMO), can't go wrong with Splatterhouse, any of the Bonk/PC-Genjin series (he was the mascot for the system after all!), Image Fight, Twin Bee, Parodious, Turrican, Metal Stoker, Raiden, Darius, W-Ring. There are some good RPG's, but a lot of them tend to be Japanese-only releases apart from the big ones like Neutopia and Dungeon Explorer.
If you want a fighter, then the best one on the system (and the only one on Hucard, IIRC) is Streetfighter 2 Championship Edition (you may want to add 6 button support to your portablised-TG16 for this game)

If you had a CD capable system there'd be a whole boat load of others

[bacteria]

Got a couple of these on e-bay watch at the moment! You mentioned a couple of games I haven't heard of, will look into them!

Didn't like Splatterhouse from the videos I saw on it, looks rather repetitive; the Bonk game looks like a Mario-wannabe; not into fighter games (eg Streetfighter). Not having the CD version as it would make the system too big; anyway, the best selling feature of the HUcard is its sheer smallness - better than CD's!

[bacteria]

No, just tried an NTSC PSone screen, the signals are not great, RGB can't register well and the image still scrolls.

I will try and make one of these circuits above, but may well just stay with composite at this rate. As the RGB and C-sync wires are connected to the chip, I can easily experiment now or later.

[eagle5953]

BTW - spray painting my case backing at the moment; put on about a dozen coats so far since last night; painting it red - yes, red - and it is taking a lot of covering to change the medium grey into red! (getting there, a few more coats will do the job!).

Red? I thought this project was going to be Batman-inspired...

[bacteria]

No, decided not to in the end, would have made the system larger than it needed to be, screen would have looked a bit small and themes are a bit geeky. Also, I want to have a bank of systems I made using my same case boxes - uniformity.

[eagle5953]

Ah, OK. Your case will look awesome in red, btw.

[bacteria]

Red and black!

Thanks!

[bacteria]

Interestingly, I output the composite signal through my PS2 screen and also a PSone screen at the same time - the PS2 screen, which is normally "ok" looks very good and better than on the PSone screen. On the PSone screen, I get the usual composite issue - reds a bit strong. This is typical in a scenario when RGB makes it worthwhile doing, and as it says in the link above, the RGB mod is quite stunning when done.

So, taken the plunge, have the capacitors, a 300 ohm resistor but not the 10 ohm and 75 ohm resistors, so got them ordered via e-bay with some of the quoted transistors.

I have two questions - please reply - which is right:

1)
=

or

2)
=

And also, what is - is that ground???

Is this a 10uf capacitor: I have some 10uf capacitors, 25v - I presume these are ok?