Colecovision, Atari 7800 and Intellivision - RGB!

[bacteria]

Well guys, research is a wonderful thing, yes?

 

I originally bought a UK (PAL) ColecoVision console after reading somewhere you could tap off the video chip to get composite video. Turned out to be complete rubbish, it didn't; in fact, the system only outputs a weak signal of component which was no use and needed conversion anyway. So, I bought a Dina 2-in-1 console which was the Telegames version of the ColecoVision after they bought ColecoVision out from receivership: that console was utter rubbish, and in fact died after only a little use, which was £70 down the toilet. I read that the NTSC chip could output composite as standard and you could swap the chips, so after some dremelling, swapped the chip from the Dina to the UK ColecoVision (as was the right chip) and I got composite, although rainbow effect, in other words, objects had different colours on the edges. So, asked in a couple of forums and they suggested amplifying the signal, which I did and made no difference; also, their reference to using ground in the diagrams caused problems - any connection to the composite signal line to ground even indirectly stopped the console outputting anything. In fact, one of my screens has amplification built in and showed the composite with the rainbow effect, the PS1 and PS2 screens I have showed nothing. I therefore deduced that the output from the screen that did output was in effect the best you could get with amplification. Asked again in forums, the "it's a 1978 chip, that's about as good as they were".

 

So, all these reference were dead ends. I spent £35 on a UK ColecoVision, £70 on a Dina and got two dead consoles and a stack of games which I spent about another £30 on. Great. Whoop!

 

More research, one last chance - turns out that ColecoVision made two versions of their consoles for France (SECAM they use, not PAL or NTSC) and one of them could output SCART... SCART means RGB and composite after all - built in, and placed in the position on the UK board where there was just a gap, and less stuff on the board generally. Bought one off ebay, cost around £40 I think it was.

 

Just tested the SCART ColecoVision console, works fantastically - very crisp, colours well defined, beautiful! Also, plays all my PAL cartridges (although I did need to open one up to use a pencil eraser to clean the traces first).

 

So, I have also won a French SCART Atari 7800 now, about £43 it cost me; when that arrives, it will also be RGB! To those that don't know, there is an Atari 7800 composite mod process but gives only "ok" results, there is one that costs about what I paid for my console that does S-video, good, but variable (judging from the posts I have seen about it); RGB of course is the best you can get.

 

I bought a composite mod for the Intellivision which I haven't installed yet (will do); however turns out you can buy also, guess what i'm going to say lads - a French one with SCART! (bit late now), although they cost a fair bit to buy (about £70-£100).

 

So guys, great tip for you - if you want RGB or composite for your Intellivision, ColecoVision or Atari 7800 experience, buy a French machine! (you will need PAL games of course, the Intellivision will play any region as standard but the others don't).

 

Pretty interesting stuff, eh!

[Kr0tki]

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Edited April 23, 2010 by Kr0tki

[bacteria]

Oh well, I thought you guys would have been interested! *shrugs*. BTW, the ColecoVision looks nice but appears to have no sound, so needs audio tapping off the chip I presume.

[mimo]

The Colecovision will also play games from any region with no issues, and the maxflash 128-in-1 cart works fine too. There are no problems with sound, works fine on my 2 SECAM colecovisions (actually they output a PAL signal not SECAM) so you should not have to do any mods to get sound.

As for the SCART 7800's, they also output a PAL signal. I have had 3 of these, one of them would not work with my CC2 but the other two are fine.

[RGB_Gamer]

The Colecovision will also play games from any region with no issues, and the maxflash 128-in-1 cart works fine too. There are no problems with sound, works fine on my 2 SECAM colecovisions (actually they output a PAL signal not SECAM) so you should not have to do any mods to get sound.

As for the SCART 7800's, they also output a PAL signal. I have had 3 of these, one of them would not work with my CC2 but the other two are fine.

 

 

Preppie,

 

That's awesome news. I have a Cuttle Cart 2 for the 7800, and I am currently looking for a French 7800 with SCART. Seems ebay france is the only place to find them. Now you said that two of your French 7800's were incompatible with the CC2. Have any idea why? NTSC games on the CC2 work on your French 7800 with no problems?

Edited June 4, 2010 by RGB_Gamer

[mimo]

Sorry for the delay, I think the problem with the CC2/Peritel 7800 was the timing circuit added by Atari to improve compatability with some games

NTSC games are the same as playing NTSC games on any PAL system, a couple work, some have the wrong colours/graphics problems and som just dont play at all.

But as you have a CC2 it's no problem

[gdement]

Is the picture from a French RGB 7800 any better than an SVideo mod? The native outputs from the Maria graphics chip are luma, chroma, and sync. So RGB isn't a native output, it would have to be produced by conversion. The native outputs are much closer to SVideo.

The only advantage I can see for RGB is that the sync would only be mixed with 1/3 of the signal (sync+green I assume), instead of 1/2 of it. (luma+sync are mixed on svideo). I don't think the separation of the color channels would help, since they were combined at the chip output and are only artificially separated.

 

The ideal would be separate luma, chroma, and sync connectors, but that's not a standard. I wonder if pro monitors support that type of hookup.

[kool kitty89]

You can tap composite video from all of those systems... Actually you can for any system that outputs RF or S-video (unless RF is handled in an external module with the console outputting RGB or such -though in those cases it's usually already outputting composite of Y/C natively, but sometimes it's RGB only -or Y'PbPr, but I don't think there's any example of that being output externally on such old computers/consoles)

 

Now, composite (and/or Y/C) may not necessarily be output by the main video chip, but an external transcoder (usually for RGB, but in the CV's case, Y'PbPr). Almost every platform using RGB colorspace does that while chroma/luma palette VDCs tend to output composite and/or Y/C natively and that was true for the TMS9918/9918A, native composite only, but the 9928/9929 models output Y'PbPr to facilitate external transcoding for different regional video standards (PAL, SECAM, and NTSC using different color carriers -s well as others like PAL-M). One cool thing about that is that you can get component out of it, but it's weak and needs amp/buffering. (then again, RGB would be far more useful for SCART users and was far more common in general -and would have stayed that way had DVD players opted to push RGB in the US instead of going with Y'PbPr, but I digress)

 

 

For a platform that outputs RF, but you don't necessarily know where the source audio and video are on the board, one option is to simply go straight to the solder points on the RF modulator as those should include composite video and analog audio (almost always mono for game consoles -VCRs output stereo RF I think as may some external RF units). In that case, Audio is often fine, but composite video may or may not need additional buffering. (normally invloving a capacitor and resistor, and I think it varies depending on the case, but 220 uF caps tend to be fine -lower may be OK too- and a 33-75 ohm resistor -that's generally for sync stability and the lower the value you can get away with, generally the brighter/sharper the video, at least in the contexts I'm familiar with, though you may end up with high saturation or brightness in some cases if you can't adjust the TV to compensate)

[RGB_Gamer]

I finally got a French SCART/Peritel Atari 7800. I connected it to my RGB monitor and the results were not bad.

 

See this post about my SCART to Component adapter:

 

http://nfggames.com/forum2/index.php?topic=3580

 

I connected my French Atari 7800 to this adapter and to my TV, but alas, the picture rolls. Every other system I have works

just fine with this adapter. I don't know what the problem is, so I can't comment on the French 7800 with this adapter.

 

I will post pics of it with my RGB monitor soon. I will be getting a French SCART/Peritel Colecovision soon, so I will let you all know about that

Edited June 27, 2010 by RGB_Gamer

[kool kitty89]

So other 50 Hz consoles (PAL/SECAM) work fine on the TV, but just not the French 7800?

[Kakaboy]

Well guys, research is a wonderful thing, yes?

 

I originally bought a UK (PAL) ColecoVision console after reading somewhere you could tap off the video chip to get composite video. Turned out to be complete rubbish, it didn't; in fact, the system only outputs a weak signal of component which was no use and needed conversion anyway. So, I bought a Dina 2-in-1 console which was the Telegames version of the ColecoVision after they bought ColecoVision out from receivership: that console was utter rubbish, and in fact died after only a little use, which was £70 down the toilet. I read that the NTSC chip could output composite as standard and you could swap the chips, so after some dremelling, swapped the chip from the Dina to the UK ColecoVision (as was the right chip) and I got composite, although rainbow effect, in other words, objects had different colours on the edges. So, asked in a couple of forums and they suggested amplifying the signal, which I did and made no difference; also, their reference to using ground in the diagrams caused problems - any connection to the composite signal line to ground even indirectly stopped the console outputting anything. In fact, one of my screens has amplification built in and showed the composite with the rainbow effect, the PS1 and PS2 screens I have showed nothing. I therefore deduced that the output from the screen that did output was in effect the best you could get with amplification. Asked again in forums, the "it's a 1978 chip, that's about as good as they were".

 

So, all these reference were dead ends. I spent £35 on a UK ColecoVision, £70 on a Dina and got two dead consoles and a stack of games which I spent about another £30 on. Great. Whoop!

 

More research, one last chance - turns out that ColecoVision made two versions of their consoles for France (SECAM they use, not PAL or NTSC) and one of them could output SCART... SCART means RGB and composite after all - built in, and placed in the position on the UK board where there was just a gap, and less stuff on the board generally. Bought one off ebay, cost around £40 I think it was.

 

Just tested the SCART ColecoVision console, works fantastically - very crisp, colours well defined, beautiful! Also, plays all my PAL cartridges (although I did need to open one up to use a pencil eraser to clean the traces first).

 

So, I have also won a French SCART Atari 7800 now, about £43 it cost me; when that arrives, it will also be RGB! To those that don't know, there is an Atari 7800 composite mod process but gives only "ok" results, there is one that costs about what I paid for my console that does S-video, good, but variable (judging from the posts I have seen about it); RGB of course is the best you can get.

 

I bought a composite mod for the Intellivision which I haven't installed yet (will do); however turns out you can buy also, guess what i'm going to say lads - a French one with SCART! (bit late now), although they cost a fair bit to buy (about £70-£100).

 

So guys, great tip for you - if you want RGB or composite for your Intellivision, ColecoVision or Atari 7800 experience, buy a French machine! (you will need PAL games of course, the Intellivision will play any region as standard but the others don't).

 

Pretty interesting stuff, eh!

 

Hey that sounds reassuring . I have just bought a french SECAM Intellivision . Im in Australia and we use the same PAL format you do in England . It has the standard RF , Will I be able to just plug that straight in and get it to work , or will I need to do the RGB mod ?

 

Cheers

[Tighe]

Hey Bacteria, Did you take any pictures of the inside of your French CV? I wonder how hard it would be to modify a USA CV to output RGB.

[nanochess]

Hey Bacteria, Did you take any pictures of the inside of your French CV? I wonder how hard it would be to modify a USA CV to output RGB.

I remember someone sent me pictures of the inside of a French SCART Colecovision (I don't saved copies), it has an extra board in the inside that I believe is for the RGB output (in the SCART connector)

 

Also I think there is a chance of replacing the TMS9929 video processor (PAL) with a TMS9928 video processor (NTSC) to get NTSC RGB output.

[Tighe]

I remember someone sent me pictures of the inside of a French SCART Colecovision (I don't saved copies), it has an extra board in the inside that I believe is for the RGB output (in the SCART connector)

 

Also I think there is a chance of replacing the TMS9929 video processor (PAL) with a TMS9928 video processor (NTSC) to get NTSC RGB output.

 

Thanks! I found this, see at the bottom:

 

http://nfggames.com/forum2/index.php?topic=4396.0

[nanochess]

 

Thanks! I found this, see at the bottom:

 

http://nfggames.com/forum2/index.php?topic=4396.0

 

Yep, the CBS Colecovision PAL and SECAM should be using the TMS9929 video chip (50 hz) and replacing it with TMS9928 would make it NTSC (60 hz).

 

There is a further byte in BIOS in location $0069 that should be changed to 60 decimal.

 

Anyway I don't know if anybody has tried to do this mod.