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New Coleco RGB board?

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The Colecovision only had RF originally. This isnt exactly like those as they use a fpga or cpld with custom firmware. However it is more involved than just a RGB bypass board like the ones for the SNES. The colorspace is being converted from YUV to RGB.

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thanks! yeah I know the CV only had RF externally but was trying to figure out what it outputs internally. to reference a newer system the PC Engine had a standard RF out but it had RGBS available internally. I believe the Atari VCS only has RF externally but has Y/C ( Luma-Chroma / S-Video) internally.

 

So what you're saying is on the TMS9928A Pins 35, 36, and 38 output B-Y (Blue difference) Y (Luminance) and R-Y (Red difference), and that in this mod it is a simple color Transcode from Y,B-Y,R-Y to RGBs, which is a much simpler process than a from scratch digital to analog Encode which these other devices like the F18A, NESRGB, etc are doing, which basically bypass the entire native analog encoding process of the Colecovision video IC. Whereas the solution in this thread works with what the original Colecovision IC natively outputs and performs a simple transcode on. right?

 

Thanks!

Edited by panzeroceania

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There is a PAL board as well. I don't know if anyone ever tested it though. A few people said they were going to order them. Citrus put them up on oshpark if you want to make some.

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Would this work on the Adam Computer?

No reason that it shouldn't seeing as the CV board on an Adam is nearly identical... just rearranged a little.
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Just FYI, I am almost out of stock on these. I will be ordering more but making a few alterations to the board. The changes will not be require current owners to upgrade. They are mainly minor changes based on data I have compiled.

 

There also will not be a price change for the next revision. If anyone wants bare boards to build themselves, I do have a few bare boards of this current revision that I could sell without components.

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Thanks for the update mobiusstriptech! I'm looking forward to buying a board kit from your new batch.

 

Right now I broadcast an all homebrew Twitch livestream show using an RGB Atari 2600 and I'm looking to get into showing off the latest Coleco homebrew as well, in the best quality possible of course! :-)

 

Just FYI, I am almost out of stock on these. I will be ordering more but making a few alterations to the board. The changes will not be require current owners to upgrade. They are mainly minor changes based on data I have compiled.

There also will not be a price change for the next revision. If anyone wants bare boards to build themselves, I do have a few bare boards of this current revision that I could sell without components.

 

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New prototype boards should be here soon. I have a few Colecovision consoles to test these on so with any luck I will be ordering the new batch very soon.

 

On a different note, I have had 2 people report issues with green color bleed on white lines, specifically the lettering. It is most prominent in cases where a digital display and a scaler (Framemeister/OSSC) are in use but it might be visible on some PVM/BVM. In both cases there has also been an issue with screen brightness. If anyone has purchased a board from me and encountered this, please let me know. I am interested in finding a solution to this, if it is possible.

 

On one board I had to use a much larger value pot for green to drive the signal down to spec. It was seeing 1VPP with the 5k pot maxed out.

 

Again this has been limited to only 2 reports so far and the same RGB board does not exhibit the issue on a different Colecovision board. So I do believe it is the main board that is causing the heavy green saturation and dark image.

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As a small update. I have the newest revision prototypes in hand. These boards are currently in test and from my testing thus far they perform on par with the previous boards.

 

Now that being said, I have begun to make modifications to the circuit from what citrus originally put out. All of these modifications are based on my findings from all of the installs. I believe I have located the source of the green bleed issue, as well as the dark/narrow line issues that those consoles were displaying. I am currently investigating a few other minor things I would like to see changed or improved.

 

So no ETA on a new batch yet but hopefully in the near future.

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Boards ordered, so we will see if they work on a PAL coleco in about a months time :)

 

Did you (or someone else) try out the PAL RGB Boards yet?

Would like to mod mine as well...

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On 6/13/2019 at 10:43 AM, ongikong said:

 

Did you (or someone else) try out the PAL RGB Boards yet?

Would like to mod mine as well...

Not yet, but I hope to test them in 1-1.5 months period.

 

I panelized a batch of Citrus3000 psi RGB Boards 2 months ago, later ordered components to build at least 5 boards and stated to build them as I wanted to test it on my Colecovision and TI-99/4A PAL machines.

How fun was to discover on the meanwhile that the TMS9918A and TMS9928A are completely different and while the first does composite out, the second does luminance and color difference.

So I ended up with a batch of 5 ColecoRGB NTSC PCBs that I won't be able to use them and a batch of PCBs of the same variant. If anyone is interested, please, let me know, but have in mind that they are untested!.

It was my fault, next time I should read the project details from tail to end :(

Now I am decided to do a new PAL pcb prototype, among with the minidin header. Let's see if things goes better this time.

 

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1 hour ago, mobiusstriptech said:

Anyone can sell the colecovision RGB boards from citrus. The new boards I have been working on however, I have no intention of selling on eBay.

Okay, and the board can be fully assembled on my own.

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8 minutes ago, mobiusstriptech said:

Yes absolutely. Just keep in mind that whoever sells the boards is ultimately responsible for providing support. 

Okay, so unlike the 2600RGB board from etim whom is basically the AU site, citrus is possibly the US site.

BTW, if I install the RGB board for the Coleco, I have to get the components for the board to solder them all.

Other than that, there was a download option for that.

Edited by Retro_Game_Lover96

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Citrus does not have anything to do with the project anymore. He created the first revision and released it. I took over the project from him and have been actively working on it ever since. But ultimately, it is an open source project for anyone to work on/use.

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25 minutes ago, mobiusstriptech said:

Citrus does not have anything to do with the project anymore. He created the first revision and released it. I took over the project from him and have been actively working on it ever since. But ultimately, it is an open source project for anyone to work on/use.

Okay, so this can be purchased. 

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Finally I've been able to do the assembly of one PAL ColecoRGB board.

Unfortunately I ordered the 4066 on TSOP package and not TSSOP-14, so I had to do a workaround to have at least a proto finished.

By the way citrus3000psi states that this board is untested and should be used on own risk.

By the way I haven't seen anyone confirming that the PAL board works, so I'll cross my fingers...

 

 

15742021780904680400324830971554.jpg

Edited by Quickie

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1 hour ago, Quickie said:

so I'll cross my fingers...

Well I'm cautiously optimistic about it.  The two VDC chips have only a few differences between them and none of them affect color mixing at their stage of output.

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On 9/28/2018 at 11:15 PM, mobiusstriptech said:

As a small update. I have the newest revision prototypes in hand. These boards are currently in test and from my testing thus far they perform on par with the previous boards.

 

Now that being said, I have begun to make modifications to the circuit from what citrus originally put out. All of these modifications are based on my findings from all of the installs. I believe I have located the source of the green bleed issue, as well as the dark/narrow line issues that those consoles were displaying. I am currently investigating a few other minor things I would like to see changed or improved.

 

So no ETA on a new batch yet but hopefully in the near future.

From the way it looked to me the Citrus board was a surface mount clone of the RGB board I paid a guy $2K to create for me. Color line circuits ideally need variable resistance to adjust for differences in the VDP (I suspect this is from the aging of the chip)

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