Nintendo 8bit-rgb, finally! but..

Started by Rockard, December 10, 2003, 02:51:47 AM

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Yep, finally I have successfully assembling these things:

* 1 US NES
* 1 French NES (scart cable and socket)
* 1 playchoice chips (well, got 3 cheap on ebay as the boards were "broken" =)

to a wonderful RGB-outputting NES system : )))

Anyway, as I now have played around a bit with this blissing thing,
I have noticed that some colors just seems too bright to look correct.

Most notably, the brown color nearly always shows up too bright.
Maybe this is how the colors were hardcoded into the playchoice-chip?
For example, look at the hair and the surroundings in Kid Icarus(below). It's darkbrown using a/v-nintendo, in rgb it just is too bright.

And some colorcombinations just looks weird now in other games,
compared to a/v. And usually it's the same reason, brown is to bright.

Maybe the colormap in the playchoice is different from the colors in an
ordinary nes-chip?

this is the booster that was used in my nes:

I'm not that good at complicated technical stuff actually(my brother assembled my rgb-nes using my instructions), but maybe the colorbooster-thingy makes the signal to strong, making colors to bright?

Adjusting the gamma would be ideal, I think.

Anyone have some suggestions/experiences?



Since all the colors seem to be slightly askew try adding some pots to the rgb to adjust the colors, (that would work right?)  


Since red and green make brown, try lowering these levels.


You may also be seeing a side effect of RGB, which is increased colour purity.  NTSC encoding does strange things to the colour, which is why you have a TINT control (more important on older TVs).  RGB has no use for this, so be careful you're not trying to match the WRONG colour.

Put another way, maybe the RGB signal is right, and the NTSC one is wrong?  Try an emulator, see how that looks.


Well, actually the "a/v" picture from my first post comes from a palsystem, if that matters. But a ntscsystem looks the same anyways.. as I have noticed.

Anyway, below is a pic I found from a emulator-screendump.

As far as I know, the colors from the nes-system is hard to extract for emulator purposes, so I think it would be pointless to compare to an emulator.
But well, I don't think they are _that_ far off anyway..

But really! I don't think that an rgbsignal converted to an a/v signal would be that much difference, don't you think?

I'm I alone on this mod? Has not anyone else performed this??

How come the gamesx-site still doesn't mention this playchoice-hack as the way to give nes rgb?


QuoteHow come the gamesx-site still doesn't mention this playchoice-hack as the way to give nes rgb?
I don't want to show people how to do it until I can get a PC for myself.  =)


Have a look at this:

[...] switching the PPU for the Playchoice 10's will lead to palette differences and some graphical glitches.


Crap! :(

Can't someone manifacture a great working rgb-ppu for us all rgb-nes geeks??  :/

Blagh.. well, I'm happy I got as far as I did.

Since not all games works with this chip, maybe someone can assemble a
list of the nesgames that actually work good with this chip?

I'd love to do it, but I mostly have pal-games since I live in Sweden...
which probably will screw up the compability even more..

Anyway, does anyone know if Castlevania 3 and Kirbys Dreamland works with the chip?
Since CV3 have this extra thingy-enhanced grafixchip, looking at this in rgb would be essential. And well, Kirby is also nice and colorful.. 8)


Playchoice PPUs RP2C03B hold the same palette like the Famicom Titler PPU RC2C05-99.

The colors are correct and looks the same quality like the Famicom-Titler RGB mod (Famicom Titlers have a internial amplifier), because the Video-Output from the normal PPus is bad.

Only "Totally Rad" from Jaleco works with the wrong colors. Life Force doesn`t work correctly on a US-NES, but on a AV-Famicom, Final Fantasy doesn`t work correctly on a AV-Famicom, but worls fine on a US-NES (all with the same PPU).

Bye Markus


Castlevania 1-3 and Kirby works fine on my RGB NES.

I have 3 RGB NES Consoles:

-Famicom Titler AN-510, Colorbooster for the "RGB to S-Video" Chip on the Mainboard, EASY to modified :-)

-japanese AV-Famicom

All VS. Unisystem PPUs hold a different color palette into the PPU (labled as RP2C04) except VS. Tennis and VS. Duck Hunt.

Bye Markus


QuoteAll VS. Unisystem PPUs hold a different color palette into the PPU (labled as RP2C04) except VS. Tennis and VS. Duck Hunt.

Are you saying VS Tennis + VS DuckHunt have PPUs compatible with NES machines + games?


Yes :-)
You can also buy just the Chip-Sets to save shipping :)
It`s good to know to buy VS Tennis, because its a "2 Monitor" game and have 2 RGB PPU`s (!)

Bye Markus


Does VS Tennis + VS DuckHunt have a more accurate nes-palette than the playchoice ppus, or are they the same?



It`s the same PPU, labled as RP2C03B and hold the same palette and game-compatibility like the Famicom Titler PPU RC2C05-99.

I really don`t know what`s the difference from RP2C03B and RC2C05-99.

You can also install the RGB PPUs in a PAL-NES, if you change both the crystal and CPU.

You can also use the Colorbooster from N64, but the Quality isn`t the best.

Bye Markus



it's quite normal that your RGB (ntsc) picture is much brighter than the A/V-out(pal) picture...
easiest way to see that is when you hook up an pc with tv out to your tv and switch
between pal/ntsc mode...
as you will see the pal image iss darker...


Pal rgb nes is possible?

Hmm.. okey.. Moosman! Can you explain a little bit further how to do a palmod, please?

Now I have this us-rgb-nes. Do you think it is possible to make it switch between pal and ntsc, if I switch between all the necessary chips?

Like, What is the difference between a PAL-NES and a NTSC-NES?
If I use a PAL-Nes, what chips need to get replaced? And should I use chips from the NTSC-NES then?

urgh.. things get complicated :(


Guest_Great Hierophant

I believe that it is important to remember what video system a video game system was designed to use.  For the NES, while the graphics for most games were originally drawn on RGB computers, eventually they had to be tested on the real home system and customized to the various quirks of NTSC color and picture.  The optimized for NTSC because that is what the vast majority of gamers would use.  (PAL was a quite secondary market and the arcade Playchoice and VS. Systems were developed after the development of the NES.)  

NTSC is well named "Never The Same Color Twice", because the quality and settings of TV circuity varies from one set to another.  The NES PPU, the 2C02, relies on certain NTSC quirks, like overscan, colorburst, odd and even fields, to produce its picture.  Timing is crucial to proper NES video display, look at any emulator.  As RGB does not use a colorburst signal, there are some differences between the picture and games that rely heavily on NTSC timing might not work exactly.  (Any graphicalglitches would be slight.)  

If you do this mod, assuming you do it successfully, what will you gain from it?  Better color?  Color is color, and it has been notoriously difficult to find proper RGB values for the NES's NTSC color palette.  Also, once you pick the colors, and believe me that some of the RGB colors of the 2C03 or 2C05 are wrong, as the TV screens show.  I also think that some of the charm of the NES lies in its easily changeable palette.  Balanced tint and color controls will give as close to the true colors as possible.  I seriously doubt you will get square pixels because 2C0x PPUs are programmed to overscan horizontally, and unless you have a very good monitor without curvature you will lose some of the top and bottom.  And believe me when there is generally nothing you need to see above line 8 or below line 231.  (Programmers leave garbage on those lines so they can have more time for visible graphics.)  A sharper picture perhaps?  Having not looked at a good Playchoice screen recently, I cannot answer this in the negative.  Certainly, RGB should remove jagged vertical lines, as that is an NTSC quirk, and the improved circuitry would make the individual pixels crisper, bleed less, and allow single pixels their proper color (eliminating artifacing.)

For the NES, I tend to see the RGB mod as expensive without much of a benefit.  The proper PPU chip is difficult to find.  Replacing the chip can lead to a fried chip or a fried NES if something goes wrong.  NESs and Famicoms are no longer made and are expensive to replace.  Good RGB solutions are expensive for those outside Europe.  Custom cables also have to be made.  This is alot to ask for somewhat crisper picture that was never intended in the first place.  Also, as someone who replied to my quoted post above pointed out, upgrading the video standards can sometimes make graphical effects intended for lesser video standards look like crap under the unforgiving eye of RGB.  


Who cares if the system was designed for RGB or not?
The mod was performed because this magic ppu makes it possible,
and because it was a FUN project!

Yeah, there's some glitches in some games, and the colors isn't 100% correct,
but it works and looks great for most games! And the rest, well, that's too bad..
but I still have a spare A/V system for those :).

And NO, NES systems are NOT expensive.
It's the most sold console on earth. You can get one very cheap if
you know where to look. Like fleemarkets, or just a simple "want to buy ad".
And as I live in Europe, RGB related stuff like cables is common and cheap.

Total cost for this project was about 15$.


I still want a bit more detailed information about a NES-PAL-RGB mod!


[ I still want a bit more detailed information about a NES-PAL-RGB mod! ]

OK, but the NES run in 60 Hz.
It`s easy, swap both the crystal. The crystal from PAL-NES is labled with 26.601712 MHZ (red), NTSC-NES or all PC10 Arcadeboards 21,47727 MHZ (blue).

The result is a half pal & half ntsc NES, because the CPU from a pal-nes is not the same like from a ntsc nes.

Bye Markus


Ahh.. thanks!

But, what will the difference be, play-wise, when using pal/ntsc nintendo, compared to an real ntsc one?

A pal Nintendo with ntsc-picture? Can I play pal games on it with correct pal-speed?


Can someone tell me where the RP2C03B chip is located on the Playchoice  motherboard?  I just bought a Playchoice motherboard off eBay and I can't read the numbers on some of the chips.  One of the chips looks damaged...I'm afraid that is the one I need, but I'm not sure since I can't read all of the other numbers.

There is a large chip near the side labeled RP2A03E.  There is another large chip right beside it which is damaged so I can't read the number.

I am pretty new to modding...the only mods I've done were adding the AfterBurner to my Game Boy Advance and adding the TV adaptor to my Game Boy Advance.  So I'm not sure where the "critical" part of the chip is...I would imagine a lot of the material in a chip is actually protective casing.  At any rate the black layer on top where the number is printed has been broken off.  The pins are all still in good shape.  Basically, what is left of the chip looks like a white board with a black square in the middle.  I'm guessing that black square is the "critical" part of the chip.  It still looks like it is in tact.  I'm just not sure how good of a chance it has of actually working.   :(  


Ahh! Nevermind, I just stumbled across a schematic (

It looks like the chip in question is in fact the RP2C03B.  I'm guessing that in its condition there is not much chance of success... :(



Buy a VS. Duck Hunt or Vs. Tennis ROM-Kit, because shipping costs for just the Chips are cheaper instead a PCB.

Some PPUs are labled as RC2c03b instead of RP2c03b (or in a grey instead of white ceramic package) but it`s near the same Chip (you need a 120 pF condensator instead of a 68pF condensator).

I received the PPU from VS. Top Gun yesterday. The Chip is similar labled like the PPU from Famicom Titler and it hold the NES Homesystem colorpalette, but unfortunately the PPU is not NES Cartridge compatible (maybe difference input Pinouts, i dont`t know).

@Rockard: I have a new RGB Amplifier with pots :)

Bye Markus


Thanks, Moosmann, I will try getting a Vs. Duck Hunt ROM-kit.

Is condensator another name for capacitor?  If I remember my physics correctly (I'm quite rusty) pF means picofarads, which is a measure of capacitance.  Just wondering because I have never heard the term condensator.  


Moosmann: Oh, you say so? =)

Tell me how you did it! Diagram! =)

Can the values be changed without loosing ny quality?


Capacitors, as they're called in North America, are called condensers in other parts of the world (including, AFAIK, Japan and the UK).


QuoteIs condensator another name for capacitor? If I remember my physics correctly (I'm quite rusty) pF means picofarads, which is a measure of capacitance. Just wondering because I have never heard the term condensator.

Yes, pF is picofarads and sorry for my bad english, i mean capacitor.

QuoteTell me how you did it! Diagram! =)

Send me an Email.

Bye Markus


hippy dave

QuoteCapacitors, as they're called in North America, are called condensers in other parts of the world (including, AFAIK, Japan and the UK).
they're called capacitors in the uk, just so's you know ;)  


I recently fitted my modded (read: butchered) NES with the 68pF cap and it works like a dream. I encountered a bit of trouble with the amp, though. At least with a toaster-style NES, application of Waltarzar's RGB amp led to notable vertical bars acting as a sort of filter over the image, and a notable interference pattern was present. After some testing, I found that the amp was insufficeintly powered. Use of an external power source (the one I use now, at 250mA, provides plenty of current) removed both problems.

I also tried the powered amp with the modded TG16. It greatly alleviated the vertical bars problem in that situation as well, leaving a crisp and beautiful picture. Happy day!


I'm still looking at attempting the RGB mod, but there are a few design details I need to get worked out in my head before I start.  I'm still at the point of brainstorming, so there are a lot of things up in the air right now.

Has anyone attempted this mod on a top loading NES?  I haven't opened mine up yet (still need to get a 4.5mm security bit), but there's obviously less space in there than in the front loader.  I'm just not sure how much space I need yet.

What kind of output connector do you guys use?  I've seen a few ideas out there, but I can't decide which one I should go with.  I guess part of it depends on whether I use the front loader or top loader.  

I have seen the idea of replacing RCA connectors with 3.5mm stereo headphone jacks, to get 2 signals from one plug.  Using the front loading system, it seems like that could work without having to carve up the system.  By replacing the 2 RCA jacks on the side with stereo headphone jacks, they could output a total of 4 signals (red, green, blue, sync).  Then the RF modulator could be removed and audio could be output from the back via RCA connection.

Then there's also the idea I've seen on this site of using the D-sub 9 connector, which is cool because you can output everything from one plug.  But that means creating a new hole in the console's shell.  Thinking back to my AfterBurner install on the GBA, carving plastic with an exact-o knife isn't exactly put it lightly.  I'm not sure if there is a better cutting method though.  It seems like using a power tool of some sort would be likely to shatter the plastic, but then again I haven't tried it.  Of course considering how much top loaders go for on eBay I don't think I want to try that just to see what happens.  ;-)

Of course I guess another factor to consider is the input connector on the RGB to component transcoder.  The ones I've managed to find either take SCART input or HD15.  I have found an adaptor that converts D-sub 9 to HD15, but I'm not sure which pins map to which.

Another thing I've determined after looking for RGB->component transcoders is that they are quite pricey.  So ideally if multiple systems are going to be modded (I'm probably getting ahead of myself here) they should all share the same transcoder via a switch of some sort.  I already have switches composite + s-video inputs, but using those would require making a custom adaptor of some sort.  If I go with a HD15 output connector I could probably use a KVM switch if I get a transcoder with VGA input.

The pinout I'm looking at for the RP2C03B only shows one sync, which would mean I need a transcoder that takes RGBS input, right?  I've seen some that only take RGBHV input, so I'm guessing those won't work.  I have found one with a multi-standard input:
It's pretty expensive though...seems like there would be something cheaper, but I haven't found anything yet.



Vertikal stripes lines ?
Yes, I have this problem with a 2sc1815 or the Waltarzar`s RGB Amp, but please let me know the difference with my Amp on your TV or Monitor.

Bye Markus

Russell Thompson

Regarding the questions about the wierd colors on the RC2C03B (RGB PPU), I've checked this chip out to try to reproduce the colors on a computer and this is what I found: this chip generates the colors VERY differently from the composite PPUs.  It has 8 different brightenesses for the red channel, the green channel, and the blue channel, which would ideally make it capable of generating 512 colors.  But you are limited to only 64 preset colors, of course, and they did not do a very good job of selecting the values for these colors.  
    The "brown" shades (07 & 08, I believe) are brighter, color 02 is WAY too bright, color 3C is too dark, and color 3B was accidentally set to the same value as color 2B.  Also, color 0B is the same as color 1A, making some dark green backgrounds look too bright.  This problem is most noticable on Mega Man 5, in Napalm Man's level.  When using a composite PPU, the background will resemble a dark jungle with palm trees and grass swaying in the wind in the foreground.  But on the RC2C03B, the jungle is bright and you cannot even see the grass at all (and the palm leaves can only be distinguished by the black outlines).  
    There are other differences too.  Colors 0C, 1C, 2C, and 3C are all black on the RC2C03B.  Also the color emphasis bits work differently - they simply force their corresponding channel to full brightness, so if you turn on all 3 emphasis bits, the screen will be solid white.
    By the way, if anyone has ever had any problems with scrambled backgrounds on some games when using the RC2C03B in an NES, try putting a 1K resistor across pins 10 & 11 of the 74LS373 IC.  This should fix that problem.  Other resistor values may work, but I believe this one is the most effective on all games.


If the French NES already outputs RGB can't it just be used as-is, at least for those of us who mainly have PAL games?


The french NES doesn't actually output real RGB, it just uses a FBAS to RGB encoder. It's just nice to use because of the multi-AV socket and the Nintendo Scart cable which comes with it.

The picture produced by the french NES without adding a REAL RGB chip is a bit more colorful than the standard video signal, but hardly any sharper.



In case anyone really cares about the info. I provided on the RC2C03B chip, I made a few mistakes.  I said color 02 was too bright - I meant color 03.  And it's 0D, 1D, 2D, and 3D that are all black, not 0C, 1C, 2C, and 3C.  It's hard naming the colors off the top of my head.  Hope I didn't confuse anyone.


Nice info Russel, I think to get accurate RGB from a NES the only hope is that someone remake a PPU using a FPGA.

Don't think that something we gonna see anytime soon unfortunaly :(.


QuoteBy the way, if anyone has ever had any problems with scrambled backgrounds on some games when using the RC2C03B in an NES, try putting a 1K resistor across pins 10 & 11 of the 74LS373 IC.

I just solder an 1 K-Ohm resistor between pin 10 & 11 of the 74LS373, but I do not see a difference in the MM5 Napalm Man Stage after to solder the resistor.

Which games I can see the difference with and without the 1K resistor ?

Bye Markus


No, sorry if I confused you - the 1K resistor won't fix the colors - that's for games that have problems with the graphics.  When I installed the RGB PPU in my top-loading NES in hopes of eliminating the vertical bars (which I finally figured out how to eliminate recently), I had a problem with almost any game that was not released in a Playchoice format, where the backgrounds would appear to have "static", or other tile errors.  The signal going to pin 11 of the 74LS373 goes through several buffers on the Playchoice boards, with jumpers to select how many buffers to use.  Having no luck getting this to work on the NES, I noticed that touching the line made some minor improvement, and when trying different resistors tied to the ground or +5V, I found that a 1K resistor to the ground eliminated all of the problem (a little bit still shows in Bubble Man's level on Mega Man 2, but it's not very noticable or distracting).
    There's really no way to fix the color problem, except to come up with a new PPU.  Or, if you can come up with some sort of ROM or programmable logic chip to take the palette data from the CPU and transmit a different palette number to the PPU.....this won't do any good on the RC2C03B (and probably not the RC2C05-99 either), but the RP2C04 PPUs, in addition to having the colors moved all around, have additional colors, including a dark red, dark green, dark blue, 4 more shades of gray (making a total of 8) and shades of brown.  I recreated the palettes for most of these PPUs on my PC and tried making a new palette by moving the colors around, and came up with a nice palette that is a lot closer to the NTSC/PAL palette than Nintendo's RGB palette.
    Now if only I can put something in there to alter which color is used, as I mentioned.....I don't know if I can come up with it, but I'm trying to find a way, which will also help me with another project I'm working on: a vs. ROM to Famicom adaptor.
    I'm wondering too, if I can do this, if it's possible to get a hold of those overstock RP2C02 chips that a lot of these wholesalers have, and run 3 of them in a NES - all 3 only showing shades of gray, but using one for a Y signal, one for an R (or R-Y) signal, and one for a B (or B-Y) signal.  Hmmm.....kind of far-fetched I guess, but it may be possible.


Wow amazing project Russel, hope you succed,

Also, would be nice that your VS system adapter use the famicom expansion port for lan play with another famicom using another vs system adapter.

But you might have some problem to sync the two system, since they don't power on at the same time.

Would be awsome to play Tennis at 4 players on two screen using two famicom!!!

If IIRC the link between the two cpu is done by one of the Out line (Out0/Out/1Out2)