NES RGB mod

[Bostich]

I've been working on doing the RGB NES mod on and off for quite a while now.  Anyways, I finally got to the point where I try to hook it up to my TV.  So I get everything plugged in and turned on, but all I get a nice black screen.  Sometimes after I leave it on for a little bit the screen will turn gray and start flickering.  I turn it off after that happens because I don't know what's going on.

What I'm trying to figure out now is how to diagnose the problem.

First, some info about what I've done so far for the mod:

1. Desoldered the original PPU from the NES
2. Soldered a 40-pin IC socket where the PPU used to be
3. Soldered wires to pins 14,15,16,and 21 (red, green, blue, and sync, respectively)
4. Took the RP2C03B chip off a Playchoice PCB and plugged it into the IC socket on the NES board
5. Connected the four wires (RGBS) to two stereo headphone jacks.  The wires are just twisted on for now, but these will be soldered if I can actually get this mod working.
6. Each stereo headphone jack has a 3.5mm stereo to 2x RCA adapter plugged into it.
7. Each adapter has an RCA stereo audio cable connecting it to a RGB+composite to SCART adapter.  Sync is connected to the composite video input.
8. The SCART adapter is plugged into my RGB to component transcoder.  (Keene RGB2C, which I have tested on other systems and it works)
9. The output of the transcoder goes through a SCART to 3x RCA (component) adapter then into my TV.

Now, here is what I've tried so far to troubleshoot:

1. Verified the NES power light is not flashing, so it should have a good connection to the cart.
2. Checked the connections of my 4 wires. I actually tested these connections at the ends of the RCA cables where they plug into the SCART adapter. The way I tested these connections was by setting my multimeter to measure resistance.  I touched one probe to the tip of the RCA cable and the other probe to the NES motherboard.  All four showed a very low resistance--sync was about 5 Ohms; red, green, and blue were about 0.7 Ohms.
3. Checked the connections on the PPU chip to the board using the same technique.  I touched one probe to the pin on the chip itself (not the socket) and touched the other probe to the motherboard.

Is there a way I can test the PPU chip itself to see if it might be dead?  I'm running out of ideas for things to try.  Thanks in advance.

[Moosmann]

1. Desoldered the original PPU from the NES
2. Soldered a 40-pin IC socket where the PPU used to be

You need a praecision instead a standard IC socket for a good connection.

3. Soldered wires to pins 14,15,16,and 21 (red, green, blue, and sync, respectively)

The RGB Pins should not connect from the socket to the pcb, because it is ground.
You have also ONLY lift the 3 RGB pins, not Pin 21.
Take composite sync from the yellow Video RC Socket from the HF-Modulator.
You need an amplifier for the RGB signal.

5. Connected the four wires (RGBS) to two stereo headphone jacks. The wires are just twisted on for now, but these will be soldered if I can actually get this mod working.
6. Each stereo headphone jack has a 3.5mm stereo to 2x RCA adapter plugged into it.

You need a ground connection. You also need the 68pf or 120pf capacitor for the OE/WR line.

Is there a way I can test the PPU chip itself to see if it might be dead? I'm running out of ideas for things to try. Thanks in advance.

Don`t connect the NES to the transcoder and check, if you get audio (music from the game) from the red Audio Chinch socket. If you get music, it is a signal problem, if you don`t get music, mostly the PPU is broken or a wrong PPU inmstallation (Lift RGB Pins from ground).

Post or send me photos please.

Bye Markus

[Bostich]

Thanks for the reply, Moosmann!

You need a praecision instead a standard IC socket for a good connection.

Here's the one I bought:  http://www.cascadesurplus.com/catalog/prod...47e08156fff9910

Should this one work?  I'm not actually sure what to look for, aside from the number of pins and the pin spacing.

The RGB Pins should not connect from the socket to the pcb, because it is ground.
You have also ONLY lift the 3 RGB pins, not Pin 21.

Please bear with me as I'm not quite familiar with the terminology.  When you say "lift" a pin, do you mean to bend it in such a way that it does not make contact with the PCB?

You need an amplifier for the RGB signal.

I was kind of thinking that after reading through a couple of threads regarding the NES RGB mod.  Should I be able to see anything without the amplifier?  If I can at least get something without the amp, even a dim picture, I will at least know I'm on the right track.

You need a ground connection. You also need the 68pf or 120pf capacitor for the OE/WR line.

I was wondering about the ground connection.  Where should ground be connected to?  I had tried connecting it to the RF shield, but I have no idea if that is a good place.  Also, I'm not sure what OE or WR stands for.   Can you provide a bit more clarification?

Here are a couple of pictures, although I realize I will have a change a few things.  For starters I soldered the wires to the back side of the board (less to work around).  However, I wasn't thinking about the cartridge tray.  It won't fit back on!  Anyways, after reading what you mentioned about lifting the pins (if I'm interpretting that correctly), there's no way it could work the way I have it wired.  My digital camera doesn't have optical zoom so I tried to get as close as possible without making it too blurry.  It actually takes decent pics at a distance...I guess this is the first time I really tried to take a picture of something this close up.

The back side of the board, with the 4 wires (I realize this will probably have to change):

[picture deleted]


The front side of the board, with the PlayChoice PPU sitting in the socket:

[picture deleted]

EDIT:  pictures deleted since they are incorrect.

[Moosmann]

Here's the one I bought: http://www.cascadesurplus.com/catalog/prod...47e08156fff9910

It is a standard lowcost version. It`s not the best, but should work.

QUOTE (Moosmann @ Aug 29 2005, 10:42 AM)
The RGB Pins should not connect from the socket to the pcb, because it is ground.
You have also ONLY lift the 3 RGB pins, not Pin 21.
Please bear with me as I'm not quite familiar with the terminology. When you say "lift" a pin, do you mean to bend it in such a way that it does not make contact with the PCB?

Yes, because Pin 14-17 is connect to GND. If you solder all Pins to the PCB, the 3 RGB Pins make contact with the pcb (Ground).

You can take GND from every place from the PCB.
I send photos comming next 2 days.

Bye Markus

[Fix_Metal]

wait wait wait....
a RGB mod for NES? Nintendo Entertainment System 86?
o_O

[Endymion]

You're late to the party.

The PlayChoice 10, essentially the NES/Famicom hardware, outputs RGB. The concept here is to remove the components for RGB from the PlayChoice 10 and add them to an NES to provide RGB.

[Fix_Metal]

lol
ok thx

[Bostich]

Moosmann, were you planning on posting those pictures in this thread or were you going to email them to me?  I just noticed the email address in my profile was out of date so I updated it.

[Moosmann]

Oh...I forgot

RGB Amplifier:


RGB Lift from ground:


Sync and Audio:


Final (black wire is 5V, brown wire is ground):


...and if you have some graphic glitches, use 120 pF:


Bye Markus

[Bostich]

Awesome!  Thanks for posting those pictures, Moosmann.  I'll resume work on the mod this weekend.

I just have one more question (for now):  what is that black material you have in the "RGB Lift from ground" picture?  I assume it is just some type of non-conductive material?

[Guest_Moosmann]

Yes, it is. Cut the 3 Pins from the socket and solder the rgb wires directly.

Bye Markus

[acem77]

Moosmann do you have any screen shots you could post?
would you ever do this mod for money? if so how much
i would love to have an rgb nes!

[Moosmann]

Moosmann do you have any screen shots you could post?

would you ever do this mod for money? if so how much
i would love to have an rgb nes!

Send me a PM please.

Bye Markus

[acem77]

i think i will try this rgb mod on a ntsc model 1 nes.

there are few things i was hopping to find out.

were is the best place to get the playchoice 10 ppu? checked ebay a few times only can find the games.

with out the rgb amp will there be a stable image. i want to worry about the amp after the rgb is all functional.

also i wanted to know if the same rgb amp for the turbo duo/pc-engine and or the n64 would work.

i have made both. the n64 amp is mush easier to make than the pc-engine amp.
the n64 amp even works great on my turbo duo. wish i would have know this earlier.
i just did the rgb mod to my n64 and fig i would make a few amps cuz it was so simple. then i tested it in my duo and it worked

why was the composite video used as sync instead of pin 21 from the ppu?
thats what it looks like in the picture.

i have had no luck with using composite video as sync. my xrgb2 plus always creates a pixel crawl effect even if i use the lm1881 chip.
check my blocky rgb artifact post on this forum to see what i was getting just from composite noise.

has any one here tried the stereo mod for the nes?
is it even worth the effort?

thanks in advance

[Moosmann]

were is the best place to get the playchoice 10 ppu? checked ebay a few times only can find the games.

Search the VS. Games Kit Duckhunt or Tennis.

also i wanted to know if the same rgb amp for the turbo duo/pc-engine and or the n64 would work.

N64/PCE Amps works, but the picture quality is a little to dark. Take my amplifier.

why was the composite video used as sync instead of pin 21 from the ppu?
thats what it looks like in the picture.

Pin 21 from the regular RP2C02/RP2C07 PPU output PAL/NTSC composite video, RP2C03/4/5 PPUs output composite sync. But this signal is unamplified, so that you take the amplified signal from the point in the picture.

Stereo Mod works great.

Bye Markus

[acem77]

Pin 21 from the regular RP2C02/RP2C07 PPU output PAL/NTSC composite video, RP2C03/4/5 PPUs output composite sync. But this signal is unamplified, so that you take the amplified signal from the point in the picture.

ok so if i understand correctly the RP2C03/4/5 PPUs are from the playchoice 10 pcb. and when installed in the nes pin 21 is amplifiyed by an amp in the nes that would normaly amplify the composite video?

[Guest]

Yes

However, Playchoice 10 PPUs are only RP2C03B.
Vs. PPUs are difference each game.

Bye Markus

[acem77]

However, Playchoice 10 PPUs are only RP2C03B.
Vs. PPUs are difference each game.

will any of these ppus work good?
or is one better than the others?

[Guest_Moosmann]

Only the PPUs from Vs. Duck Hunt / Tennis works (...the 2C03).

The 2C04 PPUs do not works.

http://www.crazykong.com/pins/NintendoVsChips.pin.txt

Bye Markus

[Guest]

Hello, I live in Tokyo, and I was wondering if it was possible to convert my Famicom to RGB as at the moment the picture is awful.  Thanks.

[Moosmann]

You can modified your AV Famicom here:
http://homepage3.nifty.com/F-LABO/?07290000

Bye Markus

[acem77]

However, Playchoice 10 PPUs are only RP2C03B.
Vs. PPUs are difference each game.

Only the PPUs from Vs. Duck Hunt / Tennis works (...the 2C03).

The 2C04 PPUs do not works.

if i under stand i can only use the vs tennis or duck hunt and that
uses a RP2C03 ppu ?

the stand alone play choice 10 duck hunt and tennis will not work and they use a RP2C03B ppu?

if any one is willing to sell a vs tennis or duck hunt pm thanks.
ebay has come up with nothing so far.

[Guest_Moosmann]

Some words

-Playchoice PCBs is a Hardware witch all parts and ONE PPU (works witch NES RGB Mod), the games is ~like a nes cartridge and do not have a PPU.

-VS. Unisystem PCBs are "nacked" witch not all parts (I mean, witchout a PPU). The games comes witch the ROM-Chips and every game comes witch a PPU. If you buy a VS. Duckhunt Rom-Kit, you get some ROM-Chips and the RP2C03 PPU (works witch NES RGB Mod). However, you also can get a VS. PCB witch a installed game.

It doesn`t matter, how labled is the PPU or if its in grey or white ceramic package. Only Rx2C03x is the right part, RP2C04-000x do not work.

x=difference

Bye Markus

[acem77]

Playchoice PCBs is a Hardware witch all parts and ONE PPU (works witch NES RGB Mod), the games is ~like a nes cartridge and do not have a PPU

ok i can buy the playchoice pcb and use its ppu?
so the playchoice 10 ppu will work just as good as the vs rom kit of duck hunt or tennis?

thanks again.

[leonk]

Moosmann:

Have you noticed any problems from using this PPU when compared to the original?  According to Kevin Horton, the playchoice PPU has a different color template than the home system, resulting in some colors looking different and other games not working at all.

A good test would be to run Kid Icarus on the system and compare the colors (especially the brown of the walls) and see the difference.

Looking forward to your reply.

[Computolio]

   Has anyone put a NES PPU on a Playchoice-10 board? It seems a shame to plunder a working board just for one chip, even if it is a Playchoice-10.

[DarthCloud]

Has anyone put a NES PPU on a Playchoice-10 board? It seems a shame to plunder a working board just for one chip, even if it is a Playchoice-10.

Yes I did it, but the output is only black&white because an normal NES use an variable cap on the clk line of the PPU for adjusting the color. Since this cap is not present, the output is B&W. But if you rebuilt the nes clk line on your PC10 it sould work fine.

[Rockard]

Rockard:

Have you noticed any problems from using this PPU when compared to the original?  According to Kevin Horton, the playchoice PPU has a different color template than the home system, resulting in some colors looking different and other games not working at all.

A good test would be to run Kid Icarus on the system and compare the colors (especially the brown of the walls) and see the difference.

Looking forward to your reply.

Well thank you! I'm happy to answer!

I think there is n���thing you can do about it! I tried myself screwing around with pots to adjust the colorvalue on each rgb-line to match the nes, but it was just foolish, since grey won't be gray when adjusting one color.

By using Marcus Brandells guide, there is only about 1 or 2 games that have real problems with the ppu. (that I am aware of, anyway)

Hack on! I think it is totally worth it. The colors are an insy bit off, but you'll get used to it. Certain combination of colors looks ugly, like brown and red, but for the most time it is just a bliss to look at the sharp, glorius screen.

[Moosmann]

Have you noticed any problems from using this PPU when compared to the original? According to Kevin Horton, the playchoice PPU has a different color template than the home system, resulting in some colors looking different and other games not working at all.

A good test would be to run Kid Icarus on the system and compare the colors (especially the brown of the walls) and see the difference.

Looking forward to your reply.

Yes and no.
I mean, the color brown from Kid Icarus is a little brighter with the PC10 PPU, but if you take a look on the Boxartwork from this game, the color brown (hair from Kid Icarus) is the same like the brown from the PC10 PPU.

I think, red and brown is difference between the NES and PC10 PPU because you get quality lost with the NES PPU (Video or Antenna) instead RGB.

99% the games take the right palette because Nintendo also use this PC10 PPU to make screenshots for the Nintendo Magazin or boxartworks.

From many games, only Totally Rad from Jaleco have wrong colors (background from the first Stage black instead white) but this game is unlicensed in Japan. The boxartwork screenshot from the japanese version have also a black background

If you have a USA NES and solder the 68-120 pF capacitor, all games run glitchfree.

Bye Markus

[Guest_Great Hierophant]

Any game that uses the color emphasis bits of the 2C02 NTSC PPU will have problems with a system that uses a 2C03 RGB PPU.  These include Konami's Noah's Ark (unplayable), The Immortal (unplayable), Just Breed (unplayable), Super Spy Hunter (glitch), Airwolf (unplayable) The Fantastic Adventures of Dizzy (glitch).  Any use of the color emphasis bits will turn graphics completely white for those graphics which use them on a 2C03 RGB PPU.  

Also, the 2C03 has a somewhat different palette colors, and three entries which appear as gray on an NTSC PPU will appear as black on a RGB PPU.  This accounts for the loss of detail in several games.  

[Moosmann]

Thanks for this info.
I know, "The Immortal" don`t work.
The PPU from "Sharp Famicom Titler" use the same color palette and it is a licensed Famicom.

Bye Markus

[Guest]

finally got the playchoice 10 ppu for my nes rgb mod!
i used the simple n64 rgb amp to boost the brightness as you can see it works great.
it looks great. i also did the stereo mod and love the new stereo sound.
here are some pics of the nes with out rgb then with rgb hooked up to my samsung dlp through a xrgb2 plus.

thanks a lot Moosmann your help made this mod very fast and simple to do.

composite  


rgb  B)



now i have to work on a rgb mod for my final rgbless system the 3do......

[acem77]

the post above was from me ..Grrrrr i hate when i post and did not sign in...

[Moosmann]

Do you see vertikal stripes lines from Castlevania 2 -Simons Quest (title screen only) ?

Bye Markus

[acem77]

i do not have that game to test.

[Bostich]

Holy crap, this is awesome!  I still have a lot left to do on the mod, but I'm actually getting a picture now.  I haven't built the RGB amp yet, so the picture is really dark...I just played around with my TV's settings a bit just to test it out.  I also need to install the capacitor to pin 24 (haven't been able to find the right cap locally so I'll have to order online...just haven't gotten around to it yet).

At any rate, I just played through a couple of levels of SMB2.  Despite the picture being dark with wavy lines, I can still tell it is going to look a lot better than composite once it's all done.    

[acem77]

lucky me i did not need the cap.

[Bostich]

OK, so I finally got the RGB amp put together.  (Yeah, I guess that makes me kind of slow, but I blame Dragon Warrior 7 )  Anyways, the picture is definitely brighter now, although I am seeing a strange effect.  It looks like everything is smeared horizontally.  This makes the picture look blurry, although the horizontal edges of things are still sharp.  (i.e., no blurring/smearing vertically)

I have tried connecting each of the red, green, and blue signals individually and noticed the effect is present on all of them.  This makes me think it isn't a case of me making a bad connection by accident.

I was following Moosmann's schematic when building the amp, although I made a few deviations:

1. I used transistors NTE 123AP and NTE 159.  According to the cross reference I was using, I think they should be equivalent to BC 33725 and BC 557, respectively.  NTE Cross Reference

2. My resistors are 2% tolerance.  I was having a hard enough time tracking down all the right values in 2%, let alone 1%, so I went with 2%.  I didn't think this should make too much of a difference.

3. I used non-polarized capacitors.  I wasn't sure how to tell + from - on a regular capacitor, so I thought it would be safer to get a non-polarized.  I had read somewhere that a non-polarized capacitor could always be used in place of a polarized capacitor, so I didn't think this would be an issue.


I went ahead and took a picture, although it didn't really capture the effect very well.  First of all, I don't see those vertical lines on my TV so I'm not sure why they showed up in the picture.  Secondly, the smearing effect is a lot worse looking at the TV than what the picture shows.  You can still see it a little in the picture though.  Anything with black on the right edge has a noticeable smearing effect in the picture (it looks worse on the TV).

Yoshi Title Screen

Has anyone ever encountered this sort of problem when building an RGB amp?  Any help would be greatly appreciated.

[Moosmann]

You need an 10 uF Electrolyt Capacitor (also works uop to 220uF) with polarity, and you get a nice quality

The short Pin is -, the long pin is +

Bye Markus

[Bostich]

I went and picked up a 10 uF Electrolytic capacitor with polarity today.  I removed one of the non-polarized capacitors I had used and replaced it with the polarized capacitor.  I only did this to one amp just to test it out.  Red happened to be the most convenient.  I am still seeing the same smearing effect, even with the polarized capacitor.

After a little digging around it sounds like the slew rate of the amplifier isn't fast enough.  I don't know enough about amps to know how to speed it up or even which component(s) would be responsible.

Would the transistors be responsible for something like this?  Perhaps that cross reference I was using was wrong.  I think the only reason I used those NTE transistors is that I was having trouble finding the BC33725/BC557...or maybe the place I wanted to buy from just didn't have them.  (I originally wanted to try and order all the components from the same place to save on shipping, but that proved to be a futile effort.)