Nintendo 64 RGB Modification
Small overview of the video signal
The Nintendo 64 belongs to that great generation of consoles which did not provide high definition image like modern videogames consoles. The video signal produced was designed for normal color TVs that are equipped with a common video input, such as the composite or through a SCART connector.
The composite signal
When buying a Nintendo 64, Nintendo supplied with the console a normal video cable consisting of three plugs; the yellow one, the white one and the red one. The yellow plug is for the video signal, while the other two are dedicated to the sound. This way of transmitting the signal is called composite video.
The yellow cable contains the video information to be sent to the TV. The image is decomposed into three sub-channels: brightness and colour, accompanied by a channel for synchrony control. Sending all this information with a single cable offers the only advantage of not having any more connectors to clean (yes, I also clean the cables, not always but it happens :D). The video quality is very low.
The physical characteristics of the cable allow it to carry only a certain limited amount of information to describe the image. This amount is indicated by the term bandwidth. Without going into the technical details, the bandwidth made available by this system is quite scarce considering the number of different signals one has to deal with.
For this reason, during the standard definition, it was decided to transmit less information about the brightness to allow the color to be visibly acceptable. This compromise leads to a lowering of the general image quality, and in the most tragic cases there are video disturbances caused by incorrect alignment of the color channel with the brightness channel.
The RGB signal
With the RGB signal things go much better. You have three independent available channel, practically three wires, to send the information. Also with RGB the image is decomposed: the red component of the image will be transported in the first channel, the green component in the second and finally the third component in the blue channel.
The control and synchrony signals are sent by additional/separate channels. These channels are usually present in the SCART cable.
The RGB allows you to transmit the image in the best possible way without compromises. The signal will go directly into the cathode ray tube of the television to stimulate the pixels of the screen in an appropriate way.
Why choose RGB signal
With an RGB signal the colors are more "live" and have better, sharper edges. This contributes to a better gaming experience.
Unfortunately, as far as I know, Nintendo only provided RGB in the early NTSC consoles, while PAL consoles have been manufactured with only composite signal, but there's a solution to that too!
Solutions for obtaining the RGB signal
As mentioned earlier, the first NTSC consoles provide the RGB signal which, luckily for us, we can exploit by making some small soldering on the motherboard.
Keep in mind the pinout of the connector on the motherboard, we will need it to locate the PINs of interest to us.
| PIN | First name | Description |
| 1 | R | Red (Useful for editing) |
| 2 | g | Green (Useful for editing) |
| 3 | csync extension | Composite Sync |
| 4 | b | Blue (Useful for editing) |
| 5 | GND | Mass |
| 6 | GND | Mass |
| 7 | Y | S-Video Y (brightness) |
| 8 | c | S-Video C (contrast) |
| 9 | CVBS extension | composite video |
| 10 | +5 | +5V VCD power supply |
| 11 | L+R | Left + Right Audio (Mono) |
| 12 | LR | Used to calculate stereo |
Signal from VDC-NUS chip
The chip that generates the signal, the one that converts digital information into analogical information, is the VDC-NUS. It takes care of loading the data coming from the memory and transforming i into a signal that our TV is able to display.
First method: take the signal from the resistors
All you have to do is connect three wires to three points under the Nintendo 64 motherboard, and connect the other end of the wires to the video output connector (refer to the table above). That's all, by doing so you will enable the RGB output.
The points where to solder the wires are located under the motherboard, refer to the photo to locate the affected area. The signals must be taken from the resistances R8, R9, R10. If you want to enjoy a color boost short the C143 with R10, but the signal may flicker.
Second method: Solder the wires directly to the chip
This system is the one that commonly circulates on the internet, it involves performing a job similar to the previous modification, with the only difference that the signals must be taken directly from the chip.
I advise you against doing this: you will get a darker image. Not all televisions are able to compensate this additional darkness by adjusting the colour/contrast levels.
Anyway, if you like to do it, locate the chip on the motherboard, and solder it using the following diagram.
Last chance, for the man who never has to ask!
This last method involves the complete replacement of the VDC-NUS chip. You will need to obtain special CPLD chips, and you will need the technical skills to program them.
After obtaining the programmed chip you will have to assemble an A/D conversion circuit to be soldered together with the chip.
Once this is done you will have to take care of soldering all the video bus signals to this new circuit and finally connect it to the video output.
Concluding
We can close now with this article. If you are lucky enough to have an NTSC console with RGB output available, use the first method, it works for most televisions. The last solution is interesting because the technical data of the project could be used to convert the digital signal in various ways. For example with the proper technical skills, time and money, I think it is possible to bring the Nintendo 64 into an HDTV.
