Clean RGB Install (SNES)
The SNES already outputs RGB out of the AV port, however it has a DC offset which makes it incorrect voltage levels to most monitors.
Most people solve this with making custom RGB cables with AC coupling capacitors and resistors. This is ok, but it's far from perfect. It introduces all problems that AC capacitors add (field droop, tilt, common mode noise coupling from the receiver side and more.
All the RGB mods I personally make are called the CleanRGB. It aims at correctly fixing the console itself to output IRE correct voltage level and signals, and the cable is then a pure DC cable with direct connections, no hidden capacitors, sync strippers, resistor or other magic.
The benefits of this are pure, perfect RGB signals not affected by your cable, receiver, or noise.
This install will involve:
- Getting RGB and Sync inputs from S-RGB or PPU2 to CleanRGB
- Severing traces from stock RGB and Sync outputs to AV Port
- Wiring RGB and Sync outputs from CleanRGB back to AV Port
- Tuning the CleanRGB for perfect IRE levels
Start by installing a CleanRGB Universal board into the SNES. Tap the RGB and Sync inputs directly from the S-RGB (BA6596) chip or PPU2.
TODO: Photo of PPU2 RGBs pins (pins 95, 96, 97 and 100).
The CleanRGB works on every version of SNES, including the Jr models. Every SNES has the S-RGB chip or PPU2 chip.
The R, G and B In go to the CleanRGB inputs, and we tap 5V from any 5V point such as the AV port or regulator, and ground from the nearby ground.
Here the RGB and Sync Inputs are coming from the S-RGB on the other side of the board and passed through an open unused capacitor hole.
The RGB and Sync outputs are connecting to the AV Port.
On this model (SNES Jr) shown, there are no connections to the AV Port for RGB so nothing needs to be cut or severed.
Next, we need to disconnect the AV port from the existing connection to any RGB pins.
The simplest way is to expose the traces running from the AV port pins and cut them. Each revision board is different layout so gently scrape away the solder resistor to reveal the copper traces coming off the AV port pins and cut the R, G, B and Sync pins.
Now wire up the RGB and Sync outputs to the AV port pins.
Checkout the setup guide for tuning the CleanRGB, or for quickness set your dials to the following positions and then tune by eye.
Using our CleanRGB SCART cable, here are the results on a SNES.
TODO
