NTSC Nintendo 64 RGB Scart Lead Booster
Although this is still valid and works, I would recommend using this guide instead to get an amplified RGB signal from the NTSC Nintendo 64.
Getting an RGB signal from a Nintendo 64 is not always easy. Once you’ve found a compatible NTSC N64, performed the RGB mod on it, you may be disappointed that the picture is too dark.
Credit for this mod must go to Mr. B. and Waltarzar for the original diagram, and whoever is hosting it over here (just in case that site ever disappears, here’s a copy). So there you have a complete list of necessary components, once you’ve got a Gamecube RGB lead (3rd party may be better, as the official one already has a tiny circuit board built into it) your only worry is fitting all of that into a Scart plug. mmmonkey designed the following layout for a little circuit board, and will attempt to talk you through making the circuit and lead!
mmmonkey bought a PAL Gamecube RGB lead from Play-Asia.com, it’s good for this mod, the 3 wires carrying the RGB signal are actually Red, Green and Blue – not that important, but it does make it a bit easier. Plus, it already has 3 100uF 10v Capacitors, they are smaller than any that I have bought separately, or seen in other Scart leads. So take the Scart lead apart that you intend to use, and check which capacitors it’s already got, and remove them ready for re-use, or throwing away. If the Capacitors have a small piece of rubber tubing over the leg/s, then keep it for use later on. Also make a note of which colour wire was attached to each capacitor/pin, pin 15 is the Red signal, 11 is Green and 7 is Blue.
In addition to the components listed on the original guide, you’ll need a small piece of Strip board/Vero board. Cut the board so it is 9 holes wide and 4 tracks high, trim the board so that it is as small as possible. You’ll need to cut through 3 of the rows, normally when you cut this board, you cut through the holes, but for this circuit, we want the board to be as small as possible, so we’re going to cut between the 3rd and 4th set of holes, and the 6th and 7th set of holes.
The copper strips are the underside of the Vero board, components are pushed through from the other side, then soldered onto the copper tracks. The first components to solder on are the 1K5 Ohm resistors, bend the resistors into the following shape.
The first resistor needs to be parallel with the board, push it through the following holes, but bend it flat as shown, then solder it to the copper side of the board
Push the second resistor through the following holes, and solder it into place, repeat for the third resistor.
You could insulate the resistors, if you have some heat shrink tubing, cover the resistors, cut to length, and heat as needed (or struggle with electrical insulation tape if you don’t have tubing), also notice how the legs of the resistors have been trimmed, you should do this for everything you solder to the board.
Next up is to cut some pieces of wire, to help you, you could use Red, Green and Blue wire. Push each wire through the following holes and solder into place (refer to the diagram above if you’re unsure of the correct holes). Make sure each wire is too long (about 5cm is more than enough), they will be trimmed to the correct length later.
Bend the transistors so they look like the following, it’s easiest to bend the outer legs first, then straighten the middle leg. Be very careful not to bend them too many times as they will snap.
The transistors are fitted as shown below, make sure you get them the correct way round (study the diagram above, where the flat side is facing, it is away from the resistors)
Now we need to fit the 100uF 10v Capacitors, the first and second are soldered in very easily, the third needs to be laid down flat again (like the resistor), study the photo’s below and the diagram from the previous page to see how this should be done. Make sure you leave a bit of a gap between the bottom of the capacitor and the Vero board, this will make soldering some wires much easier later on. Notice that the capacitors are polarised, the negative leg is usually marked somehow, see the line showing this, the negative leg is soldered so it is nearest the edge of the board.
Another wire to solder, cut a new piece of wire, and solder it as shown on the diagram – this is the 5v wire. Again, keep the wire too long so it can be trimmed to the correct length later.
Now the circuit has been finished, I usually run a knife along in-between the rows of copper, and along the cuts. This will remove any stray bits of solder that might be bridging the gaps.
Before proceeding, double check that your circuit board fits in the Scart plug casing, along with the actual Scart plug, if it doesn’t, see what’s stopping it and adjust as necessary.
This Scart cable already includes a resistor between pins 8 and 16, I removed it, but then noticed it was of the correct value anyway!
Before continuing with soldering the rest of the wires, prepare the 2 75 Ohm resistors, bend the resistors so that one fits exactly between pins 8 and 16, the other between 18 and 20. If you’ve got heat shrink tubing, or kept the stuff that was on the original capacitors/resistors, then cover the resistors as shown (otherwise struggle with electrical insulation tape).
Solder one resistor from Scart pin 8 to pin 16, the second from pin 18 to pin 20.
We’re nearly finished. If you’re lucky, you wrote down which wires were connected to pins 15 (red signal), 11 (green signal) and 7 (blue signal), use the diagram on the first page and the following picture to see where to solder the RGB wires from the Scart lead to the circuit board (the go next to the negative leg of the capacitors).
Finally, it’s time to trim the wires from the circuit board to length (3 or 4 cm should do), and solder them to the Scart pins. Start with the 5v wire, solder this to pin 8, in this guide it’s the yellow wire.
Now solder the Red, Green and Blue wires to pins 15, 11 and 7 respectively.
Squeeze it all into the Scart plug…
Re-assemble and test/enjoy.
I noticed that this Scart lead never switched the TV to AV1 automatically, this is because the Scart lead was wired up incorrectly to start with! Look closely at the following photo, you can see an orange wire going to pin 16 (the right hand side of the resistor), this wire should be going to pin 8 (the left hand side of the resistor)
Pin 8 is used to switch your TV onto the correct AV channel when you switch your console on, pin 16 is used to switch your TV into RGB mode. With the scart lead wired up incorrectly as above, not enough current is reaching pin 8, so it may not switch your TV to the correct AV channel.
viletim on the gamesx forums has designed an alternative RGB Amplifier, looks interesting!
Summary of Components
- 1 x Nintendo compatible RGB Scart lead
- Vero Board (4 tracks by 9 holes)
- 3 x 100uF (or 220uF) 10v Capacitors (your Scart lead may already have these)
- 3 x BF494 Si-N 260MHz Transistors (I’ve read you can use NTE229 instead)
- 3 x 1K5 ohm Resistors
- 2 x 75 ohm Resistors
- Selection of short wires