This is a way to convert Nintendo Famicom (early model) into video output. Before making this modification, the video board must be assembled. If you haven't, please assemble it here.
Tools required for work
Tools required for remodeling
- Phillips screwdriver
- Soldering iron
- Solder
- Desoldering wire
- Thin nipper without blade spill
- Cellophane tape or polyimide tape
The desoldering wire looks like this.
Nippers, I found this easy to use.If there is a gap at the tip when the nipper blade is closed, it may not be possible to cut completely due to the blade spill, which may make work difficult.
If you can not cut well,I would recommend getting a new one.
Removing the Nintendo Famicom substrate
Open the back cover
Turn the Famicom body over and remove the six screws to remove the back cover.
Removing the connector
Remove the connector from the controller.
Removing the board
Remove the screws of 4 places of RF board and 4 places of Famicom main board.
Removing switch wiring
Remove the cable connecting the red and white switches to the RF board, which is soldered.
Use a desoldering wire to remove the solder.
Separate the RF substrate
Separate the Famicom main substrate and RF substrate. Cut with the cable on the mainboard side.
Cut with nippers.
Remove the wires remaining after cutting with a soldering iron. (If it is difficult, you can leave it as is)
Modifying the Famicom substrate
Add a capacitor
The video of the NES contains noise generated by memory access. In the case of the old RF connection (connected to the antenna wire), this noise was not very noticeable due to the degradation of the image caused by RF. However, when the video circuitry is converted to the new video circuitry, the noise, which was not noticeable until now, becomes more noticeable.
Therefore, I take measures to prevent the noise of the memory access from being mixed in as much as possible. There are two countermeasures to this.
- Add capacitors to reduce power supply voltage fluctuations
- Extract signal directly from video output pin
First, add a capacitor for noise suppression .
First condenser
Install the first capacitor at this place in the photo.
Cut off the excess lead with a nipper.
Second condenser
Connect the ends of the arrows in the photo with capacitors. Deform the shape of the capacitor so that the foot of the capacitor does not touch the silver solder around it, and then attach it. If it seems difficult, you don't need to install this second capacitor.
Attach the capacitor like this.
Cutting IC pins
This is the second measure against noise. When video and audio signals pass through the Nintendo Famicom mainboard, noise due to memory access generated by wiring passing close to the wiring will be mixed in. In the case of video images, vertical and diagonal stripe noises are introduced, and a buzzing sound is mixed in the audio signal.
In order to get a clear image and clear audio signal, the signal is modified to take out the signal directly from each output pin of the IC in order to prevent these noises from getting mixed in as much as possible.
Cut the leads on the substrate side of the IC pins and disconnect the IC from the substrate. Note that it is not the leads on the package side of the IC, but the leads on the substrate side that are detached.
Also, if you bend the separated lead upward from the horizontal, it will be removed due to metal fatigue, so Please be careful not to bend too much .
Video signal
Separate the pin at the upper right corner of the IC called RP2C02 from the substrate.
With the flat surface of the nipper blade facing down, insert the cutting edge between the IC pins and cut. If the blade is spilled, it will not cut well, but twisting or forcibly moving it will damage the board and IC pins. Let's cut carefully without moving as much as possible.
Once cut, lift the pin horizontally. Do not lift any more upwards.
Audio signal
Disconnect the two pins in the lower left corner of the RP2A03 IC from the board.
Carefully cut the leads on the substrate, one pin at a time.
Once both of the two pins are separated from the substrate, lift them horizontally. Don't lift the pin to an angle above the horizontal.
Prepare the shield wire
For video signal
Two shielded wires, a thin wire and a thick wire, are included. Use the thinner type (1 core type) for the video signal.
Peel off 10 mm of the black coating on the tip of the shield wire.Peel off 5 mm of the white coating inside it. Twist each wire, then soak it with solder and plate it.
The other one will also be processed. In this case, we don't need the wire for the shield part, so we cut it from the root. Cut the white line to about 3mm after solder plating.
For audio signals
Process the thicker shield wire (2-core type). It's the same procedure as before.
Peel off one black coating 10mm. Peel off 5 mm of the black and white wire covering in it.
On the other one, peel off 10 mm of the black coating, and 5 mm of the white and black wire inside. Twist each wire and apply solder plating. The outer shield wire is unnecessary, so cut it from the root.
Cut the white and black lines to about 3mm.
This completes the cable processing.
Wiring to video board
Connect the video substrate and the IC pin of the Famicom main unit with the shield wire processed earlier.
Video signal
Use the thin cable for the video signal. Solder the white wire and shield wire of this cable to the video substrate. Insert the white wire into "VIDEO" and the seed wire into GND, and solder.
Only one pin of the Famicom main board has been separated. Solder the other white wire to the pin of the IC.
Secure the cable to the IC with cellophane tape so that it does not move. This is to prevent the pins from bending or being removed when the cable is put back into the case. Polyimide tape is used so that you can see how to apply cellophane tape in the photo.
Audio signal
Use the thicker cable for audio signals. Insert the white wire into “A # 1”, the seed wire into GND, and the black wire into “A # 2” and solder.
Solder the other wire to the two pins of the IC on the NintendoFamicom board. The pin at the end is white, and the black wire is soldered to the second pin.
Secure the cable on the IC with cellophane tape as shown in the photo below to prevent the cable from moving.
Power switch
Attach the red and white cables to which the power switch of the main unit is connected to the video board. The left side of the hole is red and the right side is white.
That is all for the connection of the shield wire.
The video board looks like this.
Put the board in the case
Return parts to the case
At First, Return the Famicom main board to the case.
Next, put the video board.
Insert the Famicom controller cable.
Tighten the eight screws to secure each board.
Wiring Famicom board and video board
Connect the Famicom main board and the video board with jumper wires (resistance leads).
As shown in the picture, connect "AUDIO", "+ 5V", and "GND" to the Famicom board.
Make sure that you make the same connections as shown in the picture so that you don't accidentally connect to the next pin.
Connect connector
Connect the controller connector to the Famicom connector.
Put in cables
Route and store the cable as shown in the picture.
The shield wire coming out of the video board bypasses the screw holes at the upper left and upper right of the case and passes over the main board. If you do not bypass the screw holes, you will catch on the cable when removing the cassette.
Also, if you pass over the blue cartridge connector, the lid will not be closed. It is good to fix it with tape on the main board.
Screw back case
Close the back cover and tighten the screws.
Modification completed
Connect the video cable and confirm that it is reflected on the TV. In the above picture, the video is projected on a computer with a capture cable.
https://en.kohacraft.com/archives/modify-nintendo-famicom-late-model-to-video-output-with-fcav.html
