Based on the "FCAV" (Famicom Audio Visual) kit that I made for converting the NES（Nintendo Famicom）to a video output, I have made a substrate with pre-assembled components so that you can more easily convert the NES to a video output.
- What is FCAV?
- Prototype of FCAV mounted substrate
- A little bit of mass production
- Mounted FCAV has been completed !
What is FCAV?
The regular NES (Nintendo Famicom) was designed to be connected to a TV antenna to play games on the TV, and you can't connect it to your current TV.
So, I made a modification kit before that could connect the Nintendo Famicom to a TV.
Note : This kit can only be used with the Japanese version of Nintendo Famicom, so it should be labeled "Nintendo Famicom" instead of "NES.".
When you modify the Nintendo Famicom with this kit, the Famicom becomes a video and audio output with yellow, red, and white connectors. This allows you to plug it into your TV or use video capture to show your game on your computer.
Furthermore, although the Famicom's sound is monaural, the special circuit of this kit converts it into a stereo sound with a natural feel, allowing you to enjoy a more realistic game.
Famicom modification by FACV in two stages
1. Assemble the substrate
The parts are soldered to the FCAV substrate to complete the process.
2. Modifying the Famicom
The RF conversion substrate built into the NES is removed and replaced with the FCAV substrate.
I wish it could be modified more easily
The FCAV board contains high-quality video circuits and natural pseudo-stereo sound circuits, so there are a lot of parts. We thought it would be much easier to modify this board by making it pre-assembled.
Prototype of FCAV mounted substrate
Designed with KiCad
So, I will design the substrate for mounting. All parts are surface-mounted, except for connectors that require strength.
The details of how to use KiCad are written in an appendix book called "Full Spec Board Software KiCad 5.1 Guide Book" in the August 2019 issue of Transistor Technology, so it is convenient to have it handy.
The NJM2580, the video amplifier IC used in FCAV, was not available for surface mounting, so I changed it to a video IC that is available and has good specifications. This high performance video amplifier is 1080i/720p compatible and faithfully reproduces the video signal waveform of the Nintendo Famicom.
As for the electrolytic capacitor, I selected the parts made by Japanese manufacturer with a little care.
The substrate arrives
I had the substrate and stencils made by JLCPCB.
Make a 1mm hole in the same position on both the stencil and the substrate. By inserting a thumbtack into this hole, the board and the stencil can be aligned in an instant, and it prevents the stencil from shifting when squeegeeing. It's very convenient. Then, put the solder paste on the back of the stencil.
Print solder paste on the substrate using membership cards, point cards, credit cards, etc.
It printed beautifully.
The solder paste "CHIPQUIK TS391LT50" which I started to use recently and can be stored at room temperature is quite good. It transfers nicely and the stencil is less clogged.
The electric vacuum pick HAKKO 394 is used to mount the parts.
Using this vacuum pick is a lot easier to mount than using tweezers. I can no longer go back to using tweezers.
Thanks to the electric vacuum pick, I was able to finish mounting the parts in no time.
The substrate is reflowed in Tescom's convection oven after the parts have been mounted. Suitable temperatures and times for reflow are 3 minutes at 120 degrees Celsius, 1 minute at 140 degrees Celsius, and 1 minute at 160 degrees Celsius. This setting is a nice temperature profile for low temperature lead-free solders.
This convection oven seems to be popular and is in short supply, so check it out if you find it.
It's a perfect finish.
Modifying the Famicom
It worked properly. Both video and audio are fine. The prototype was a success, so I'm going to mass produce it a bit.
A little bit of mass production
Even if I call it mass production, I will make less than 20 pieces. Really the vacuum pick HAKKO 394 is great.
The mounting was completed in a short time.
The TESCOM convection oven holds four toasts, so it holds four 10cm x 10cm substrates. This time, 8 substrates can be reflowed at the same time.
The connectors are soldered by hand to the substrate made by reflow soldering, and the substrate mounting is complete.
I made a jig to check that the video and audio were being processed properly. I made a MAX V CPLD board before, and it generates NTSC color bar and 3ch (right, left and center) beep signal. This is the MAX V CPLD board that I used.
I use this for the test pins used on the jig.
This has a spring built into the pin, so even if the pins are slightly uneven, they will contact properly. There is a socket for this pin, which is soldered to the substrate and used to set the test pin.
The video and audio signals output from the FCAV are captured by the MacBook via a video capture cable. I used OBS Studio as the capture software.
Take a look at the photo above. You can see the color bar on the MacBook in the back left. Now I can check the video. The level meter is displayed by the function of the MacBook capture software OBS Studio. This is the audio signal. These signals could be confirmed both by sight and by ear. The substrate check is now complete. Thanks to the jig, I was able to inspect it quickly.
Mounted FCAV has been completed !
The FCAV board has been completed with parts mounted. Now you can output video from the NES more easily.
If you want to play NES with your current TV, please use it.