composite video adapter v2.0 - Prebuilt

Support our site! Visit our favorite PCB manufacturer, $2 JLCPCB!


The Aquarius Composite Video Adapter Board v2.1 is an after-market upgrade to the stock Aquarius that replaces the original RF modulator with a smaller, pre-built card that uses smaller, surface-mount components. The adapter will work with either PAL or NTSC systems.


After completing v1.1 of the Aquarius Composite Video Board (DIY version), I had many people asking about a pre-built solution, or at least one that was a little less-expensive to make than the first version. I also knew that I could improve the footprint of the board to make it smaller, easier to install, and serve as a potential starting point for an all-in-one Aquarius video board that would eventually have both composite and RGB outputs.


The Aquarius Composite Video Adapter Board v2.0 is in development, and will be available for purchase when testing is complete.


Development Details

The SMD (surface mount) version of the AD812 video amplifier chip is about US$2.00 less than the through-hole version, and is 25% smaller, so it made sense to transition to this version of the chip moving forward. The electrolytic capacitors used in the DIY version are also larger and more expensive, so I took the opportunity to transition to SMD versions of them as well. Finally, since I was reducing size and cost on the other components, I transitioned the resistors to 0603 1/10W SMD versions too. This resulted in a footprint that was almost HALF the size of the original.

In reducing the footprint of the board, I removed the need to use one of the mounting points, so users will only have to use three of the original RF box slots as mounts. The breakaway spacers have also been updated so that they "notch" into points near the mounts to simplify spacing the CVA board away from the Aquarius motherboard. The spacers can still be "stacked" as a spacer, but the notches allow less "fiddling" now.

Build Instructions

Below are videos of the process of installing the original Aquarius Composite Video Adapter board. The Prebuilt version will be simpler, and videos for that process will be completed after the product is complete.

1. motherboard removal

First, you have to remove the Aquarius motherboard from it's case.

2. RF Shield removal

Next, you need to remove the RF shield that encases the motherboard.

3. RF Modulator removal

Next, removal of the stock RF modulator is necessary.

This video also shows removal of the 7805 power regulator so it can be replaced with a modern equivalent, which is optional (but a good idea).

4. Building the Adapter Board

The board is now pre-built, so no assembly is required.

5. installing the adapter board

Installation of the pre-built board is nearly identical to the DIY board, so use this video as a GENERAL guide.

6. testing the install

Finally, you need to test your installation.

OPTIONAL: 7805 Replacement

Instructions on installing an OKI-78SR-5/1.5-W36H-C replacement for the 7805. Do this after Step 3, above.

optional: replacing the capacitors

Instructions on replacing the electrolytic capacitors on the Aquarius. Do this after Step 3, above.

More details on our Aquarius Capacitor Replacement page.


  • No video signal - Not all 3.5mm / 1/8" AV cables are wired the same. Check the image to the left to verify the pinouts for the cable you're using.

    • If you want to bypass the cable and test directly with a hacked RCA video cable, solder/clip the video positive signal (center) to the left test pad (labeled COMP), and the ground (outer) to the center test pad (labeled GND), and twist the remaining wires together and solder to the right test pad (labeled AUD). If you still get no signal, check your work and soldering.

  • Still in development - The circuitry on the CVA is fairly simple, so there's little that can go wrong. As we find quirks or problems, I'll post them here.