RGB to hdmi video adapter

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The Aquarius RGB to HDMI Adapter Board will be an after-market upgrade to the stock Aquarius that replaces the original RF modulator with a high quality, high resolution output solution. For now, there is no AUDIO output via HDMI, so a separate HDMI Audio Inserter must be used OR a standalone pair of desktop speakers.


After I completed the Aquarius Composite Video Adapter, I decided the next step was to try to improve the output from the Aquarius to display on monitors that separated the RGB signals for higher quality signal. I began reviewing older posts from Bruce Abbott on the forums, and found that he had developed a working model in 2014. It had a few problems, namely that characters with full-height pixels in them would render with a faint vertical bar on their left side. He resolved this issue later in about 2017 by adding a 74LS165 shift register on the INPUT side... dubbed the V4+ it included both RGB and composite out through a custom DIN connector. That effort was progressing SLOWLY and unfruitfully. I even went so far as to have a set of prototype PCBs made, to no avail.

One day a video for the Amiga RGBtoHDMI adapter came across my YouTube feed. I traced the sources back to Hoglet67's RGBtoHDMI project, which uses a RaspberryPi Zero with a custom Pi Hat with a CPLD that samples video pulses from legacy RGB video sources and renders them into the Pi's graphics buffer and out through the mini-HDMI port. I had a set of their boards printed, sourced the parts, made the SMD solder mask, and built one. And it worked!

Status (19 APR 2021)

First prototype (v1.0a) successfully installed in a client's machine. Updates/tweaks will be made in v1.0b, but existing boards will be used until they are gone.

Issues (19 APR 2021)

  • C1 10uF SMT capacitor shorts out on RPi's mini HDMI port

    • v1.0a Fix: insulate with Kapton tape

    • v1.0b Fix: rework position of cap right, above fourth top pin on CPLD

  • CPLD index mark is not visible due to via drill

    • v1.0a Fix: know that the CPLD index is in the upper left of the SMT profile

    • v1.0b Fix: move via or add more prominent silkscreen dot inside CPLD area

  • Soldermask covers copper jumpers that enable CPLD programming; looks like they AREN'T connected when they are

    • v1.0a Fix: ignore or carefully scrape off solder mask AND/OR add solder blob across pads

    • v1.0b Fix: remove solder mask over those traces

  • Missing R7 rom core design; brings GPIO0 low with a 1k resistor

    • v1.0a Fix: bodge a 1/4w 1K resistor between pins 7 & 8 on the inside, non-reset row, bottom of the board

    • v1.0b Fix: add R6, a 0408 1k SMT resistor above pins 7 & 8 on the inside, non-reset row, TOP of board


  • The TEA1002 has to be removed and soldered to a small riser PCB which gives a pin header for the necessary RGB signals. At some point, the TEA1002 MIGHT not be needed at all, but testing will have to be done for that.

  • Audio out comes from a 3.5mm / 1/8" audio jack on the daughtercard. A slimline stereo audio cable is trailed out the TV out port on the Aquarius, and can be attached to speakers or to an HDMI Audio Inserter device.

  • A mini-HDMI cable is included and plugs into an exposed mini-HDMI jack in the TV out port on the Aquarius.

  • Not all HDMI TVs/Monitors behave the same. Some tweaking of the settings sometimes has to occur before closing up the Aquarius.

Build Instructions

Let's not get ahead of ourselves...