Aquarius

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Abstract:

I developed the Aquarius RGB to HDMI Adapter Board as an aftermarket upgrade to the stock Aquarius to replace the original RF modulator with a high quality, high resolution output solution. There is no AUDIO output via HDMI, so a separate HDMI Audio Inserter must be used OR a standalone pair of desktop speakers.

I later developed an RGBi to SCART solution, based on a Radofin board included in some Aquarius II models. It has been modernized for easier sourcing, manufacture, and sale. SCART includes AUDIO pins in the connector, so the solution is perfect for users who have a monitor with SCART input.

Background

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 AtariAge.com 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!

Later in 2024 I acquired an Aquarius II from a seller in France and discovered that in addition to the RF output to PAL, it had an official Radofin-branded RGBi to SCART board. I reverse-engineered the PCB and updated it with SMD components. Currently, it only fits in an Aquarius II, but a version for the original Aquarius that fits within the RF modulator space will be developed as well. Note that SCART is a legacy port format that was common in the EU and UK, but is rare in other locations. SCART to HDMI interface boxes are available to simplify this.f

Status (10 JAN 2025)

RGB to SCART - The SMD version is being prototyped and tested.

RGBtoHDMI - The project has been untouched since the hardware shortage of 2022. This was due to unavailability of RasPi Zero units and the CPLD that handles the high speed switching.

Issues

• RGBi to SCART

  • Need to identify older legacy capacitor values.

  • Need to order and test prototype boards.

• RGBtoHDMI

  • 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

Caveats

• RGBi to SCART

  • Current PCB is designed to fit into the Aquarius II.

  • People without a monitor that has a SCART port will need an adapter.

• RGBtoHDMI

  • The installation HAS to be tweaked for each unit to find the best combination of timing and frame offset.

  • The TEA1002 should 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...