In the home computer market of the 1980s, there were several winners that are still household names four decades later: the Commodore 64, the Apple II and the Sinclair Spectrum, to name a few. But where there are winners, there are bound to be losers as well – the Mattel Aquarius being a good example. A price war between the bigger players, combined with a rather poor hardware design, meant that the Aquarius was discontinued just a few months after its introduction in 1983. However, this makes it exactly the type of obscure machine that [Leaded Solder] likes to tinker with, so he was happy to finally get his hands on a neat specimen listed on eBay. He wrote an interesting blog post detailing his efforts to connect this old beast to a modern TV.
The main issue with the Aquarius is that it only has an RF video output, which results in a rather poor rendition of its already very limited graphics capabilities. Luckily, there is a fix available in the form of a composite A/V adapter that’s an almost plug-and-play upgrade. The only thing you need to do, as [Leaded Solder] illustrates in his blog post, is open up the computer, desolder the RF modulator and solder the A/V adapter in its place. Getting to that point was a bit tricky due to heavy EMI shields that were fixed in place with lots of solder, requiring liberal use of a desoldering iron.
While he had the machine opened up, [Leaded Solder] decided to also replace the original 7805 linear voltage regulator with a switching model, in order to reduce the amount of heat dissipated inside the cramped case. Once all this was done, the Aquarius booted up as usual, but this time with sharp, readible graphics and clear audio.
Interestingly, Mattel used a type of hardware encryption on its peripheral bus in an attempt to prevent unauthorized third-party extensions. Now that the computer is in a usable state, [Leaded Solder] is planning to reverse-engineer this system and figure out how it worked exactly. We’re definitely looking forward to seeing that, since the only homebrew Aquarius hardware we know of used a software trick to get around the lockout.