"AC" port on a Colecovision???
... and the -5V?
Yes, I know I always say "AC" port, even if it's totally wrong... as most people think of the power connector
The -5V are being created by a DC-DC Inverter.
Are you making a plug with the DC-DC converters in a block of some sort that has +5V from the USB as it's sole power source? Can it even supply enough current? I'm just asking, I've never measured the amp draw on a CV, but The power supply was pretty large, and I do know that it was insufficient with one of the add on modules...
Well, I only have a normal CV for testing here (no addons), and a flashcart (which uses more power than a normal game, so it's a good test).
The prototype samples are on the way to me, so I can test them soon
The CV power supply provides 0.9A with 5V (= 4.5W), 0.1A with -5V (= 0.5W) and 0.3A with 12V (= 3.6W). Alltogether, that's 8.6W.
If you use a 2A USB-Adaptor, you have 5V * 2A = 10W in theory, so that's already more than the CV Power supply provides.
There are even 3A Adaptors out there, which can provide 15W.
Sure, you've got a bit of loss with the conversions, but these losses are known thanks to the datasheets. 1.8A should be enough to provide the same power the CV power supply provides.
We'll find out how well it works in reality as soon as the adaptors arrive here