Coyo. Yet again i find myself answering your odyssey questions
The detachable controller system that i have has the following specs on the ac
Output 11.5VAC, 400 MA
Input 115 VAC, 60 HZ 12 W
It is indeed a 3.5 mm jack style adaptor. I do beleive that you can find a universal adaptor at Radio shack that will work. Or sometimes you can find just the adaptor on ebay. I do like this system .Congrats on finding one.
I dont think you can open the box end easily. You may be able to pry it open if you want to try. You seem resourceful enough to try it lol
By the way i have heard that you can use the Atari 2600 Power Supply but havent tried it myself but by looking at my service manual for the Odyssey 2 it seems plausible