Today, after managing to get rid of our old queen size mattress, I was lost for something to do so I decided to take another peek at Sabriena’s Super NES and ponder about how to get it to work in Australia when I don’t have the original PSU.
The Australian SNES is 9VAC supply, but the US SNES is 10VDC, and with a proprietary plug too. I can buy an Aussie Sega MegaDrive PSU, and an adaptor to convert it to the proprietary plug, but that’s not a cheap solution. I’ve got plenty of wall warts laying around, what about running it at either 12vdc or 9vdc and soldering a different socket onto the board?
Off to IRC to ask people more knowledgable than I on these matters to try work out a potential approach, where someone quickly dug up the schematics (on a site that I already had bookmarked, from researching my Sega Game Gear).
Looking at the schematic though, it appears as though only some of the supply is regulated to 5v - there’s another output from the power circuit that is nominally 9v that is used for driving the audio amplifiers. In one of the many threads I read, it was basically implied that running at 9v or 12v caused buzzing in the audio, which was dismissed as hogwash, but I (being very uneducated on electronics) can totally see that being plausible by looking at the schematic.
So, the guys in IRC came up with two potential options. First of all, I can buy an adjustable DC-DC convertor (LM2956 based) from China for about a buck. Feed it 12v, get 10v from it, and wire that to the input of the power circuit. Use one of the 12v wall warts I have laying around and off I go.
The other solution they came up with is there’s a chinese seller who sells 10VDC @ 1amp power supplies for about five bucks, with an aussie plug on one end and some sort of small plug on the other. Buy that, buy a socket to fit it, solder that to the board and live happily ever after.
I’m not sure if I trust such a cheap chinese wall wart, but putting extra circuitry in the box of the SNES, as well as the heat generated from bucking 12v down to 10v, it might be the safer solution?