I was just enjoying the thread about how the SFC sold without cables, and got to the mention that "every mainstream console in Japan at that time used the same 9V 1A PSU so why should you get more PSUs to do the same job as one would do. Although Nintendo messed up after this by making every other console after that have hardwired and different PSUs." Um... with unregulated supplies, is there any material difference between 10V 850mA and 9V 1A? Was Nintendo shipping the same old bits inside? I /had/ been wondering why my NTSC SNES used such a strange voltage, when it is so close to the commonplace 9V, and there's a 7805 inside anyway, serving everything but the audio amps. But I'd neglected to consider marketing. Coincidentally, I found the wrong supply for my SNES at the thrift today. I should have read more carefully, but I still would have bought it.
Basically, it's 10V because that's what the original Famicom used. As was discussed in that other thread, Nintendo decided to make the SFC use the same power adapter as the Famicom (which is why it's "HVC-002" rather than "SHVC-002") - they also decided to make the PCB inside the US SNES exactly the same as the Japanese one despite the different plastics between the two units. This also means that you can't use a US NES power adapter (which is AC) on a US SNES (which is DC) - but you can use a Japanese NES/SNES power unit on it. To further add to the confusion, the PAL SNES is AC, so you can run a PAL SNES on a US NES adapter, but not vice versa.
Yup! All good information and always worth re-summarizing. What I'm wondering is if Nintendo's 10V 850mA were just re-cased 9V 1A hardware. See what I'm getting at? With unregulated supply I'm not sure there's a way to tell without unwinding the transformers to count the turns.
I imagine it's a different transformer - when you are making stuff in that sort of quantity you can ask for any turns ratio you want. I don't know why they chose 10V, though - even a full current a 7805 only needs 2V of voltage headroom. All I can guess is that the VHF modulator needed a significantly higher voltage than the rest of the circuit.
