Power Adapter for American SNES

If you want to power your Japanese Super Famicom, it’s easy – just use a Sega Mega Drive 1 Power Supply, that’s it!

Having just picked up a USA SNES, without a power pack I wanted a cheap way of powering it.  It needs 10v DC and at least 850mA, I already have a Mega Drive 1 Power Supply which says it’s 10v DC and 1200mA, perfect except for the power plug it self.

Here’s 2 methods to that I’ve tried.

Method One

Maplin sells a power plug which fits the socket on the rear of the console, it’s part number AR28F – it’s marked as being a “DC Jack 7mm X 1mm” (they also call it type R).  You can also get a 2.1mm inline socket (JK11M – “DC Power Line Socket 2.1mm”) and a cable with a socket that AR28F fits onto to (AQ81 – “Power Adaptor Lead”).  With these parts you can solder up a converter to let you use a Mega Drive 1 PSU on your USA SNES.

All the parts

That’s all the parts, take a look at the power plug, you’ll see that one side has a + the other has a – on it.  If you look at where the plug connects to the power lead you’ll see that it has TIP written on one side of it.  The USA SNES expects the TIP (or centre) of the power plug to be Negative, so connect the power plug to the cable with the – lined up with TIP

Getting the polarity right

Decide how long you want the lead to be and cut it to length, remember to put the plastic casing of the 2.1mm power socket on the cable ready for when you’ve finished soldering.  Split the two wires, strip them to show a small bit of bare wire, twist the wires and tin them by melting a small bit of solder to bare wire (I usually strip too much wire on purpose, this helps when twisting and tinning, then I cut it back much shorter)

Wires prepared

Find something to hold the power socket, and add a bit of solder to where you need to attach the wires.  Then it’s simply a case of soldering the correct wire on, the cable from Maplin has a white line (white tracer) along one of the wires, this is normally used to mark the wire as being Positive.  The Mega Drive 1 PSU is centre (or tip!) negative, so solder the black wire to the short middle contact, and the black wire with with tracer to the larger outer contact.

Socket ready to solder

2.1mm inline socket in place

Finally, the finished product, also useful because you can buy individual or a pack of different sized plugs which may work on other consoles!

Finished converter cable

Method Two

I also wanted to try something different, I already had a couple of 2.1mm power sockets, one a board mount one, the other a chassis mount one.  I wanted to replace the socket that was already on the board, but I couldn’t get to it!  I just couldn’t remove the plastic panel at the back of the console!

So I decided to use the chassis mount 2.1mm socket that I had, but I didn’t want to drill any holes to mount it.  So I decided to remove the RF Unit – I wasn’t going to use it, and then I’d have the perfect sized hole for the power socket.

The usual applies for taking apart a SNES, make sure you switch it on after you have unplugged it (to discharge it), you also need a GameBit.  Once you have it in pieces, and have the motherboard out I found it a lot easier to remove the Metal Heatsink that’s attached to the 7805 voltage regulator.

The RF Unit is very easy to remove, it’s just 3 screws (highlighted below, actually, it’s only 2, but I can’t remember which 2!) and 4 points (I’ve drawn a blue rectangle around them) to desolder.

Removing the RF Unit

Once you’ve got it desoldered, it’s time to wire up your socket.  You have to know the polarity that the SNES expects and the Mega Drive PSU delivers.  The Mega Drive PSU is centre negative, which also happens to be what the SNES expects!  If you don’t know how your socket should be wired, but you have multimeter then plug the MD1 PSU into the socket and then measure the voltage on the pins.  Here’s how I wired up my socket so that the centre pin is negative, and the outer contact is positve.

2.1mm power socket

And here’s the points on the bottom of the SNES board, showing the positive and negative.  Now it’s easy, I simply soldered 2 wires to the relevant contacts on the socket, fitted it to the chassis, cut them to length and then soldered them to the bottom of the motherboard.  It really is that easy.

The info on making the power adapter lead was found on either Bordersdown or Rllmuk, I can’t remember which as I saved a copy of it years ago before I knew I would be posting it on the web.  I decided to fit the socket though as I had one spare.

The finished article

Why run a USA SNES?  In my opinion it is ugly, the EURO SNES and the Japanese Super Famicom are extremely nice, so nice I couldn’t bring myself to hack the Cartridge Slot up (I’m not too good at cutting stuff like this).  BUT, if you remove the tabs in the cart slot on a USA SNES then you can instantly play all those great SFC carts with NO other modifications, you don’t have do do anything to play Mario RPG.  If you want to play PAL games then you can of course fit normal switches for the mod, or do a SuperCIC mod.