Internal AC Adapter

Hey guys, I just recently got bit by the retro console modding bug, and I'm working on a old NES I inherited. I realize that this question is better off on the Retro Mod forums, but I'm having trouble getting registered over there, so I'd figure I'd just as you guys and see if anyone here can help.

We all know the NES has a ton of unused space in the case, and I was was thinking, I might be able to tear down an AC adapter and sick it in there, so that I can have a nice clean plug on the back like the playstation or saturn. I know adapters can cause an issue with heat, but I'm not planning on overclocking, or doing any other hardware mods on this. I also heard that any adapter that outputs 9-12v and ~1A should be fine as well. The other thing I'm wondering, is could I solder the output it directly to the board, say directly behind the original AC plug? Is there any extra mojo that happens before the main board receives power?

Let me know your thoughts, thanks a bunch.

There's a 7805 regulator providing 5.0 V to most of the system that it should be possible to bypass. If you can replace this with a more modern, more efficient source of 5.0 V, such as the switched-mode power supply in a smartphone charger, you might be able to fit it in the NES Control Deck's chassis without much problem.

But I do seem to remember at least one part of the NES depending on the 9 V AC input. Was it the RF modulator?

Yes, the RF adapter relies on the unregulated ≈+13VDC out of the bridge rectifier. Nothing else seems to.


Do note that putting the power adapter inside the NES case is a bad idea for fire safety/code reasons. (A device that has more than 50V inside of it must be enclosed in something fire retardant. For example, one of the cost savings from the original PS1 with its integral power supply to the thin PSone was removing fire retardant from the case.

Here in Brazil, some of the SEGA consoles released by TecToy (most notably the Master System III, which was our version of the Master System II) had internal power adapters. I don't know if the same regulations apply here (probably not), but I don't think these consoles were known for catching fire.

I believe this is a UL requirement, not a US law thing. Anything that's actually UL licensed (not being lied about) and has something above 50V in it must be put in a fireproof (e.g. metal) or fire retardant case (by adding certain chemicals to the plastic).

Whether TecToy bothered to manufacture their products in a matter that could be UL certified is another question.

Then put the whole dang phone charger case in there too. If it's UL listed, then everything that handles 120 V is in a flame-retardant inner case.

Tepples, you're saying a regular tiny USB power adapter for my galaxy would work?

Just did some research for those interested. The charger for the Samsung Galaxy note has an output the comes really close to the NES factory adapter. It's a 9v and a ~1.6A. Even better it's only $10 new. On any USB the 2 outside pins should be the positive and the ground. Though I'm sure I'm not tellin' you guys anything new.

So it sounds like I can wire this directly to the board. That'd be great because I really don't want to crack open that box that has the RF modulator in it. But where would I solder, and what joint would be the positive and what side would be the ground?

Also I'm pretty sure that SNES and NES consoles are already fire retardant, it's the reason they both turn yellow when exposed to sunlight.

An ordinary 5V 500mA USB power adapter would barely work... be warned that it's very borderline. (In my measurements, the NES draws about 350mA, and whatever cartridge you add will draw more).

If you bypass the 7805 (be sure to add or repurpose the power switch), you can just supply +5V directly.

I'm pretty sure those things only output 9V when they detect a compatible device, and 5V otherwise.

A 5 V USB adapter rated for 1000 mA, such as that provided with certain tablets, might work even better.