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The Nintendo 64 uses a proprietary PSU that takes mains voltage input and outputs 3.3 V and 12 V DC. PSU's from regions where mains voltage is 230 V (such as the EU) were sold as 230 V input while those from regions with 100 or 110 V mains (such as the US and Japan) are specified as only taking 110 V input voltage.

However, it is not uncommon for such step-down PSU's to be able to take both mains voltages. Newer PSU's (for newer consoles) are often labelled 100–240 V. I believe this is due to simplified manufacturing: there is just one internal set of components which can take either and a mains plug is added for whatever region the console is being shipped to.

I opened the Japanese N64 PSU I have and got a glimpse of '250 V' as can be seen in this YouTube video (timestamped). Would this mean, I can safely connect my Japanese PSU to 230 V mains despite the label reading 100 V? Or will this damage the PSU mid to long-term?

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    I think it would be closed on ee.se due to being product usage question. It would have to be reverse-engineered or compared to 230V model if they are identical or not to find out if it can work with 230V. Otherwise, if it says it's not rated for 230V on the label, there is no reason to assume it will work on 230V. It might blow up immediately and damage the console too. Having witnessed a 120VAC device plugged into 240VAC, it worked for like a minute before the main bulk capacitor started venting obnoxious-smelling vapourized electrolyte out.
    – Justme
    Jul 13 at 22:45
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    Looking at the video, the fuse is rated 250V (standard for 20mm fuses) but that doesn’t mean that any other part of the device is.
    – Frog
    Jul 14 at 2:05
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    The issue is that because of the US "split phase 120V" house wiring system the earthing safety requirements on a US 240V supply would be different from the rest of the world. A 240V power supply intended for Japan or Europe would probably "work" if you fitted an appropriate plug, but it would not necessarily meet the US electrical code safety requirements. So there was no commercial reason to produce a different design of 240V supply for the US when 120V is the common standard for low-power devices like a games console., and most rooms in a US house would not have 240V sockets in any case.
    – alephzero
    Jul 14 at 3:07
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    @alephzero How would the earthing requirements be any different? There's three phase and one phase electricity in Europe, with earthed neutral, so that is all the same. Also, the N64 power supply is two-prong non-earthed Class II appliance, so it does not even have earth connection. Most likely it was just cheaper to do two different power supply versions and certify them as needed.
    – Justme
    Jul 14 at 9:38
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    The difference between US style 240V is that US 240V has a center-tapped earth with both supply conductors being hot, while EU 240V usually has one side as an earthed neutral. However unpolarised plugs/sockets are fairly common in Europe, so designers of Euro-spec portable appliances can't assume that the "neutral" wire will actually be a neutral. If an appliance is designed to handle reversed live and neutral it will almost certainly also handle a center tapped supply just as safely. Jul 15 at 1:37
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The supply shown in the video will most likely blow up if you connect it to 230V mains. At 1:08 in the video you see the printing "200V" on the main filter cap. There is no plausible way to build a compact power supply like this that doesn't charge the main filter cap to 1.4 times the mains voltage. Also, as there is only a single cap, the voltage can not be split over multiple capacitors. 1.4 times 230V is around 320V, which will make that cap explode.

This answer is not intended to suggest that if you replace the filter cap with a 400V model, the supply would work at 230V mains. Instead, I try to explain how I deduced that the supply is obviously designed for 120V AC only. I'm very confident that the design voltage of 120V was also considered in other parts of the supply, which will also be damaged if you connect the supply to 230V mains.

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    The reason is that AC voltages unless otherwise specified are usually measured in RMS (root mean square) - that is, a certain mathematical average of the voltage. But capacitors need to be able to handle being charged to the peak AC voltage, which is indeed around 320V for 230V mains.
    – Muzer
    Jul 14 at 9:07
  • This answer is spot on. I decided to watch the video and saw the 200V capacitor too and started to write an answer, but this answer beat me to it.
    – Justme
    Jul 14 at 10:39
  • I have personally blown an Jap N64 by connecting it to 115V (230V stepped down). I can tell you that it will not work with 230V.
    – Aron
    Jul 16 at 1:42
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I can supply an anecdote from 1997-8 that might answer your question.

A friend and I imported a couple of US units to New Zealand so that we could play US region games. As an aside, because the power supply was a removable module, we could slot the NZ power supply into the US unit and play US games, but they still put out NTSC and so ran at a different frame rate to the NZ region versions. I can remember doing an A <-> B test of Super Mario 64 and the US version running just noticeably faster.

Anyway, for whatever reason the US power supply was put back in an N64 at some point, and my friend's girlfriend (who had never been overseas, wasn't technical, etc) plugged the US Type A plug into the Type I NZ wall socket (she had to apply considerable force to bend the pins!) and out came the magic smoke. I think the N64 was ok, just the power supply died.

So in my experience, no, the US power supplies weren't capable of handling international voltages such as 230-240V.

Just to be clear, here are images (from the links above) to show that this is possible (if forced).

Type A plug

Type A (e.g. US) plug

Type I socket

Type I (e.g. NZ) socket

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    Your anecdote is supported by a coarse inspection of the hot side components of the supply. The N64 supply doesn't seem to be "universal mains". Jul 14 at 8:21
  • Precisely the scenario I wish to avoid xD
    – Jan
    Jul 14 at 16:10
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    "US version running just noticeably faster." Hmm I wonder if 50 Hz NZ vs 60 Hz USA line frequency affected timing? Jul 16 at 3:42
  • "out came the magic smoke." ;-) Jul 16 at 3:43
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    @chux-ReinstateMonica: It's because of the output framerates for the PAL/NSTC video standards (which were originally chosen because of the AC frequency). Of course, on a console that modern it didn't have to be that way. There's lots of info if you search for e.g. "pal n64 games slower than ntsc super mario". I found someone's A <-> B comparison video! Jul 16 at 6:30
7

This isn't quite guaranteed, but a good rule of thumb is that transformer-based power supplies are either used for one small voltage range (either 110-120V or 230-250V) or they have a selector switch.

Switch-mode power supplies can be built for a much wider range of input voltages (90-264V is common as this includes all mains voltages used globally, complete with tolerance for broad specifications), but they can also be built for a narrow range, or have a switch. They should always be labelled, sometimes in tiny moulded writing.

Transformer-based power supplies are heavy compared to switch-mode because they use far more copper and iron. So if a power supply is heavy - far more so than a modern one of similar size and output, and it doesn't have a selector switch, it's almost certainly single voltage. If it's light, like a modern laptop PSU, you really need a label. Typically in the 90s and early 2000s, PSUs for devices that might be used while travelling were quite likely to accept a wide range of input voltages, but for devices expected to be used only at home, this was unlikely.

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  • It is guaranteed that the power supply in the video shows it's designed work with 120V mains only, there is no question about it.
    – Justme
    Jul 14 at 10:05
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Usually you can not use any power supply outside the input range it's designed for. Multi-range power supplies will give you a rating of "Input Voltage 100..240V" on it's label. If they have dedicated input voltage rating then your input into the device should really be at that rating. You should always look for a power transformer converting your grid voltage to the right one for your device if you want to use it. There are some power transformers out for your purpose, depending at the power rating something like this here might be right for you: https://www.ebay.com/itm/393398105156?hash=item5b985ab444

Even if it were the other way around opposed to your case: If you would have a 110V power grid and your step-down power supply would deliver proper voltage, it may overload the current consumption and overloading your power supply current-wise on it's primary side.

I would strongly advice, not to use any power supply outside it's Design Input Rating range, you are not only risking your power supply blowing up, it may also damage your device you wanted to power with. And, last but not least harmful, it may even set the whole thing on fire...

Just my 5 cents... ;)

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    You are on the right track here, but due to approval reasons, sometimes you can put an universal power supply module into plastic box that only reads one supply voltage range for the target market, so then in fact the supply will actually work with any mains input range despite what it says on the plastic box. However, this is not the case with this power supply, and it is guaranteed to not work with 220-240V range.
    – Justme
    Jul 16 at 14:00
2

I am not an electronics engineer, however here are a few things I noticed.

At 0:33 in the video you get a brief glimpse of the label on the unit, which reads “AC110V 12VA 50–60Hz”. That is the input voltage the unit is rated for. Strictly speaking, even 110V in the US would be out of spec and nothing is guaranteed here, but that might still be within the tolerance margin. However, 230V is more than twice that voltage.

At 0:54 you can see the entire PCB. The labeling in the top-right corner of the PCB reads “2.5A 125V 5A 125V”. So there are components on the PCB which are designed for 125V, but not for 230V.

Moerover, there is a large transformer in the center of the original power supply (same in the UK knockoff unit he is re-shelling), which appears to do the voltage conversion. Transformer-based power supplies designed to work with both 110V and 230V typically have a voltage selector switch accessible from the outside – the absence of one indicates the device will only operate correctly within a narrow voltage range – 10% more or less may still be OK, but more than 100% is not. Doubling the voltage you feed into the primary side of a transformer will also double the output voltage on the secondary side. Unless there is some more circuitry behind the transformer that further converts the voltage down, you will be running your N64 on twice the voltage it was designed for, with a high risk of frying it. If there is some further circuitry which converts the voltage from the transformer further down, that circuitry needs to be able to handle more than twice the input voltage it would get at 100V – else you will fry the regulating circuitry of your power supply (with possible collateral damage to the N64). Lastly, the transformer needs to be able to handle a doubling of the input voltage – else it might overheat.

And finally, why would the guy in the video go through all the hassle of gutting a 100V power supply and replacing the circuitry with that of a 240V one, when he could simply attach a UK mains plug to the Japanese unit?

While I have seen power supplies that work outside their intended mains voltage (an early 2000s cell phone charger rated for 220–240V, which worked fine on 110V – the other way round is less dangerous), this power supply does not seem to be one of them.

There’s a high risk of frying the power supply, the N64, or both, by running it on 230V. If you can’t find a replacement PSU designed for 230V, your best bet is to get a step-down converter, which will convert 230V mains voltage into the 110V your PSU was built for.

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    The fixed voltage ratio of a transformer doesn't apply to flyback-type switch-mode power supplies. Supplies like the one shown (lightweight late 90s power supplies with less than 70W output power) are most likely to be of that type. The 125V components you noted are fuses on the secondary side (where you only have 3.3V and 12V) and don't indicate anything about the permissible primary side voltages. Your point about the specification is still valid and a good indication that the supply is likely not meant to be used at 230V. Jul 16 at 8:11
  • A couple of reply comments: (1) I haven't yet had a PSU that had an input voltage switch but I have seen plenty that accept 100 to 240 V. As I am also not an electrical engineer (and usually don't feel the need to open them up), I can't tell the different types apart so I wouldn't know that this one is a transformer-based one that only handles a narrow voltage band. (2) Hey, the guy is making Youtube videos, his motive could be anything xD (3) Labels are nice and all but many people's experience with US PS2's say labels can not give the entire picture.
    – Jan
    Jul 16 at 10:02
  • That said, I err on the side of caution and while I have seen a vast number of people plug their 90k series PS2 slim (the one with the internal PSU, which is labelled 110 V only) into 230 V mains, none of whom experienced problems, I am not doing that with my own until I can positively confirm it actually works. ^^
    – Jan
    Jul 16 at 10:04
  • OOI why would 110V in the US be out of spec for a PSU rated AC110V 50-60Hz?
    – psmears
    Jul 16 at 12:47
  • @psmears Technically, US is 60 Hz 120V +/- 6%, and Japan is 100V, and it's 50 Hz or 60 Hz depending on where you live.
    – Justme
    Jul 16 at 13:28

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