Do I need a power converter- for Japanese synths in the US?

[virtualanalog]

I just got a Japanese SH-101 and an electribe, and I cant wait to test them out. I don't want to plug them in till I'm sure that I wont damage them.

I've read that people use japanese electronics in the states without any problems, but do I need a step down converter?

The US runs at around 110-120v I think, and Japan runs on 100v.

I checked the adapters for the synths that I already have and they say 120v. The adapters that came with the Japanese synths both have 100v marked on them.

What should I do?

[dougt]

No don't use the 100V adapters. Just get a couple new 9V neg tip 500mA adapters and you'll be good to go...

[Electroluver]

Can someone please give us a definitive answer to this question? I've been spending $25 a pop on 120v-100v converters. Some people claim that the internal circuitry is designed to take a +15/-10 power drop due to the spikes in current experienced in Japan. Not to mention, many of these synths are destined to the US and they may be using the exact same power supply.

I wouldn't risk running my Jupiter 4 without a step down converter, but what about a Yamaha CS-5/CS-10? Upon opening the chassis, I often see 125V written around the power supply or +15/-10. Then there are those synths that you can internally change by re soldering a power lead on the board.

[Electroluver]

bump.

[nathanscribe]

There's a thread buried somewhere that deal with this.

Basically, if your synth uses an adapter, buy a local one that provides the same output. If your synth runs right off the mains, it partly depends on the way the power supply is set up - what kind of regulation is being used, and how close to the limit they are being run. For example, I've run my Japanese CS-15 here in the UK on a 240-120 convertor and it's fine. I know I'm pushing the regulator close to its limit but till I find the time to replace the transformer it'll have to do. My CS-5 had a switch for selecting a range of voltages, from 100V to 240V, so that was a non-issue. Other gear has internal selection too, such as 240/120 or 220/240 (LinnDrum and Akai MX73 respectively). If you have a switch either on the outside or inside of a unit, use it.

Some transformers will have different tags for different inputs. You'd need the service notes for that unit to check how to wire them, but if the manufacturer has used a generic transformer that can be wired for different countries, it can be rewired to suit. I even have one synth where the first owner imported it from Japan and had a 240-100 step-down installed inside. It's been working for 30 years.

It migght be worth learning about how power supplies work, examining the schematics for easch unit, and using some judgement on whether you can get away without a stepdown or not. Naturally I'd say it would be best to use the correct supply, but if it's not possible, you might get away with it.

[Composition86]

Hi, this is the problem that I'm trying to solve in the last two weeks.
I have a japanese Roland SH2, I use a 220->110 power converter to play it, easy to find here and really cheap. I measured the tension in order to assure myself that I would have 110V on out, that's the first thing I did.
110V is quite a good voltage because is about 10V under the maximum tolerance of the sh2, this is what some techicians said after reading the schematics.
So I'm using it without any issue, keeping it on up to 1 - 1:30 hours.

There is an other solution: modify your converter.
You can either cut the coil, in order to raise the voltage at a desidered value (I tried, but it is impossible for me, because primary and secondary are wrapped on each other, so don't try if you are not expert) or insert a resistance inside the converter.

This second solution is absolutely inelegant, but it should works fine: in fact this kind of keyboards are not amplified, so there won't be any problem with variable tension, in theory. In practice I should measure a few tensions inside the sh2, but I would avoid it, I'm not that expert.
I would use a 100 Ohm 2-3W resistor, please anyone tell me if it is a good solution!

[Hair]

I know this isn't the most relevant for the topic since these things aren't as fragile as vintage synths, but me and the rest of the country have no problem just plugging in 110V Japanese arcade machines into our 120V american outlets, same thing holds true with Japanese PS2s - plug and play, nothing blows up.

Edit: to be clear, I don't mean just because PS2s are presumably made in Japan that they're designed to run off 110V, I mean Japanese PS2s for the Japanese market which people import in order to play games that don't get released here (and don't want to bother with modchips etc)

[Bitexion]

As long as the adapter gives out enough Watts, and the voltage is correct, you should be able to use it with no fear of blowing anything.

The back of the synth should have a plate somewhere telling "120V/60W" or something.
Power (W)=U (voltage) * I (ampere)

Just don't do what I did with my japanese SQ-80, forgot to use the adapter it came with because I wanted to test it soooo badly after unwrapping. We use 230V in Norway..so the synth just gave a sad "piiiuuuuu" sound in the speakers when I flipped the On switch. Luckily it has a big fuse on the PSU that is reacable from the outside..swapped that out, used the correct adapter and woo, lights and sound.

[nathanscribe]

As long as the adapter gives out enough Watts, and the voltage is correct, you should be able to use it with no fear of blowing anything.

I think the point of the questions here is whether it is safe to not use a voltage convertor of the correct voltage if the supply requirements are within a certain range of the intended.

[Electroluver]

Most Japanese synths have the same schematics for North American. Furthermore, when I look at the back/inside of the synths, they look like they have the ability to run North American current (eg. +15/-5 v, or 125v fuse)
Still, it comes down to the current these synths were designed to take. If you plug a Japanese hair dryer into a North American plug output, the power is way too much for the hair dyer to handle and it doesn't work properly and will break. Does this apply to synths as well?

[nathanscribe]

Most Japanese synths have the same schematics for North American.

The synth will have the same schematic wherever it goes. The power supply part of the schematic will have either regional variations as separate items, or indications on the diagram as to local changes.

Furthermore, when I look at the back/inside of the synths, they look like they have the ability to run North American current (eg. +15/-5 v, or 125v fuse)

This makes no sense. "+15/-5V" will be the intended output voltage (not current, which is measured in amps/milliamps) of the power supply - the DC which goes to the rest of the synth. The output of the supply may or may not depend on the exact input, depending on how it works. A regulated supply will tolerate variations on its input, but how much it will tolerate depends on the design.

If I were you I'd keep buying those convertors till you learn more about electricity and/or electronics.

[HideawayStudio]

Can someone please give us a definitive answer to this question? I've been spending $25 a pop on 120v-100v converters. Some people claim that the internal circuitry is designed to take a +15/-10 power drop due to the spikes in current experienced in Japan. Not to mention, many of these synths are destined to the US and they may be using the exact same power supply.

I wouldn't risk running my Jupiter 4 without a step down converter, but what about a Yamaha CS-5/CS-10? Upon opening the chassis, I often see 125V written around the power supply or +15/-10. Then there are those synths that you can internally change by re soldering a power lead on the board.

OK OK.... this is getting a little out of hand. The Japanese market has always been a tad difficult when it comes to the mains as it's notoriously bad! It is true that the nominal voltage is often stated as being 90 volts BUT it is known to vary much more from town to town or even out of the same socket than the US mains. In fact the frequency can vary between 50 and 60Hz too!

This means that kit designed for the Japanese market must be capable of handling quite a voltage range without ill effect. Taking this into account I would expect any decently designed piece of electronic equipment built for a Japanese end market to work fine on US mains.

Even worse than this each household in Japan is often fed off a fairly small transformer which makes the domestic mains even more prone to voltage variation under load and spikes.

In reality most vintage synths may run just a tad hotter or slightly closer to their max specs for capacitors etc on unregulated secondaries - either way I would not be too concerned. This is NOT the case for any gear featuring synchronous motors - eg. a tone wheel organ as the motor speed is locked to the mains frequency.

Obviously where this IS a problem is running Japanese gear in Europe where the nominal voltage is 230V - in this case most synths will still be fine on a 230 to 120V autotransformer suitable for the US market.

In the OP's case he has an SH-101 which does not have a built in PSU and simply uses a "wall wart" style PSU. I agree with the second poster that the best solution is simply to discard the original external PSU and purchase a good quality PSU with the correct output voltage, polarity and DC power jack. There is nothing special about the original PSU bundled with the SH-101.