Using 100V Japanese-Made Synths in the U.S.

Aaron2 · Post by **Aaron2** » Tue May 15, 2012 5:26 am

Hi everybody. I'm new here. I have a question about using synths made for the Japanese market. As you know, they were designed to run on 100V AC current. Here in the U.S., we have 120V current.

Does anyone have experience using made-for-the-Japanese-market synths in the U.S.? Does it cause any long-term harm the synth to run it on 120V U.S. house current?

If it matters, the synth in question is a Korg Poly-61. This particular model was apparently designed to run on 50 or 60Hz, so that doesn't seem to be an issue.

Any insight is appreciated. Thanks!

Aaron

Hair · Post by **Hair** » Tue May 15, 2012 6:19 am

I'm sure someone with more experience with synths in particular can chime in, but I seem to recall that it's supposed to be fine.

Fwiw, I've played on many imported Japanese-market arcade game cabinets that are simply plugged into outlets here in the US and work fine - in fact, I own one!

ApolloBoy · Post by **ApolloBoy** » Tue May 15, 2012 7:41 am

I don't see much of a problem either. I've got a few Japanese power supplies that I use with a few of my game systems and they work perfectly fine. They might generate a little bit of extra heat but as long as they're well-ventilated thee should be OK.

kuroichi · Post by **kuroichi** » Tue May 15, 2012 8:48 am

Be careful, as running something on the wrong voltage can damage it over time, even one as small a difference as US to JPN...

Saying that however, check the voltage range on the back of the synth, as it may be capable of running on a broader range of voltages. Although with its age as a factor I doubt that.

Silverfish · Post by **Silverfish** » Tue May 15, 2012 9:28 am

Not to give bad advice or false hope, but I bought an akai sampler off a guy from Japan, and I was really nervous about ever using it without the correct adapters. However, after careful inspection of the internal power supply, I determined that it was fine. And indeed, it' runs fine. Maybe check inside.

Danchenka · Post by **Danchenka** » Wed May 16, 2012 3:53 am

I took a quick look at the service manual for the poly 61, and it appears that they shipped with two different transformers: One for 220V and 240V use, and another for 100V and 120V use. So you have the right transformer for your region. However, the transformer can be configured for either 100V or 120V use. As others have pointed out, the difference is small enough that you can probably get away with using it as is, but if you want it to run exactly as Korg designed it to run, you'll need to make a small change to the wiring of the transformer. It should be quick and easy for anyone comfortable working with power supplies, but don't mess with it unless you know exactly what you're doing. Get a tech, or a knowledgeable friend, to do it for you. Otherwise you risk damaging the synth, or worse, electrocution.

synthparts · Post by **synthparts** » Wed May 16, 2012 4:41 am

Running a 100V synth at 120V will shorten the life of the rectifiers and voltage regulators and will cause more heat inside the synth. 100-120V adapters are cheap.

Aaron2 · Post by **Aaron2** » Wed May 16, 2012 8:44 am

Thanks for the responses, everybody.

Aaron2 · Post by **Aaron2** » Wed May 16, 2012 9:05 am

Danchenka wrote:I took a quick look at the service manual for the poly 61, and it appears that they shipped with two different transformers: One for 220V and 240V use, and another for 100V and 120V use. So you have the right transformer for your region. However, the transformer can be configured for either 100V or 120V use. As others have pointed out, the difference is small enough that you can probably get away with using it as is, but if you want it to run exactly as Korg designed it to run, you'll need to make a small change to the wiring of the transformer. It should be quick and easy for anyone comfortable working with power supplies, but don't mess with it unless you know exactly what you're doing. Get a tech, or a knowledgeable friend, to do it for you. Otherwise you risk damaging the synth, or worse, electrocution.

I'm quite handy the soldering iron, but I've never done reconfigured the transformer. Do you happen to know how this done? Can you briefly walk me through it?

DesolationBlvd · Post by **DesolationBlvd** » Wed May 16, 2012 1:04 pm

My Alpha Juno says it's for 100V - I've been running it mostly fine. But, I had an overheating scare - the display went out and the sound went all screwy. That was after a full day of it being on, though, and it turned on fine the day after. I'm planning on getting the converter to be safe.

Danchenka · Post by **Danchenka** » Thu May 17, 2012 5:44 am

Aaron2 wrote: I'm quite handy the soldering iron, but I've never done reconfigured the transformer. Do you happen to know how this done? Can you briefly walk me through it?

You'd be dealing with the mains voltage (I.E. 120 volts), and it's not something that I'd recommend doing with nothing more than a few guidelines from a random stranger on the internet. I am, after all, just a hobbyist. I've never opened up this particular synth, so I wouldn't know in too much detail anyway. I just looked at the service manual.

By the way, you can download the service manual here: fa.utfs.org/diy/korgpoly61/Korg_Poly-61_ServiceManual.pdf
The power supply is on page 10.

I still strongly suggest you get someone to help you. But having said that...

I've only done this once myself. In the case of my Kurzweil K2500, it was just a matter of unplugging a connector from one socket and plugging it into another. I doubt a Korg would be the same. If you open it up and take a look at the transformer, it's probably pretty obvious though. Hopefully, the transformer is labeled. If you see a connector labeled 120V with no wire connected to it, and you see a connector labeled 100V with a wire connected to it, you need to change the connection of that wire to the 120V connector. Obviously, do this with the synth unplugged. That's really all I can say.

Aaron2 · Post by **Aaron2** » Thu May 17, 2012 6:56 pm

Danchenka wrote:You'd be dealing with the mains voltage (I.E. 120 volts), and it's not something that I'd recommend doing with nothing more than a few guidelines from a random stranger on the internet. I am, after all, just a hobbyist. I've never opened up this particular synth, so I wouldn't know in too much detail anyway. I just looked at the service manual.

Don't worry, I promise not to sue you if you give me the wrong information.

I've opened up tons of vintage electronics (mostly tube and transistor radios, but also home organs) and I'm not the least bit afraid of what's in there. If it can be fixed, I'll try it. As long as I'm observing basic safety pratices, what's the worst that can happen, right? If it's broken now, and still broken after I've tried to fix it, I haven't lost anything.

Danchenka wrote:I've only done this once myself. In the case of my Kurzweil K2500, it was just a matter of unplugging a connector from one socket and plugging it into another. I doubt a Korg would be the same. If you open it up and take a look at the transformer, it's probably pretty obvious though. Hopefully, the transformer is labeled. If you see a connector labeled 120V with no wire connected to it, and you see a connector labeled 100V with a wire connected to it, you need to change the connection of that wire to the 120V connector. Obviously, do this with the synth unplugged. That's really all I can say.

That was quite helpful, actually. I've looked at the service manual, and have examined the page on which the power supply is shown. And I couldn't tell from that diagram whether it's also tapped for 120V. It just wasn't obvious to me from the drawing. I may get one of my vintage-radio friends to look at the schematic and give me his opinion.

I do appreciate your help, though! Thanks!

Aaron

Using 100V Japanese-Made Synths in the U.S.

Using 100V Japanese-Made Synths in the U.S.

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