Moving - Power Supply Help Needed

[enomis]

Hello all,

In a month I will be moving from the USA to Norway music gear and all. The move may or may not be permanent but will definitely be fairly long term. I have been searching the archives with regards to switching gear over to 220V 50Hz and could use a little help sorting out a good solution. Luckily most of my gear can make the switch easily and there are just few synths that are not setup to switch over.

Searching the archives I have read a variety of responses to this question. Below are the response I have gleaned with my own comments and questions that I hope someone can respond to.

Option 1 is to have a local tech replace the internal power supplies with ones that work locally. Since the move may not be permanent I'd rather not go this route. Is there a way of replacing the internal power supply with a wall wart type external power supply?

Option 2 is using a step down transformer. My understanding of this is that a step down transformer takes care of the voltage difference but not the frequency difference (60hz vs 50hz in Europe/Scandinavia). Will the difference in frequency have a long term adverse affect on the synths?

Option 3 is using a rechargeable battery with an inverter that puts out 120V 60Hz. I have found some "online" UPS devices that do this but haven't found any that take 220V input and put out 120V. Theses devices also seem really bulky and expensive. If I understand the process correctly, it also seems rather convoluted to go from AC power to DC power back to AC power just to have the synths' internal power supplies convert back to DC. This seems like a non-starter but could use some clarification from someone with more knowledge.

The synths in question are:

- Roland JX3P - this synth was originally a European model but was modified to work in the USA by an earlier owner. I don't know how the conversion was done. Would it be possible to go to a wall wart external power supply?

- Yamaha DX11 and TX81Z - The backs of both synths say 120V 60hz however the manual I found online states that the US/Canadian version of the TX81Z is rated for 110-120V and 50/60hz. Would a step down transformer work and the frequency difference not be an issue?

- Korg MS10 - The MS-10 is rated at 120V and 50/60Hz. Here again, can I assume that I could getaway with just a step down transformer since it can handle both frequencies?

I have some instruments that have external (wall wart) power supplies. My understanding here is that I just have to find a wall wart that can handle the incoming current and matches the specs the unit is looking for (voltage, polarity, amperage). Is this correct?

I appreciate everyone's help on this.

[Mesmerised]

Most of the PSUs should be rather easy to modify. Mostly it's just a wire link on the board to select a different primary coil on the transformer.
A good idea would be to have the whole PSU replaced with a modern switching power supply, especially on the older synths. The switching supply doesn't care much about voltage or frequency so you wouldn't have to undo the changes after moving back.
AFAIK the Frequency difference 50/60 Hz shouldn't have any impact whatsoever, I wouldn't know why.

I wouldn't go down the route to use an inverter, the cheap ones especially put out very "dirty" approximate sine voltages and that might cause additional noise/hum in audio devices. Inverters with a "clean" sine wave are rather expensive.

So, try to modernize as many PSUs as possible, for the rest use a transformer.

[enomis]

Thanks for your response Mesmerised! This is a great help. I will look into replacing the PSUs with switching power supplies at the very least for the JX3P that has already been modified if not all four synths.

[Weirdofromouterspace]

Hi,

A good idea would be to have the whole PSU replaced with a modern switching power supply

I second that, absolutely.

AFAIK the Frequency difference 50/60 Hz shouldn't have any impact whatsoever, I wouldn't know why.

The AC frequency is filtered out anyway:
The transformer provides low-voltage AC, which is then processed by a rectifier. The resulting voltage looks like a sine curve with the parts below 0 V folded upwards. This unevenness is then flattened by a stabilizer such as the 78XX and 79XX integrated circuits. Remaining 50/60 Hz components are finally filtered (shortcut, actually) by a set of capacitors.

It doesn't matter whether it is an external PSU (I built quite a few of these in the above way for my guitar stompboxes) or an on-board PSU inside the device (synth, whatever).

[enomis]

Weirdfromouterspace thank your the more technical explanation on how the synths deal with the AC frequency. I'm limited in my knowledge of electronics but this makes sense. So the synths don't rely on the AC frequency for any of their functions?

Thanks again.

[Weirdofromouterspace]

Hi,

So the synths don't rely on the AC frequency for any of their functions?

at least I never heard of one that would . All these electronic circuits, be it a stompbox, a CD/DVD Player, an amplifier or a synth, to name just a few, use DC internally (portable units, including a few synths, can even run on batteries ). Small units (for instance stompboxes, portable CD Players,...) usually use an external PSU which is typically connected by a barrel plug, bigger ones internal PSUs. That also applies to synths: Two of mine (the Yamahas) use internal PSUs, the Minibrute has an external one with a barrel plug.

All the PSU is supposed to do is convert ugly, dirty AC polluted by frequencies and variation into clean, nice and constant DC. Everything else required is done by the circuits themselves.

[karmag]

Just wanted to add to the agreement that the 50/60 Hz difference shouldn't be a problem for most electronics, and if it says in the manual that something can run with either I wouldn't worry. A step-down transformer would be my choice for the Yamahas and the Korg. They shouldn't be hard to find in Norway - but you might want to bring a power strip.

Where the frequency can matter is when there is a motor involved, or with clocks.


I should also point out that you could just buy 230V gear when you get here, unless you're bringing something rare. Since you're going to be living in Norway, getting a TX81z off ebay would only cost as much as a couple of beers.

[enomis]

Thanks karmag and weirdfromouterspace.

My fears of destroying my equipment have been allayed!

I have read that when using a power strip with a step down transformer it is important to use a power strip WITHOUT surge protection. Can anyone confirm this?

Karmag, thanks for the tip on forgoing a couple beers for a TX81Z. Though TX81Zs are pretty easy to come by, I don't know how easy it would be to track down a DX11, JX3P or an MS10 in Norway without forgoing A LOT of beers

Instead of the Bigmac index it's the beer/TX81Z index

2 Norway beers = TX81Z
8 or 9 NYC beers = TX81Z

[karmag]

Not using surge protection seems like odd advice. Maybe that could refer to inverters? I suppose the output from those would look "square wave-y" enough that it could trigger something. But that's just speculation. A plain transformer should just put out what goes in, more or less.

And joking aside, I wouldn't know what the Norway market for gear is like. Not even sure where people would go to trade, but east of the border we have vend.se, which is pretty active. (I would say the TX81z index is quite reasonable too!)

[enomis]

There was a website that clearly described the dangers of running a surge protected power strip after a step down transformer. Unfortunately that site isn't currently accessible however I did find this as well:

http://www.audiokarma.org/forums/archiv ... 67453.html

Anyway, karmag, vend.se looks like a great site! Thanks for the tip. I haven't found a Norwegian equivalent yet. Some musical instruments pop up on finn.no (not specific to musical instruments) but not as wide of a selection as what I am seeing on vend.se.

[Mesmerised]

Yep, the info on http://www.gson.org/stepdown/ seems to be correct. I wasn't aware of these kind of step-down transformers. I'd never use something like this. Better invest in a transformer that has two separate coils and isolates the 110V part from the 230V part!

So, you really shouldn't be using surge protectors behind these kind of transformers. If you need surge protection you can put it on the 230V side.

[enomis]

Can anyone recommend a good company that makes step-down transformers? I've seen a bunch on line but digging through reviews they seem questionable. Thank you!

[808KickDrum]

For Roland, just about everything takes the PSB-120 (aka PSB 1-U). It takes 100 to 240 and 50-60hz.

I have used mine to power everything from a vintage SH-101 to brand-new VDrums.

Go for the real Roland version, no imitations. It's a great bit of kit -- so good I have three of them (thanks in part to a shipping error by an inadvertently generous online retailer).

http://www.guitarcenter.com/Roland-PSB- ... 1475592.gc