Japan - UK step down confusion

[Bugle]

Hello there,

I've just been gifted a Yamaha QX3. I can see it's Japanese and that I'll need a converter but I'm worried I'll get the wrong one and damage the sequencer. Any wise heads here confident of pointing me at the best item to purchase?

Cheers

[ajay_m]

You will need a step down transformer to convert our 230v mains voltage down. The Japanese use an unusually low 100v mains but any reputable manufacturer builds in significant margins to power supplies so providing the standard US 110v will be fine. UK to US power convertors are widely available. Just don't try using a plain adaptor plug that doesn't have a transformer.

[Kwackman]

SOME pictures of the QX3 show it with a DC input jack, for an external power unit, but the manual shows a mains cable directly connected (no socket), and a review mentions a power connector!
So, what's on the back of your QX3?

[Hugh Robjohns]

Personally, I'd use a transformer designed specifically to generate 100V for Japanese equipment, rather than 110 or more for US gear, just to minimise the stress on vintage power supply components.

And check that whatever transformer you choose has a sufficient wattage (VA) rating for the equipment you're planning to power from it.

And the correct socket for the Japanese plug!

This company claims to specialise in 110V converters...

https://airlinktransformers.com/categor ... converters

This 50W model costs £40, for example.

https://airlinktransformers.com/product ... -uk-ja0050

Or this 100W model for £70

https://airlinktransformers.com/product ... -uk-ja0100

[Bugle]

Thanks for the replies.

It's a lead out the back attached to a two-prong.

The back reads 6.5w 100v 50/60hz

I can't see anything about DC or AC

I just checked out that website but it's asking me to specify milli amps. I've no idea what to put there. Tbh, I'm just a musician who plugs stuff in and plays them and knows next to nothing about what's whizzing around in these magical boxes. Ask me to sightread some Liszt and I'm there. Ask me to patch a modular and I'd probably blow it up!

[Hugh Robjohns]

The back reads 6.5w 100v 50/60hz

I can't see anything about DC or AC

The fact that it states a frequency defines it as AC.

I just checked out that website but it's asking me to specify milli amps.

Odd! It just asked me for input and output voltages, and a power rating...

But since Watts = Volts x Amps, and you know the unit consumes 6.5 W and operates on 100V, the current draw is 6.5/100 = 0.065A or 65mA.

...but since its necessary to have a higher power rating in the converter than the load, and a 50W model is the smallest they offer, I'd go for that.

[ef37a]

Can I repeat Hugh's warning about a 110V transformer? Remember, our mains voltage is rarely the nominal 230V, mostly over 240. I get a very consistent 245V.
Then the fact that 50W is the lowest power transformer available it will barley be loaded at all at 6.5W and so deliver its maximum voltage. Traff voltages are usually quoted at rated load and volts will rise for a lower current draw.

The amp company I was with went to the trouble to have specially wound 100V transformers for the Japanese market. Most firms it seems just ship a US model?

(as for S America? Don't ask!)

Dave.

[Hugh Robjohns]

I get a very consistent 245V.

I'd complain to your local mains distribution company (not your utility bill provider) and ask them to change the tap on your local substation.

PW did that a few years back (his was close to 250V most of the time) and they were happy to help.

At 245 you are technically within spec (216-253V or -6 to +10%), but it's definitely on the high side and we are supposed to be trending to 230V.

My supply has consistently been 230 +/- 1V for the 25 years I've lived here.

For anyone interested to know what their mains voltage is, there are various plug in testers at little cost.

Eg: This one for £10 https://amzn.eu/d/2Wgl5De



Shows mains voltage and frequency, and if you plug a device in the front it will show the current and power consumption, as well as the cost of running it.

[ajay_m]

While I doubt that 110V is likely to be an issue, it is true on reflection that we are dealing with fairly elderly gear. Perhaps best to be safe, especially given the very low loading on a likely transformer. Not long ago I came across an old DX7 where the capacitor across the mains primary had failed; in this case creating a scary little smoke cloud although it didn't actually catch fire.

Just be sure to purchase from a reputable company. ebay and especially Amazon are not safe places to purchase power supplies of any kind, I strongly recommend under no circumstances dealing with either for safety critical gear.

[ef37a]

I get a very consistent 245V.

I'd complain to your local mains distribution company (not your utility bill provider) and ask them to change the tap on your local substation.

PW did that a few years back (his was close to 250V most of the time) and they were happy to help.

At 245 you are technically within spec (216-253V or -6 to +10%), but it's definitely on the high side and we are supposed to be trending to 230V.

My supply has consistently been 230 +/- 1V for the 25 years I've lived here.

For anyone interested to know what their mains voltage is, there are various plug in testers at little cost.

Eg: This one for £10 https://amzn.eu/d/2Wgl5De



Shows mains voltage and frequency, and if you plug a device in the front it will show the current and power consumption, as well as the cost of running it.

Oh, it's been that way for over 50 years Hugh, don't think shall bother thanks.
A few years ago I moved into a workshop (Kingsheath Npton) and if you switched more than one 500va variac on the breaker would trip. Turned out we had 254 volts! Did get that sorted.
All the amps were run at a measured 230V for specc' testing.

Dave.

[ajay_m]

Oh yeah. That reminds me. Years and years ago I had an old Teac A3340 reel to reel deck and picked up the companion little four track mixer they made to go with the recorder. It worked fine but then I looked on the back and the label said '100V AC'. Hmm, I thought. What's in there?. Turned out someone had put a whopping big 10W wirewound resistor in series with the mains primary which - more or less - dropped the voltage to something that luckily hadn't blown everything up. I got a proper 230V transformer with appropriate secondary voltage that fitted and just replaced the transformer, went back to the shop with the resistor in hand and got the money to cover the transformer, no arguments from them. (was second hand, they certainly didn't do the bodge job).

Now that 3340 was already vintage gear when I bought it. The capstan roller was getting a bit worn and one VU meter light had failed. I rang Teac's local office. Oh sure, they said, we'll order the parts from Japan for you. That'll be 20 bucks. And they did - for a machine that must have been a couple of decades old at the time. Those were the days!

[Bugle]

I really need to go back to school!

Cheers chaps. I'll go with the model you've recommended, Hugh.

[James Perrett]

Oh yeah. That reminds me. Years and years ago I had an old Teac A3340 reel to reel deck and picked up the companion little four track mixer they made to go with the recorder. It worked fine but then I looked on the back and the label said '100V AC'. Hmm, I thought. What's in there?. Turned out someone had put a whopping big 10W wirewound resistor in series with the mains primary which - more or less - dropped the voltage to something that luckily hadn't blown everything up. I got a proper 230V transformer with appropriate secondary voltage that fitted and just replaced the transformer, went back to the shop with the resistor in hand and got the money to cover the transformer, no arguments from them. (was second hand, they certainly didn't do the bodge job).

That reminds me of a Dbx 117 hifi compressor/expander that I have. I'm fairly sure that, when it first arrived here, there was a capacitive dropper in front of a 110V mains transformer. I think it had been like this from new. The capacitor/transformer combination was soon replaced by a properly rated transformer.

[nathanscribe]

Checking the QX3 service manual, it looks like Yamaha used the same PSU board for the Japanese and US markets, but employed selected different component values for each. In this case I'd second the recommendation for the correct UK-Japan stepdown.