Stepdown transformer for a turntable?

davidro

Lunatic Member
G'day all

I'm getting a turntable shipped from Japan to here in Sydney.

If it does arrive in one piece (fingers crossed) I will need a stepdown transformer 240v to 100v. The deck uses 5w only.

Would it be wise to get a proper and expensive Aussie product or would a cheap Chinese product (note: strictly it's a 220V to 100V) do the job?

I could go even cheaper and try something that does 240v to 110-120v as there are many available in this range. Would it affect a 100v turntable?

Whilst I understand power supply is important for a turntable, I'm trying to cut the cost as much as possible as I've spent too much on shipping already.

Any advices would be appreciated.
 
On this one I gotta say go with the quality AND for the proper voltage. About 2x the price, yeah, but you get the warranty and probable dependability versus ebay you bought it you own it. As an anecdotal aside, I have a Chinese manufactured wall wart powering our Cambridge 640P preamp -- another member measured the output on his (which by the way is the one all these units are shipped with) and it was putting out 14volts where it was supposed to be putting out 12. Makes me wonder what mine is really putting out.

Regarding the proper voltage? There's no telling how the table will handle 110-20V. It might run fine and it might not. If it doesn't and cooks something? :tears:
 
I'm getting a turntable shipped from Japan to here in Sydney.

Which TT is that? Is it a belt driven machine with synchronous motor? I'm asking because of the line frequency , which is an important parameter when dealing with overseas TTs.

PS: from http://en.wikipedia.org/wiki/Mains_power_around_the_world I learned that in Japan there is no uniform line frequency, it could be 50 or 60 Hz! What a nightmare for synchronous motors!
 
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Which TT is that? Is it a belt driven machine with synchronous motor? I'm asking because of the line frequency , which is an important parameter when dealing with overseas TTs.

PS: from http://en.wikipedia.org/wiki/Mains_power_around_the_world I learned that in Japan there is no uniform line frequency, it could be 50 or 60 Hz! What a nightmare for synchronous motors!

guiller it's a Yamaha GT 750. Direct-Drive. Would it affect this!? :tears:
 
guiller it's a Yamaha GT 750. Direct-Drive. Would it affect this!? :tears:

Most DD TTs use DC motors (as opposed to AC synchronous ones), so I would say it should be OK. I'll try to find the manual to verify this but I think you should be fine!
 
Most DD TTs use DC motors (as opposed to AC synchronous ones), so I would say it should be OK. I'll try to find the manual to verify this but I think you should be fine!

It does use DC motors! Thank God :sigh:
 
On this one I gotta say go with the quality AND for the proper voltage. About 2x the price, yeah, but you get the warranty and probable dependability versus ebay you bought it you own it. As an anecdotal aside, I have a Chinese manufactured wall wart powering our Cambridge 640P preamp -- another member measured the output on his (which by the way is the one all these units are shipped with) and it was putting out 14volts where it was supposed to be putting out 12. Makes me wonder what mine is really putting out.

Regarding the proper voltage? There's no telling how the table will handle 110-20V. It might run fine and it might not. If it doesn't and cooks something? :tears:

This is a hard one. I've spent more on shipping than the actual unit already!
 
Regarding the original question, this being a DC TT, the AC line voltage is downloaded, rectified and filtered at the power source of your TT, which should be of excellent quality considering the great TT you bought. I would say you could try the cheap Chinese transformer (check out the output voltage with a tester first). Just make sure it doesn't get very hot when plugged in for long time periods.
 
If you were using it with a vintage multi-voltage amp/reciever you could, "borrow" the voltage off the mains trafo's 100V tap. It wouldn't notice 5W draw and the modification wouldn't be difficult for a tech.
 
Another option would be to replace the internal transformer with a suitable 240 V type...

Greetings from Munich!

Manfred / lini
 
For what it is worth, the money in a set down (or stepup) xfrmr is in the wattage it can deliver. A typical turntable requires only a few watts of power to operate so I would not be overly concerned about the quality of a step down xfrmr.

You may also find that the table has a dual voltage capacity - it is quite common for Direct Drive tables of a certain quality to have this feature since, as mentioned, there need be no reliance on mains frequency

As Manfred points out a swap of the existing 220/240v xfrmr to a 110/120 version is also easy - just get a version that has a secondary that provides the same AC output as the current one and you are set. Sometimes am allowance needs to be made for fuses when you move to lower voltage as current draw may be increased as a result.
 
As an anecdotal aside, I have a Chinese manufactured wall wart powering our Cambridge 640P preamp -- another member measured the output on his (which by the way is the one all these units are shipped with) and it was putting out 14volts where it was supposed to be putting out 12. Makes me wonder what mine is really putting out.

If your friend measured it without any load this isn't uncommon. If the PSU is not a regulated type it will rely on the load applied to it to bring the voltage down to the required level.
 
If your friend measured it without any load this isn't uncommon. If the PSU is not a regulated type it will rely on the load applied to it to bring the voltage down to the required level.

Yup, and even worse, the more overpowered (i.e. above the actually required power rating) the replacement is, the higher that excess idle voltage may be. Hence I usually rather recommend to use a regulated model for replacing unregulated wall-warts, if the replacement is significantly more powerful than the original...

Greetings from Munich!

Manfred / lini
 
If your friend measured it without any load this isn't uncommon. If the PSU is not a regulated type it will rely on the load applied to it to bring the voltage down to the required level.

Yup, and even worse, the more overpowered (i.e. above the actually required power rating) the replacement is, the higher that excess idle voltage may be. Hence I usually rather recommend to use a regulated model for replacing unregulated wall-warts, if the replacement is significantly more powerful than the original...

Greetings from Munich!

Manfred / lini

Thanks gentlemen, for the advice. I will keep that in mind when looking for a replacement. Just to be clear for myself -- if I were to replace this 12/500MA with a 12/2A then it needs to be a regulated model in order for the idle voltage not to be too excessive? I now understand what is meant by 'regulated', finally, as well. It help ensure that the specified voltage being output is correct?
 
I've just noticed that my comment above isn't really worded all too well and hence might be misunderstood. In fact, lower wattage transformers rather tend to have a higher idle voltage than higher wattage ones - i.e. ratio of V(idle) to V(load) typically will be a good bit higher for the smaller tranny (provided both are otherwise the same type, 'cause that also influences that ratio). But the voltage will drop more quickly for the same load with the smaller one - so with a significantly beefier transformer it can happen that the load is too insignificant for the idle voltage to drop down low enough not to cause damage.

4dr: Well, yes, for devices that are originally powered with an unregulated DC wall-wart, I'd generally recommend that - 'cause with the regulated higher wattage replacement you can be sure that there simply is no excess voltage. So that's the safe way to provide a higher current capability in such cases - whether that's necessary at all would be another question, though... ;) But, of course, using a regulated power supply can just as well be a waste, depending on the circuitry of the device. E.g. on quite a few devices there will be an internal regulation instead anyway, so knowing the actual circuitry (e.g. by checking the service manual) usually is pretty helpful for choosing the most suitable replacement power supply...

Greetings from Munich!

Manfred / lini
 
This is kinda getting too complex for me and I wonder if the gents can kindly let me know if it's alright to buy a HK-born cheapo transformer for my uses?

I don't think I can replace the internal power supply :(
 
i bought one on ebay for around $60 several months ago and it's been working fine for my RCM which i bought from america.
 
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