240V conversion for US Sony JA50ES

[Top Cap]

I acquired this Sony JA50ES some time ago from the USA and it runs from 240V via a step down transformer. Looking at the circuit of the PSU I see there are two mains transformers inside. Would it be possible to run this unit from 240V with the transformers wired in series? Something tells me this is only possible if each transformer has the same loading which clearly they do not but is it worth even a try? What does the team think.

[TrevorG3VLF]

I think it is impossible.
One transformer may have most of the voltage - POP.
Remember that it was designed for 60Hz so will be a bit marginal on 50Hz.

I have run two transformers in series but only with two similar secondaries in parallel to force the primaries to have the same voltage.

[mhennessy]

No chance!

[peterpiper]

Hi Top Cap, I tend to agree with Trevor but as the power consumption of a Minidisk is likely to be only 20 watts or less, a better way would be an autotransformer. almost any Tx with a split primary i.e. 2 windings of 120v could be used. 240v across both parts in series and 120v taken from one of the 120v windings.

Peter

[Maarten]

I think there is some misunderstanding because the full model number wasn't given. This is not an MDS-JAxxx but probably something like TA-JAxxxx or in any case an apparatus with a heavy audio amplifier on board.

The transformers cannot be put in series, as was said, since they aren't drawing the same amount of power.

A suitable step down transformer, as is currently used, would be the best solution.

[Goldie99]

Not that it changes the conclusions, but I think you'll find it's exactly an MDS-JA50ES mini-disc - the circuit posted by the OP looks to be a direct extract from the service manual at hifiengine. Power consumption is listed as 26W.

[mhennessy]

In fairness, the secondary-side fuses do look awfully large for a MD deck, and that could easily make one imagine that it's a power amplifier...

No chance!

Oh you pessimist! There is a a small chance that the two transformers have the same total load, a very small chance and not worth trying.

You could put them in series and use a small 230/115V transformer to make up the difference for the more power hungry transformer (or suck some power out of the smaller one). It may fit in the case making for a neat job.

I have done a 'quick Google' and it is indeed an MD deck with two same size transformers, so series may work after all.

[ms660]

Hertz permitting, stick to a stepdown/auto transformer, simples.

Lawrence.

[mhennessy]

Originally Posted by merlinmaxwell

I have done a 'quick Google' and it is indeed an MD deck with two same size transformers, so series may work after all.

You wouldn't say that if you'd looked at the full schematic in the service manual

You wouldn't say that if you'd looked at the full schematic in the service manual

I only looded at the pictures!

[Top Cap]

Thanks for your input chaps, I reckoned it was not possible but would have been nice to do, if it was possible, just to remove the in-line auto transformer I have. It is a low power device and does not have a power amp fitted, just built like a tank and one of the heaviest pieces of hi-fi separates I have ever handled. I am presently using a Cricklewood Auto transformer Item Number: TAE100, rated at 100VA.