Japanese Hi-Fi Voltage Question

#1

I have a Denon hi-fi from Japan that was my brother’s and he used it when he lived over there. I want to be able to give it to another family member and have it work. I have a step-down transformer that halves the British 240V output down to 120V to use American appliances. However, over in Japan they have a funny mix of voltages depending on which part of the country you are in. This particular hi-fi specifies that it is for 100V. Would I be safe to use my step-down transformer with output at 120V in this hi-fi, or is it likely to blow up?

#2

Someone else may have a better answer, but usually mains power is considered to have a 10% tolerance…

230V +10% = 253V
230V -10% = 207V

This is why across Europe the voltages vary due to legacy systems:

UK: 240V
Italy, Spain & Russia: 220V
Everywhere else: 230V

With a 10% threshold at 230V every country is included.

However in Japan using a 120V transformer for a 100V product (+10% = 110V) would be significantly out of tolerance, you could measure the real world voltage of the transformer to confirm it’s actual output, but personally I would suggest the answer is no.

However it’s unlikely to go bang, so much as run too hot and wear out prematurely.

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#3

In 1960, the supply voltage to domestic properties in the UK was nominally 240 V AC at 50 Hz, although the declared voltage in the UK is now 230V AC +10% to -6% done I believe at the same time the colours were harmonised

. … Since 1995 the nominal voltage across Europe has been 230V (400V 3 phase).

In practice nothing has been changed in the UK.

This was my understanding and has been confirmed online so @unknowndomain you are correct

Until recently I was a National Inspection Council for Electrical Installation and Contracting (NICEIC) registered electrician

I expect @andrew_d you will be fine

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#4

Wait for it…

I am a fully trained in portable appliance testing. Lol

This is where I learnt this.

#5

My own outlet supply voltage is currently 242V. It has been fairly consistent when I have tested it over the years. I will do a test with the transformer later on.

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