Justin & Jerry's Hifi Blog

[jandl100]

Thanks Marco.

That was almost a useful post!

.... until a suitable step-down (bucking) transformer is used.

So where do I get me one of these, then?

The Yaqin is rated at 220V, as you know, and I'm feeding it 230V from a regenerator, so maybe not at so great a risk as from the 240-250V often encountered from the UK mains direct?

[MartinT]

My incoming mains is often at 250-252V but my P10 outputs exactly 240V. If your regenerator outputs 230V you are probably safe enough (all equipment must have some tolerance). However, do heed Marco's warning not to leave it switched on unattended.

[Marco]

Hi Jerry,

Thanks Marco. That was almost a useful post!

So where do I get me one of these, then?

Any of the good DIY guys here, such as Nick (lurcher), Ali Tait, Leo, Reid Malenfant, or even Anthony TD, would build you one. £100 should cover it. Basically, it steps down the UK voltage to 110V, which the amp was originally dsigned to used with.

The Yaqin is rated at 220V...

Trust me, it's BOLLOCKS, and simply a marketing exercise, designed to make them sell to UK buyers. The transformers may be rated for 220V, but the internal components, such as caps and resistors aren't, and so can't handle the over-voltage in the circuit for any length of time. That's what happened to my Yaqin.

One minute I was happily listening to music, and next minute there was a squealing noise... When I looked round the black capacitors in between the green-covered transformers were bulging out like someone's eyeballs, you see in horror films, and then the amp caught fire!!

Fortunately I was only a few feet away, so ran over and hit the off switch before anything more 'spectacular' happened, whilst gagging with the acrid stench of melted caps!

Luckily, Anthony managed to fix the amp, make it safe, and also perform a few tweaks, so the amp ended up sounding superb, but I can't stress enough:

THE YAQIN IS NOT SAFE FOR EXTENDED PERIODS OF USE, ON UK MAINS, WITHOUT A STEP-DOWN TRANSFORMER.

you know, and I'm feeding it 230V from a regenerator, so maybe not at so great a risk as from the 240-250V often encountered from the UK mains direct?

The 10V won't make much of a difference, as the circuit is still at danger from the effects of over-voltage, which it was never properly designed to handle!

Be very careful. I can only pass onto you the practical experience I've had using that amp - and others I know have experienced a similar thing.

Marco.

[jandl100]

Err - so you're saying it's really a 110V mains voltage amplifier?

That doesn't really make sense to me.

Surely the whole shebang would simply go phut as soon as it was plugged into 230V ...

Are there any electrically competent folks here who would care to comment?

[Ali Tait]

No, like a lot of Chinese stuff, the transformers are rated for 220v, which means on our mains components in the amp can be subject to over voltage. Given the poor quality of some of them, the result can be what happened to Marco. I have also had the mains transformer go on a Chinese amp. It did last several years though.

I'd be inclined to follow Maro's advice. Either change the mains trannie for a properly rated one, or use a bucking transformer to get the voltage down.

It's a lottery with the things. The amp could be fine for years, but why take the chance?

[jandl100]

No, like a lot of Chinese stuff, the transformers are rated for 220v, which means on our mains components in the amp can be subject to over voltage. Given the poor quality of some of them, the result can be what happened to Marco. I have also had the mains transformer go on a Chinese amp. It did last several years though.

I'd be inclined to follow Maro's advice. Either change the mains trannie for a properly rated one, or use a bucking transformer to get the voltage down.

It's a lottery with the things. The amp could be fine for years, but why take the chance?

Thanks Ali.

I'm up for paying someone to make up a bucking transformer widget that will take the voltage down to 220V.

Anyone?

[Ali Tait]

Bid on this Jerry. All you need to do is put an IEC on the output to plug into the amp. Set the voltage before you plug it in to the amp.

http://www.ebay.co.uk/itm/Zenith-6-A...item51a5f0923f

[jandl100]

Bid on this Jerry. All you need to do is put an IEC on the output to plug into the amp. Set the voltage before you plug it in to the amp.

http://www.ebay.co.uk/itm/Zenith-6-A...item51a5f0923f

Errr ... 0 to 100 on the dial.

How does that work then to set it to 220V ?

Yep, I really am technically incompetent!

[Ali Tait]

Ignore the numbers on the dial. Just use a multimeter to set 220v on the output by twiddling the dial, measured on the output lead. Then plug into the amp.

[jandl100]

Ignore the numbers on the dial. Just use a multimeter to set 220v on the output by twiddling the dial, measured on the output lead. Then plug into the amp.

Ummmm .... I'm not sure I feel safe meddling around with 100s of volts.

Yep, I've got a mutlimeter and I am quite happy sticking the probes into the holes provided on the Yaqin to check the bias - but fookin' around with bare wires at 200+V ....

Or am I being a wuss?