This is a head scratcher. 
Why would a circuit like this be built? It might be to ensure that the so called "neutral" side is at earth potential, but why? Millions of amplifiers have built and sold safely without.
In almost all the mains I used in France, there was no neutral. Both wires were 110V above ground. IMO this is safer than 220V on one side. Sure you get 220V between the wires, but only 110 (to ground) if you touch one wire. The system was called Biphasé.
In a theater were I worked, we had the 4 wire biphasé system (2 sets of 2). Our new dimmer rack was meant for 3 phase, so the electric company installed a 4 wire to 3 wire transfomer. We then had 220V to ground, and it bit hard when you touched it!
Why would a circuit like this be built? It might be to ensure that the so called "neutral" side is at earth potential, but why? Millions of amplifiers have built and sold safely without.In almost all the mains I used in France, there was no neutral. Both wires were 110V above ground. IMO this is safer than 220V on one side. Sure you get 220V between the wires, but only 110 (to ground) if you touch one wire. The system was called Biphasé.
In a theater were I worked, we had the 4 wire biphasé system (2 sets of 2). Our new dimmer rack was meant for 3 phase, so the electric company installed a 4 wire to 3 wire transfomer. We then had 220V to ground, and it bit hard when you touched it!
Here is a photo. The model number is just listed as
In the mean time I've borrowed a transformer from a friend who immigrated from Europe and it puts out 0, 240V and the amp works great. Unfortunately, it is only 500W, not nearly enough to run the amp long term. So I've ordered a 5000W transformer of the same brand. Hopefully it will be wired like it's litle brother. Here is a photo of the inside of one the transformer I've been trying to figure out how to rewire. There are a total of 11 wires coming out of the windings. It will be hard to rewire without a schematic.
3000W ST Pro+ just like in the amazon listing. https://www.amazon.com/dp/B08DG6Y9F9?psc=1&ref=ppx_yo2_dt_b_product_details
It would be nice to get this one working since it has a nice grounded EU plug on the front.In the mean time I've borrowed a transformer from a friend who immigrated from Europe and it puts out 0, 240V and the amp works great. Unfortunately, it is only 500W, not nearly enough to run the amp long term. So I've ordered a 5000W transformer of the same brand. Hopefully it will be wired like it's litle brother. Here is a photo of the inside of one the transformer I've been trying to figure out how to rewire. There are a total of 11 wires coming out of the windings. It will be hard to rewire without a schematic.
Hi . If you have dmm ,try to measure output 240v outlet ,if any wire have contact to ground . Maybe secondary winding is just floating and you may ground any end of it. Also you may try just do some test ,put a small power lamp ,incadescent , not led , and connect it between output one of wires and ground , lamp must not lit . If lamp lit ,it means transformer output configured for 2x120v output and you need to locate center tap and disconnect it .
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I suggest to return the transformer, if you can. The picture at post #22 seems to show safety issues that aren't allowed by CE regulations. I guess that this product is also not UL listed. It is a poorly assembled product anyway. The Amazon listing for model number called "3000W" claims a 2000W load capability, but the toroid looks smaller than the required size. It may have a poor output regulation and it may also buzz at high load. I found out that cheap no-brand voltage transformers are usually a bad choice.
I had the opposite need lately. The voltage converter I initially bought from Amazon was as bad as the one on post #22. There is a properly built Hammond transformer on the market, but it is expensive and not suited for high power loads. I ended up building the converter myself. I bought:
Wiring is trivial and the transformer is safe and properly sized for the load. It costs twice as much as the China product and some effort was required, but it just works. It allows the use the good power cables I already had.
I had the opposite need lately. The voltage converter I initially bought from Amazon was as bad as the one on post #22. There is a properly built Hammond transformer on the market, but it is expensive and not suited for high power loads. I ended up building the converter myself. I bought:
- 1 UL-listed standard US wall plug (from AmazonGlobal) for the output. You may need a EU plug instead.
- 1 standard insulation toroidal transformer with dual 110V primary and secondary windings,
- 1 IEC panel mount socket with switch and fuse holder, for the input,
- 1 electrical box of suitable size (leave some space to facilitate heat dissipation, a rough estimate is 1% of the load plus a few W of idle power).
Wiring is trivial and the transformer is safe and properly sized for the load. It costs twice as much as the China product and some effort was required, but it just works. It allows the use the good power cables I already had.
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This is a issue I see often lately on imported products that have not been designed in EU. There may be a rudimentary triac-based solid state relay on the primary side of the power transformer, maybe to implement a power-on sequencing scheme. UK and some EU countries have a polarized plug with guaranteed phase/neutral contacts, but this is not a general EU requirement, as example Italy does not have a polarized plug and I had to do the "reverse the plug to get the device working" trick sometimes.This is a head scratcher.
What is it with the 11 wires...some internal circuitry along with the primary and secondary windings?
Better to replace the entire unit (power supply), but we have to see how the protection system is linked to the transformer, as the OP reports it is working fine with another type of step up transformer.
Better leave it alone, and get the bigger transformer from a well known supplier.
Little wonder such products are commercial failures.
Better to replace the entire unit (power supply), but we have to see how the protection system is linked to the transformer, as the OP reports it is working fine with another type of step up transformer.
Better leave it alone, and get the bigger transformer from a well known supplier.
Little wonder such products are commercial failures.
I would guess the complex wiring might have to do with switching the inputs so that it automatically makes 120 from 240 and 240 from 120, or something fancy.
This reminds me of the time a repair man known to me spent three days trying to fix horizontal rolling on a Trinitron built at the Sony Welsh plant, in Bangalore.
Luckily for him, I had visited the local British Library and seen the service bulletin, bad batch of Tantalum caps in the power supply.
When I told him, he looked at me as if his head was spinning, then partly out of regard for me, and partly because he was at his wits' end, he changed them, and... Voila!...
Sony TV were kind of infamous for this kind of fancy circuits, and flimsy power supplies.
Now regarded as branded junk here, LG and Samsung sell in multiples of Sony volumes here.
This amp may be having some extra functions powered from the transformer, and those may be sensing phase shifts.
Smart Alec design.
Luckily for him, I had visited the local British Library and seen the service bulletin, bad batch of Tantalum caps in the power supply.
When I told him, he looked at me as if his head was spinning, then partly out of regard for me, and partly because he was at his wits' end, he changed them, and... Voila!...
Sony TV were kind of infamous for this kind of fancy circuits, and flimsy power supplies.
Now regarded as branded junk here, LG and Samsung sell in multiples of Sony volumes here.
This amp may be having some extra functions powered from the transformer, and those may be sensing phase shifts.
Smart Alec design.
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That kind of "universal voltage converters" works both way, so they need extra bucking windings to compensate for the high losses due to the small core (a extra winding for each side), and they may also have a thermal fuse with external connections. If you don't already have a general idea of the way they are put togheter, figuring out how to do modification safely is not trivial.
Said that in Post #14...
The voltage converter in the picture may have extra safety features, as required by law maybe?
Without a schematic, see if you can return it.
Or keep it as a back burner project.
Once you can figure it out, go ahead.
The voltage converter in the picture may have extra safety features, as required by law maybe?
Without a schematic, see if you can return it.
Or keep it as a back burner project.
Once you can figure it out, go ahead.
I plan to return it. Contrary to the one post above, I see no safety issues that don't meet UL. However, it doesn't have a UL marking. It does have CE. I will put the wires back in their relatively neat arrangement and re-secure them with zip ties. I opened this one up to see if modification was easy. I think I'm past that now and going to put it back together.
Yes, it gets complicated because there are 220 in, 110in, 220out, 110 out. indicator lights, fuses, switches, etc. without a schematic, it would be a weekend project to figure it out.
https://www.voltage-converter-trans...vt-15000-15000-watts-step-up-down-transformer
this may be the one I end up with. Note that it says specifically that it doesn't do US type 220.
Jerry
Yes, it gets complicated because there are 220 in, 110in, 220out, 110 out. indicator lights, fuses, switches, etc. without a schematic, it would be a weekend project to figure it out.
https://www.voltage-converter-trans...vt-15000-15000-watts-step-up-down-transformer
this may be the one I end up with. Note that it says specifically that it doesn't do US type 220.
Jerry
Pano, not sure how special it is. I'm a problem solver, always have been, so I enjoy this. The expense isn't so much. Returning all the transfomers that don't do what they say they will to Amazon. The big one I linked is only $499. Compare that to a PS Audio power bock that is only 1500 watts and is currently on sale for $5000.
That said, I hope this amp turns out to be special. It currently sounds pretty bad played with inadequate power from a little 500W transformer. My 10wpc sophia kicks it's butt.
That said, I paid $3k for this amp used. New is is about $8k depending on the exchange rate. I thought the 220V transformers would be great since doubling the voltage halves the current so the wires look twice as big to the amp. I'm a big believer in big wires supplying amps. While most amps will work fine on US version of 220v, sadly this one won't. So my gambit didn't work out as well as I'd hoped.
Jerry
That said, I hope this amp turns out to be special. It currently sounds pretty bad played with inadequate power from a little 500W transformer. My 10wpc sophia kicks it's butt.
That said, I paid $3k for this amp used. New is is about $8k depending on the exchange rate. I thought the 220V transformers would be great since doubling the voltage halves the current so the wires look twice as big to the amp. I'm a big believer in big wires supplying amps. While most amps will work fine on US version of 220v, sadly this one won't. So my gambit didn't work out as well as I'd hoped.
Jerry
CE mark for some items is self certified, or can be done at a reasonable well known lab.
You have to have a responsible atttorney in the EU.
UL means tested at a UL facility, to their standards. Some of their labs are overloaded, take times for some tests, but better regarded as for testing quality.
That said, I would spend some effort on locating the amp schematics, and learn more about it for future issues, likely to happen in such a complex design.
You have to have a responsible atttorney in the EU.
UL means tested at a UL facility, to their standards. Some of their labs are overloaded, take times for some tests, but better regarded as for testing quality.
That said, I would spend some effort on locating the amp schematics, and learn more about it for future issues, likely to happen in such a complex design.
Thanks but in less than a week it will be back on a shelf at amazon where it will work fine for someone with a less picky load. --Jerry
Looks complex compared to Japanese sets.
What is worth $18,000 in it?
And I meant the amp schematics, not the transformer schematics.
This thing will have issues sooner or later.
Like British bikes, and the myths around them.
The Japanese bikes just worked, and the British had you cultivating special mechanics / magicians.
What is worth $18,000 in it?
And I meant the amp schematics, not the transformer schematics.
This thing will have issues sooner or later.
Like British bikes, and the myths around them.
The Japanese bikes just worked, and the British had you cultivating special mechanics / magicians.
As supposedly anyone here does, I'm scratching my head how this phase sensing utility in your amplifier works, and especially what it is good for.
I don't know where you live, so have to ask if it is possible to swap the converting autoformer's mains plug? If it isn't, I suppose that it is wired in a way that neutral connects to the CT and live to one of both ends. So one gets 120-0-120 Vac. What happens if you just swap both input leads, which would give 0-120-240 Vac?
Best regards!
I don't know where you live, so have to ask if it is possible to swap the converting autoformer's mains plug? If it isn't, I suppose that it is wired in a way that neutral connects to the CT and live to one of both ends. So one gets 120-0-120 Vac. What happens if you just swap both input leads, which would give 0-120-240 Vac?
Best regards!
Or maybe Chris has pointed out the easiest fix. Does the transformer have a 120V primary winding? Many do.