Stepdown - need help

Telgere

Bought a onkyo tx sr605 in the states.
Thought it would have a simple switch for 110-220v on the back like the eu models but it doesnt.
Power consumption is 6.5A so guessing ill need a 800W+ stepdown.

This is the best i could find - http://www.t2retail.co.uk/productDetail.asp?Product=2737054&Submit=Find+Product

Do i have any other options?, is this stepdown necessary?

Any help appreciated - Thanks.

robfitz

The EU site shows the EU version of the device as 230V 50Hz 630W, so I think the transformer you linked too should be enough?

Another option might be to contact the EU supplier and see if you can buy a replacement power supply and replace it yourself?

fishdog

Bought a onkyo tx sr605 in the states.

Sorry I dont know what this is.

Volts X current = Power in watts

So 800W would be ok.

The transformers that they use on building sites will step down 220 volts to 110 volts. They are available in 1000 watts. They are cheap and robust. This would do the job for you. Howevere some of them are not designed to be left on for hours on end.

There are other ones available that can be left on. Try Eurosales or Kellihers.

The frequency is the same here as in the states, so you are ok there.

themole

fishdog wrote:

The frequency is the same here as in the states, so you are ok there.

Actully its not. We use 50HZ the US uses 60HZ. But most devices are designed to handle both due to different parts of the world using one or the other.

themole

fishdog wrote:

The transformers that they use on building sites will step down 220 volts to 110 volts. They are available in 1000 watts. They are cheap and robust. This would do the job for you. Howevere some of them are not designed to be left on for hours on end.

They also do not provide very "clean" power and hence are not good for sensitive equipment. They also give out quiet a strong magnetic field which is also not good for lots of equipment.

fishdog

We use 50HZ the US uses 60HZ

In both cases this is only an average, so at times we would be at 60Hz and they would be at 50Hz.

They also do not provide very "clean" power and hence are not good for sensitive equipment

I saw nothing in the post from the OP to suggest that "clean" power was required. That is why I said:

Sorry I dont know what this is.

when the OP refered to the equipment being used.

Anyway, there is plenty of protection available that can sole this easily.


I use american 110V equipment in this fashion all the time (about 10 years), no problems so far!

They also give out quiet a strong magnetic field which is also not good for lots of equipment.

Naturally! This will be the case with any transformer. Solution: Simple, locate the transformer far enough away from the sensitive equipment.

Or shield the equipment or transformer.

It is inportant to note that by simply using a socket in your home you are usining sevral transformers between yourself and the generating station.

themole, what would you suggest??

DublinDilbert

fishdog wrote:

In both cases this is only an average, so at times we would be at 60Hz and they would be at 50Hz.

To be honest this is completely wrong, there is no way that our grid ( or any other grid ) will vary greatly from the nominal frequency by more than a fraction of a Hz.

Under load the frequency on the grid might fall slightly say 49.95Hz, but when the load reduces the esb will allow the frequency to increase slightly say 50.05Hz, they do this so any synchronous timer units will not lose / gain time over a 24 hour cycle. So they make sure the average over 24 hours is 50.000Hz...

Also our grid is connected to the northern grid, which in turn is connected to the English grid, there's no way any part of the grid would be very far off nominal as they are all synchronized... Also the generators are designed to produce max power at a certain RPM....

What about all the synchronous motors do these turn 15% faster when we are at 60Hz? synchronous timers?



Anyway getting back to the OP's question, about getting his device to work off 220V, i've done this many times, although never with anything as powerfull/big as an audio power amplifier....

What i normally do is open up the device and re-configure / change the main transformer.... on many low power devices you can select different windings on the main transformer for 220V/110V operation by adding / removing links...

With a power audio amplifier it will be a bit different, they usually use a toroidal coil transformer, you'll have to see how many windings ect are on the one in your unit.. The transformer is typically used to produce 60V AC which is then rectified into a +/- DC supply which the power amplifier H bridge drivers use.... to go down this route you'll need someone who is quite handy, can take a few measurements and pick / fit a suitable transformer...

I'd probably look at using something like this:-

RS Stock No. 223-8285
http://www.radionics.ie/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=AND(avl%3aie,searchDiscon_ie%3aN)&Ntx=mode%20matchpartial&N=4294953553&in_dim_search=1&name=SiteStandard&forwardingPage=line&R=2238285&callingPage=/jsp/search/search.jsp&BV_SessionID=@@@@0123933243.1185368843@@@@&BV_EngineID=cccgaddlhmlggjgcefeceeldgondhgi.0&cacheID=ienetscape

Michael Collins

DublinDilbert wrote:

To be honest this is completely wrong, there is no way that our grid ( or any other grid ) will vary greatly from the nominal frequency by more than a fraction of a Hz.

Correct. A change of any more than around +/- 2 Hz would indicated a major blackout about to occur.

fishdog

DublinDilbert you link does not work so I dont know what you are suggesting.
I think you are making this more complicated than it is. We know that at 110V6.5 amps are consumed. This equates to 715 watts. Therefore an 800 VA 220/110 transformer will sole the problem. Cheap, reliable and simple.

Correct. A change of any more than around +/- 2 Hz would indicated a major blackout about to occur.

Not relevent, but I must admit you may be correct.

DublinDilbert

fishdog wrote:

DublinDilbert you link does not work so I dont know what you are suggesting.
I think you are making this more complicated than it is. We know that at 110V6.5 amps are consumed. This equates to 715 watts. Therefore an 800 VA 220/110 transformer will sole the problem. Cheap, reliable and simple.




Not relevent, but I must admit you may be correct.

I guess i was just trying to offer an alternative, as I've brought back quite a bit of stuff from canada over the past few years.... My link was to a Toroidal coil transformer in RS...

An 800VA transformer will work, but it's going to be very big.... its also going to consume aprox 80W just sitting there in stand by ( to magnatise the core), even if the amp is not turned on...

fishdog

When the amp is off the transformer will consume almost nothing. The secondary coil with be open circuit therefore the primary coil will have massive impedence hence low current hence low power consumption. The primary side of the transfromer is just like a large inductor when no current is drawn from the secondary side of the transformer.

If you do not agree with that you could just switch the transformer off! Then power consumption is zero!

themole

fishdog wrote:

Naturally! This will be the case with any transformer. Solution: Simple, locate the transformer far enough away from the sensitive equipment.

What i was saying is that the transformers used for power tools are possibly the worst kind of transformer in terms of magnetic field and quality of electricity that its possible to buy. They are designed for durability and high load, and i wouldn't running anything other than power tools off one.

fishdog wrote:

Or shield the equipment or transformer.

It is inportant to note that by simply using a socket in your home you are usining sevral transformers between yourself and the generating station.

Yes, but your are not running any equipment beside these transformers.

fishdog wrote:

themole, what would you suggest??

The best solution is to replace the transformer in the device or failing that buy a proper external transformer desigend for indoor semicontinuous use.

fishdog

Yes, but your are not running any equipment beside these transformers

I am not trying to be smart but I dont understand what you are trying to say.

What i was saying is that the transformers used for power tools are possibly the worst kind of transformer in terms of magnetic field

No magnetic field = No transformer

A magnetic field is required for a transformer to function.

If a magnetic field close to the equipment is a concern simply have the transformer far away from any sensetive equipment.

The best solution is to replace the transformer in the device

Big mistake, warranty gone!!! Also this is alot of hassle and has no real advantages. The new transformer has to physically fit, be of the correct type and have enough air circulation.

or failing that buy a proper external transformer desigend for indoor semicontinuous use.

= a site transformer!

What is it you expect to find inside a "proper external transformer" other than a coil or two of wire and an iorn core? There are not much to them, just size it correctly.

Bought a onkyo tx sr605 in the states.

This is designed to be pluged into the wall in the US without any "special" transformers being used, just normal ones from the electricity company. There is nothing special in a transformer, a site one is similar to a non site one!

themole, I think you are "over engineering" the problem.

themole

fishdog wrote:

I am not trying to be smart but I dont understand what you are trying to say.

You mentioned that the power has gone through many transformers before and what i was saying is that the field coming out of these transformers cannot affect the equipment in your house as they are not close to any equipment in your house.

fishdog wrote:

Big mistake, warranty gone!!! Also this is alot of hassle and has no real advantages. The new transformer has to physically fit, be of the correct type and have enough air circulation.

Even if the warranty is valid in ireland, which i very much doubt, it would be near to impossible to find somewhere to repair it. I once tried to get a US toshiba pda repaired in europe and they basically said i would have to send it to the us because they had no way of getting the parts here.

I looked into doing exactly what the op is trying to do and gave up because propper regulation costs too much and big transformers look ugly and produce strong fields.