I've moved from the UK and brought my Yamaha Receiver with me. I have this plugged into a step down transformer and have no problems. However, I now want to use the switched outlet on the rear to connect a 12 v trigger to share CD jukebox with a Niles multiroom receiver. Can anybody see any problems with this, given that the Yamaha is a Euro model and therefore "officially" runs on 220 volts?

The amps that I have looked inside of (many, many, but not yours) bridge in the incoming mains line to both the power supply transformer and the switched outlets in parallel. If you feed it 120v going in, it should send the same back out. Check it with a multimeter.

If you have a 220 VAC receiver...plugged into a 120 VAC outlet, then you are running it through a STEP UP transformer. Your receiver is then getting 220 VAC from the transformer, and outputting 220 VAC at the rear outlets. More info about your system would be helpful, especially how it's hooked up, plug configurations too. Since those crazy Europeans can't agree on one type of plug.

If this is the case, here's a quick fix; Get a voltage adator from radioshack. It's designed for people from the US to use 120 VAC appliances plugged into 220 VAC european outlets.

Unless I misunderstood your system, that is. If on the other hand, you have switched the internal power supply to run on 120 VAC, which is entirely possible, it then should be outputting 120 VAC, all you need to do is change the plug configuration.

ItsColdInMN is exactly right. I guess I should stick to working on US products in the US only, eh?

Thanks for the info and yes it is a step up transformer (D'oh!). As for the configuration (I think this is what you mean): The step up transformer (3 pronged north American standard) is plugged into a 120 standard wallsocket. The amp (Yamaha 795aRDS)is plugged into the step up transformer via a 3 prong-crazy-English-style-plug. The amp does not have a current switch on the back (English models don't, Euro models do) but has one of the 2 prong switched outlets.

Based on your response, if this is the case I would plug the Radio Shack adaptor into the switched outlet and plug the 12 volt trigger supply into the Radio Shack adaptor, thereby creating a crazy-English-style-plug-confirguration-in-North-America. Correct?

John

Be careful of which adapter you use to step 220 down to 110 for the 12v trigger. There are units rated less than 50 watts and units rated less than 1500 watts. Using a wallwart that draws only a few watts with the less than 1500 watts unit can blow up the wallwart. It has something to do with higher watt unit requiring a larger load in order to work properly.

Actually, Phil, the low wattage type uses a real two-winding transformer, and the high-wattage type uses a single high-current diode (rectifier) that changes the normal, full-wave sine wave into a half-wave 'half-a-sine wave' that puts out 220V, but as a half wave, the normal heater-element type of appliance "averages out" the wave form to be 110V over time. This is also how a dimmer works, by supplying line voltage at a smaller 'duty'cycle', or a percentage of time.

Larry
www.fineelectricco.com

Larry,
Bravo! You impress me once more!
Question, do you believe in low voltage lighting or incandesant?

Explain your question, please. As written, you're asking if I believe they exist, which I'm sure is not what you meant. Are you asking if I have a peference betwixt the two? If that's the case, I'd have to say that I have a small bias towards the line-voltage incandescents, because they're simpler to wire, cheaper and quieter (electrically speaking).

IMPORTANT NOTE to John!!

With a 220V supply feeding the receiver, remember that the switched (and unswitched) outlets will be supplying 220V! You'll need either a 220V-to-12V wall-wart or the aforementioned transformer-type "voltage converter". Treat the switched receptacles as if you were still in the UK.

Note to everyone else: Remember that, in the UK, one end of the 220V line is grounded, which means that there is a potential (difference) of 220V between the hot wire and earth, such as cable coax shields, the chassis of 3-prong-plug-equipped components, etc. Ever see the insulation colors in a European power cable? Blue - sky (hot) and brown - ground (earth).

In the US, while there is a potential of 220V between lines (or 'phases', for X-10 users), there is only 110V from any hot wire to earth (neutral and ground). This is done as a safety measure.

Even if there is ever a flashover or unintentional connection between a utility transformer primary (15KV or more), the voltage-to-earth of the wires in the home will be forced to remain at a relatively low voltage, except maybe for the few miliseconds that it takes for the fault-current device(s) to operate.

Larry
www.fineelectricco.com