Yamaha RX-V371

Thread Starter

Ballistic

Joined May 10, 2015
16
naa, gonna get a 220 to 18 volt transformer at work tomorrow and then fit it. That should gimme about 9 volts output @ 110v to switch on the relay.
 

R!f@@

Joined Apr 2, 2009
9,918
What about your main power transformer ?
The one that powers the Amplifier that actually produces sound.
The stby Tx is used as the name suggests. It powers the u-com only. Not the whole Amp.
The Power transformer is also 110V if there is no 220V setting.

You put a 220V stby Tx, it will work for stand by and power on..no problem.
But as soon as the relay switches on, the 220V will fry the 110V power transformer.

I am wondering why no body suggested this...!
 

Thread Starter

Ballistic

Joined May 10, 2015
16
Gonna see if I can get a step down convertor at work tomorrow and check it out.
quote I made from post 9

Gonna get a 500w 220-110v convertor tomorrow, it should be enough to power the unit, in the meantime that is.
 

ian field

Joined Oct 27, 2012
6,536
quote I made from post 9

Gonna get a 500w 220-110v convertor tomorrow, it should be enough to power the unit, in the meantime that is.
If it was something lower powered - RS components (and probably various others) used to sell mains transformers with 2x 110V primaries, you wire them both in parallel for 110V or series for 220V.

Numerous times I've used them as autotransformers to run imported radios etc.

An old GE multiband radio in particular, it had PSB and UHF - I used one of those twin primary jobs as an autotransformer to run it up, then I was able to measure the secondary voltage and find something suitable with 220V primary.
 

ian field

Joined Oct 27, 2012
6,536
just a thought,if both transformers are 110v, then wire the primaries in series to test it.
They have to be identical primaries - or one will get more volts than the other.

Even if they *ARE* identical - if one has loaded secondaries and the other doesn't................................................
 

crutschow

Joined Mar 14, 2008
34,285
In general you can only place the primaries of identical transformers in series and that's only of the secondaries are also in series.
 

Thread Starter

Ballistic

Joined May 10, 2015
16
yeah, but using a 220v 9-0-9 at 110v via a step down convertor should get me to 9v, that should be enough to switch the 9v relay on the standby board.
 

R!f@@

Joined Apr 2, 2009
9,918
It's possible. Do check the power Tx for a parallel primary winding for 110V.
Series connecting them will make it a 220V one
 

ian field

Joined Oct 27, 2012
6,536
In general you can only place the primaries of identical transformers in series and that's only of the secondaries are also in series.
You want the 110V primaries in series, and the identical secondaries in parallel - otherwise, any current draw will exacerbate any imbalance between the two.
 

Thread Starter

Ballistic

Joined May 10, 2015
16
Got feedback from Yamaha today, they can get me the standby transformer for, wait for it! R45, that's just over $3. They were very helpful indeed.
 
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