JH-i think we're moving backwards here.
you are talking about voltage overage.
i never ONCE suggested such.
i mentioned CURRENT overage.
why? because everything that you own that runs on electricity PERIOD is designed to NOT draw more current than the PSU that supplies its CURRENT.
house, car, synth-you name it.
whether something runs hot, cold, whatever is not a good way to gauge how well its working. for example, you cs80 runs somewhat warm to the touch. this is normal.
you should assess a PSU on how stable it holds its voltage and how much current is being drawn vs. how much CAN be drawn on it, not how hot it gets. voltmeter beats palm test every time.
and you definitely dont want to plug in your cs80 until you know exactly what it needs, and what you are about to give it.
"JH." <
jhaible@...> wrote: > TMK, i dont know of how a PSU that is rated for a higher current draw than
> it will need to supply could possibly damage a synth.
Damage would be the worst case - but I wasn't thinking about damage.
What I want is to run the synth at a mains voltage high enough for the DC
regulators to work properly, with some reserve for capacitor ageing - but
not much above that voltage. To keep the losses in the voltage regulators
and in the transformer iron low. I don't have experience with the 80, so I'm
eagerly listening to you and others who have worked on them, and I'm glad to
hear that things are not as complicated as I tend to make them.
>i would just buy a standalone unit that steps 240v down to 120v/110v, with
>an output that has at A MINIMUM 2X the wattage/amperage the >80 is rated
>for. preferably 3 to 4X.
I understood that you recommended this, but I'd love to understand ∗why∗ you
recommend to oversize it. Normally, a transformer gives its rated secondary
voltage at the rated current. To compensate for its copper losses, the turns
ratio is slighly bigger than calculated ideally, so the secondary voltage is
∗higher∗ than rated when the load draws only 1/2 or 1/4 of the rated
current. Of course, when the nominal secondary voltage is 110V, I might end
up at 117, and be just fine ... But then again, maybe not.
Thinking of it again, maybe the Yamaha synths aren't so sensitive about
mains voltage. My CS-50 and CS-60 don't hum, even though they are running at
230V instead of the 220V they were intended for. I'm probably oversensitive
because the bad experience with other brands. (My Prophet 5 used to hum like
mad with a slightly too high mains voltage and 50Hz.)
But heat is an issue, isn't it? One of the prevuious owners has put a fan
(!) on top of the mains transformer. (With a switch to turn it off,
fortunetely.)
I'll probably buy a ready-made stepdown box and return it if there's too
much hum or heat.
Thanks again for all the good advice.
JH.
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