Yamaha CS80

> 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.