In all the years I've been playing I have to say that I've never run into any voltage problems - pure luck, no doubt.

Anyway, here's something similar regarding Hz that happened a long time ago - you might get a chuckle out of this.

Like some of us here, we used to lug around a big old Hammond, which, in general, was pretty unsinkable. Being a UK model the tonewheel generator ran at 50Hz. So, come one fine Spring, we take off on an 8-month stint of U.S. Air Force bases around Europe and lo and behold, the first one we get to (Iraklion, Crete) has its own power supply at 60Hz.

So yikes, all of a sudden, the tonewheel generator is now running at a different speed with the consequence that I either had to re-learn all our songs in a new key, or play the resident acoustic piano for three months - guess which option won. "Green Onions" and "A Whiter Shade of Pale" didn't sound too convincing that summer!