I recently imported from Japan a Super Famicom with a third-party SFC power supply by Hori. Everything does work, and I have no problem getting games to show on screen or to produce sounds.

However, after some delay, the Japanese power supply starts emitting a buzzing sound. We have it connected to a power bar to which other devices (including consoles) have been plugged in without previous issue.

Does anyone know if this is a normal occurrence due to the differences between Japanese and North American electrical systems, or if it's because we used a power bar instead of plugging the console directly into the wall outlet, or if it indicates an issue with the Hori power supply? Last thing I want is to fry my Super Famicom!