Re: Voltage Regulator and Buzzing Sounds!
Hmm, very strange indeed. The only thing that the A/C unit could possibly do is cause a voltage drop at the mains that means the regulator needs to take more amps to keep a load supplied with a steady 220Vac, but I would never think that this would be significant enough to cause any issue - the mains should be able to limit the load regulation well enough so that it's barely noticable, this isn't (or shouldn't be) a problem in any western nation, but if you are in Saudi Arabia, they might have issues - I don't know anything about the state of their electrical grid, only ever worked on supplying them a new transformer... for an airports own power station... I guess that says it all really, lol.
That being said, if the reason for the regulator is because of this very thing, then that could also make the regulator work harder and causing the problems.
Bottom line, these things are usually well built with pleanty of protection built in. It appears to be from a decent manufacurer, and Japanese at that. I wouldn't worry too much about it. If it fails, it fails, but I doubt very much that it will take any equipment out with it if you have them surge protected.
Sorry for getting your posts a bit mixed up - I'm usually reading them half asleep :S
Delta: "What's wrong Chris?? Chris: "I miss my old Cyrix"