I have been having a problem with my computer speakers. They, for
no apparent reason, start buzzing very loudly. I've determined
that, if the speakers are powered with a slightly high power line
voltage, they will indeed buzz. I tested this by plugging the wall
wart into a Variac and monitoring the voltage with a DMM, not true
RMS, actually a Fluke 8020A.. At about 126 volts, the buzzing
starts. Today I came into the house and noticed beeping from my
computer's UPS. It was definitely in the "power out of range, use
the batteries" mode. The inverter was humming and there was some
heat coming from the heat vents on the UPS. After checking around I
measured the line voltage at 127 volts. I thought this was a bit
high so I called the power company. They indicated that this was
NOT considered high, but are sending out a tech anyway. So, my
question to all you experts out there, what is considered high? My
UPS thinks it's high. My speakers don't work, but, I know they are
cheapies.