I've got a couple of components around that have a hum problem, not through the outputs, but from the case.
One manufacturer suggested that I measure our home's AC voltage, and that turned out to be 124.5 to 125 VAC (confirmed by our local utility, whose residential spec is 120 VAC +/- 5%.) The manufacturer's response was that the unit was designed for 115 VAC, so that high supply voltage was the problem. (A friend at the utility suggested that one way to push more power over an aging infrastructure was to increase the voltage spec and thus provide the power increase at the existing current level--not that his firm would do that, of course, but I didn't hear any of that from him
.)
Someone suggested buying a variac to see if decreasing the supply voltage fixed the problem, but I never wanted to spend the money for one, though now with another component evidencing the same problem, maybe I should....but that would only possibly diagnose the problem, not solve it!
OTOH, the problem could be due to DC offset in the AC supply, correct?
Is there any easy/safe way to measure that in a home with not much more than a typical DMM? Or is the likelihood of DC offset on our AC circuits in a home not very high?
Thanks!
One manufacturer suggested that I measure our home's AC voltage, and that turned out to be 124.5 to 125 VAC (confirmed by our local utility, whose residential spec is 120 VAC +/- 5%.) The manufacturer's response was that the unit was designed for 115 VAC, so that high supply voltage was the problem. (A friend at the utility suggested that one way to push more power over an aging infrastructure was to increase the voltage spec and thus provide the power increase at the existing current level--not that his firm would do that, of course, but I didn't hear any of that from him
Someone suggested buying a variac to see if decreasing the supply voltage fixed the problem, but I never wanted to spend the money for one, though now with another component evidencing the same problem, maybe I should....but that would only possibly diagnose the problem, not solve it!
OTOH, the problem could be due to DC offset in the AC supply, correct?
Is there any easy/safe way to measure that in a home with not much more than a typical DMM? Or is the likelihood of DC offset on our AC circuits in a home not very high?
Thanks!