Originally Posted by dom08
alright what happens is.. ill turn the amps on; the hum only starts when there is sound playing.. the master volume no matter how much it is turned up or down will not make the hum go louder or softer. Once i turn the master volume (all on the receiver) to 0.. it kills all sound, once i turn it up a notch, the hum starts...
i hope that clears it up??? let me know and i can try to explain it better
Still some conflicting evidence. a) >>the master volume no matter how much it is turned up or down will not make the hum go louder or softer<< vs. b) >>Once i turn the master volume (all on the receiver) to 0.. it kills all sound, once i turn it up a notch, the hum starts...<<
1) Can you confirm that the hum is present when you select, say, a CD or DVD input, while the player is stopped? Does it matter if you change sources? Can you also confirm that the hum in this case behaves as in a), or does it in fact vary in loudness as the volume changes?
2) It looks like the power amp has its own volume controls. If you turn them all the way down, does the hum go away?
3) Assuming Yes to 2), do you hear the same hum if you drive a speaker directly from the AVR? Leave the amp connected and humming--just move the speaker connection, and since the other speakers are making hum, you will need to either check the AVR's speaker very closely, or temporarily reduce the amp's volume (and hum) so you can hear if it is coming from the AVR or not.
If the hum is coming from the AVR, try disconnecting the inputs to see if one of them is causing it. Often, a cable/sat box brings in another ground from the antenna, and this can cause hum.
If the AVR can be shown to be totally hum free when standing alone (no other inputs/outputs, and speakers directly connected), then the issue is to find which of those external connections, or the combination, is introducing the hum problem.
If the AVR has a hum even when running bare bones, and it is not being induced by some unusual electrical field nearby, it would appear to have an internal power supply problem.
Hence, all this effort to try to figure out where it originates.