Reply to thread

Message

<blockquote data-quote="Mike Caldwell" data-source="post: 7330" data-attributes="member: 170">I&#039;m helping work on an old ( like there are any new ones) a PM4000 that has hum issues. All of the aux outs have a light to moderate amount of hum on them, turning the aux masters up and down does increase and decrease the hum. The main stereo and group outs have slight amount of hum. The matrix outs are clean with all the matrix main levels up and the matrix inputs all down, bringing up any of the matrix inputs will bring the hum into the matrix outs. All of the channel inputs are off the auxes are off. Changing power supplies did not help. My theory is that possibly there is a channel module that is causing the the hum directly on the busses regardless of the mode the channel is in.Short of pulling all of the channel modules does anyone have any ideas?Can you pull and replace the channel modules with the board powered up?ThanksMike C.</blockquote>

[QUOTE="Mike Caldwell, post: 7330, member: 170"] I'm helping work on an old ( like there are any new ones) a PM4000 that has hum issues. All of the aux outs have a light to moderate amount of hum on them, turning the aux masters up and down does increase and decrease the hum. The main stereo and group outs have slight amount of hum. The matrix outs are clean with all the matrix main levels up and the matrix inputs all down, bringing up any of the matrix inputs will bring the hum into the matrix outs. All of the channel inputs are off the auxes are off. Changing power supplies did not help. My theory is that possibly there is a channel module that is causing the the hum directly on the busses regardless of the mode the channel is in. Short of pulling all of the channel modules does anyone have any ideas? Can you pull and replace the channel modules with the board powered up? Thanks Mike C. [/QUOTE]

Verification