Spooky ground loop

[dyche01]

I seem to have a weird ground loop problem. I have a Dual 1245 running through my Marantz 2238B. I usually plug the TT into one of the power outputs on the back of the receiver. For a long time I had not problem. Now, however, if the unit has been off for a while, when I turn it on again I get a strong 60 Hz hum.

If I unplug the TT power cord the hum goes away. The spooky part is that, if I plug the power cord back in, the hum does NOT come back. I have now gotten in the habit of leaving the TT unplugged until after the Marantz powers up and now I never have a problem with hum.

This must be something related to the relay I hear kicking over after a second or so after I turn on the Marantz.

Any thoughts?

 

[ripblade]

I assume the AC plug is not polarized? Have you tried reversing it?

 

[dyche01]

The plug isn't polarized and the hum goes away when I pull It out and put it back in, regardless of orientation.

 

[woodj]

May be wrong, but it doesn't sound like a ground loop problem.

 

[rothwellaudio]

Sounds like it might be a bad/dirty contact somewhere. Sometimes just a slight temperature rise caused by equipment being on for a while can cause enough expansion to make a contact open (or close). Try giving the plug/socket a good clean. Cleaning relay contacts isn't so easy though. Maybe the relay will need to be replaced.