Grounding A Preamp


I have a NAD 1155 preamp with a nasty buzz in the phono stage. It's not a phono grounding issue, because I checked that. After the preamp is on ~40 minutes, the buzz goes away after I touch the faceplate. So I am acting as a ground. Should I just run a wire from the preamp to a electrical outlet screw, or what? I am at a loss.

TIA,

Lee
licoricepizza
Try that first.
I have a NAD 1155 preamp with a nasty buzz in the phono stage.

It's not a phono grounding issue, because I checked that.
How did you check that?

If you disconnect the TT from the NAD (ics as well as TT ground wire) is the buzz still present?

Should I just run a wire from the preamp to a electrical outlet screw, or what? I am at a loss.
If the NAD has a 2 wire cord and plug I would not advise that. And I do not believe it will make any difference in regard to the buzz.

The TT does have 2 prong plug. To check if the TT was the offender, I completely disconnected, ground wire and all. the buzz was still there. To this untrained ear, it sounds like a 60Hz buzz, like you'd get from a fluorescent light, or a wall-wart transformer.
01-29-09: Licoricepizza
The TT does have 2 prong plug.
How about the NAD preamp?

To this untrained ear, it sounds like a 60Hz buzz, like you'd get from a fluorescent light, or a wall-wart transformer.
Is the buzz sound being heard from the speakers?
Or is the sound, a mechanical sound, coming from the preamp itself?
The preamp also has a 2 pronged plug. The buzz is coming from the speakers, and is volume dependent.
01-30-09: Licoricepizza
The preamp also has a 2 pronged plug. The buzz is coming from the speakers, and is volume dependent
Well if I understand you correctly at on point in your trouble shooting you isolated, disconnected, everything from the inputs of the preamp and the buzz was still present. Correct?

The buzz varies with gain of the volume control.

Did you check the ics that connect the preamp to the power amp for corrosion both ends RCA plug to RCA jacks of the equipment?

Unplug and plug them back in several times and see if that helps.

Try a different pair of ics.

When the ics are plugged in try gently moving the ics plugs at the jack connection at the preamp first then at the power amp.

When you touch the preamp with your hand and the buzz goes away, jmho, that sure sounds like a signal ground problem to me.

Your body is not acting like an earth ground. I think it is working more like a capacitor. Maybe an electronics EE will comment more on that one.
I didn't check the interconnects for corrosion. I did change the ICs that go between the amp and the preamp. allow me to clarify one thing: when I touch the preamp, SOMETIMES the buzz goes away, but not always. I figured that if I stopped the preamp from buzzing, I would leave that unit powered on while not listening. The amp, and everything else was shut off. That practice didn't work either. The buzz was there when I turned the amp on again.
Licoricepizza,
Question:
If you select, say, CD for the listening input on the preamp, is the buzz present?

If not and it is only present when the preamp listen selector switch is set to phono..... there may very well be a problem with the preamp.
All the inputs except phono are dead quiet. I do know how to wield a soldering iron, so I guess I'll have to get out the Fluke meter, and tear apart the preamp...