[wroman214]

  I recently accuired a Marantz KI Pearl integrated and in running down noise using the internal or a spearate phono section I checked for at the rear copper panel and got 60.7 volts to ground.  The Marantz has a two prong plug.  I am thinking there is something grounding out.  The internal phono seems a little low in volume but cd playback has no noise.  Any techies with any thoughts?
Walt

[Speedskater]

It's probably what an electrician would call "phantom voltage" (which is much different the a microphone phantom power supply).  Modern digital meters (DMM) have such a high input impedance, they sense the slightest leakage voltage. Try connecting a 1 meg Ohm resistor from chassis to ground and remeasure. (any value resistor from 100 K to 10 M is OK)

[Davey]

Walt,

I'm sure Speedskater is correct on this.  In the old days we all used our Simpson 260 volt-ohm-meters and you'd never notice "residual" voltage like this.  (Actually, I still use mine quite often....but that's another story.)
Many times nowadays when I'm checking AC line voltages with my DMM I attach a little 1k shunt resistor gadget across the terminals and plug my test leads into that.

BUT, you are dealing with line voltages here and it's possible that 60.7 volts (for whatever reason) might be "real."  So be careful while sorting this.

Cheers,

Dave.

[Æ]

  I recently accuired a Marantz KI Pearl integrated and in running down noise using the internal or a spearate phono section I checked for at the rear copper panel and got 60.7 volts to ground.  The Marantz has a two prong plug.  I am thinking there is something grounding out.  The internal phono seems a little low in volume but cd playback has no noise.  Any techies with any thoughts?
Walt

It is a well know, very common occurrence. Forgot exactly what it is called, why it happens, but the power transformer inside the equipment (Marantz) is what is producing (inducing?) the voltage to ground. It's a type of leakage (leakage flux?) due to the practical physics of transformer design, not an actual short.
Try flipping over the two prong power cord and remeasure again. Best power cord orientation is when you get the lowest voltage reading from equipment chassis to earth ground. If one prong is wider than the other (as is usually the case) then you'll have to use a ground cheater adaptor and file the one wide blade/prong on the cheater so that you can flip over the cord before reinserting it into the AC wall outlet. Modern wall outlets have a wide slot and a narrow slot and also a ground. The narrow slot is "hot" and the wide slot is "neutral." You need to reverse the hot and neutral and measure again. Don't mess with the wall outlet, just the cord. Some people will simply just file the wider prong on the power cord. I on the other hand will actually open up the piece of equipment and flip over (modify) the power cord internally. If your Marantz power cord doesn't have one narrow and one wide prong, then you've got it easy.
Plug in and measure, then flip it over again and remeasure. One way or the other will give the lower voltage to ground reading which would be the best power cord orientation.

[Speedskater]

In older equipment most of this voltage is from capacitive leakage in the power transformer.  Most power transformers are not wound symmetrically about the core with regards to leakage.  This is why a balanced AC power system never works as well in  practice as the ads claim.
Even older legacy equipment did some strange things with AC power and the chassis.
New equipment with SMPS power supplies sometimes have hidden but real capacitors from the secondary to the chassis.

[Æ]

In older equipment most of this voltage is from capacitive leakage in the power transformer.

Happens in newer equipment too.

[wroman214]

AE,
  I am familiar with using the polarity suited to the lowest volt to ground.  I just recheck when I got off work and reading now a  steady 64.5 volts A/C, with the cord flipped reads around 85 volts.   These are higher numbers than I am used to seeing and wondering if it could be affecting the noise I get using phono, which is similar to sound you get if you disconnect the ground lead on you phono but reduced in volume.
  There is certainly a problem somewhere.  Thanks for all the reply's.  This is the first I heard of capacitive leakage. I will check to see if get any readings across a resistor.

[wroman214]

  OK, not a HOT chassis.  But another question.  The noise I am getting is almost eliminated if I connect a wire from the chassis to house ground.  Any problem running like that?

[Æ]

  OK, not a HOT chassis.  But another question.  The noise I am getting is almost eliminated if I connect a wire from the chassis to house ground.  Any problem running like that?

Well, it looks like you are making headway. . . I still wonder if your equipment is working properly or if there is some sort of mysterious short. Deserves some more investigation, but it isn't something that can be explained to you easily.
Grounding is always good, just as long as you don't create a ground loop.

[Speedskater]

Sure you can run a wire from a chassis to your AC power ground.
This is how AP instruments did it.
Connect the other wire end to the ground lug on a cheater plug.

Not sure how to connect the other end.

[*Scotty*]

Something to think about,seeing as no one has mentioned this yet, when you have a two prong AC plug and you reverse the polarity the fuse is now in the neutral line. In the event of a circuit failure which blows the fuse, the current stops flowing but the AC hot is still connected to the equipment. 
 I switch the leads on the primary at the transformer instead of flipping the power-cord polarity at the wall outlet to avoid this situation.
Scotty

[Don_S]

Proabably just run a grouind wire from the component chassis to the center screw of the wall receptacle.  Cheater plugs come with a wire or tab to fasten to the center screw.  The purpose of a cheater plug is to connect a three-prong (grounded) power cord to a non-grounding (two-slot) receptacle. I think I have also read in the past that the center screw can be used as a ground for audio equipment using a separate wire.  Or maybe you will just get a hellacious ground loop. 

[Æ]

Something to think about,seeing as no one has mentioned this yet, when you have a two prong AC plug and you reverse the polarity the fuse is now in the neutral line. In the event of a circuit failure which blows the fuse, the current stops flowing but the AC hot is still connected to the equipment. 
 I switch the leads on the primary at the transformer instead of flipping the power-cord polarity at the wall outlet to avoid this situation.
Scotty

That is the way I always do it too, because I know how. But, not everyone is handy with tools, knows how to solder, can change it over.

There is still a circuit breaker in the circuit, way back at the breaker box, service panel.

[Speedskater]

My first thought was of a reverse cheater but that's silly.  You could use a 3 pin AC plug with no Hot or Neutral wires. Be very careful.

[Haoleb]

Connecting a large ground conductor (think 10 or 12AWG) to a central grounding point, like a ground lug on a power center, or a home made buss-bar that is connected to earth ground and then connecting the other side to the chassis of your equipment is actually a really good way to help your system out. Even though most components have grounding conductors in their power cords, if you star ground all of your equipment in this fashion you can get pretty considerable measured results when it comes to resistance to ground from each component.

You do not really want to daisy chain everything together, a seperate grounding conductor is best, and better yet is keeping them as short as possible. Not only does this ensure that all of your equipment is properly grounded but also helps eliminate noise related with ground loops etc. Instead of ground currents flowing through rca connections it will take the path of the lower resistance grounding conductor.