AC cord polarity?? Does it matter???????

Then plug in the component using the normal orientation, but with the cheater plug in place. If the component uses a grounded cord, make sure to connect the green ground wire on the cheater plug to the outlet plate screw. Turn the component on, and set the voltmeter to A/C volts.
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>>"If the component uses a grounded cord, make sure to connect the green ground wire on the cheater plug to the outlet plate screw."<<
[Jeffjarvis]
>>>>>>>>

Jeff I think you meant to say here, *do not*, connect the ground wire for the test. The equipment needs to be free of all earth grounds for the test. Infact if the type of ground cheater used is the brass or copper strap type, tape or cut off the ground strap so it does not come into contact with the receptacle cover plate screw. The screw is connected to the equipment grounding conductor. The reason the audio equipment must be isolated from earth ground is not because of the earth ground its self, it is because the equipment grounding conductor and the neutral conductor, (the grounded conductor), are connected together at the main electrical service panel neutral/ground bar.
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Munufactures usually check to make sure they have properly wired the power supply's transformer primary correctly, sometimes they miss one.

Another cause of reverse AC 120V polarity is after market power cords. Either the male plug or IEC female connector wiring is reversed. If you are using after market power cords check them for proper continuity, polarity.

If the amp is pluged into one electrical outlet and the preamp in another, sometimes the polarity is reversed at the receptacle. Check for proper receptacle polarity.

If it turns out one of your components power transformer primary winding was connected with reverse polarity and you are using an after market power cord just reverse the hot and neutral conductors at one end only. The male plug, or IEC connector end. Repeat the polarity test with the ground cheater to verify it is correct.

This test will work for a preamp or power amp. For newer two wire cord and plug equipment such as DVD or CDP players this test procedure may not work. The case, enclosure, of the unit is floating and has no electrical continuity with the electrical power supply or electrical components inside the enclosure. Another thing about CDPs and DVD/SACD/DVDA players is the fact they use multiple power supplies.
Jim

Of course if you decide to use a balanced power unit, all this is of no concern.

>>"Of course if you decide to use a balanced power unit, all this is of no concern."<<
[Nsgarch]
>>>>>

Maybe, True if all the audio equipment connected by ics is pluged into the same balanced power unit.
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Nsgarch, What is your thoughts of feeding a balanced power unit from 120V? Jmho, I believe there would be better isolation if a balanced power unit was feed by 240 volt.

Here is some reading material. Make note of how the utility companies bond the high voltage neutral and all the secondary neutrals together at every utility transformer.
This can't be good for AC noise....
http://www.mikeholt.com/documents/strayvoltage/pdf/DangersofStrayVoltageandCurrent.pdf
Jmo it appears to me the only way to get total AC isolation is with an isolation transformer fed from 240 volt.
Jim

Nsgarch, I am not sure.....

>>"Of course if you decide to use a balanced power unit, all this is of no concern."<<
[Nsgarch]
>>>>>

>>'Maybe, True if all the audio equipment connected by ics is pluged into the same balanced power unit."<<
[jea48]
>>>>>>>>>

After thinking about the balanced 120V (60V-0V-60V) system I am not sure one would not be in the same boat.

It's those darn ICs that connect the audio equipment together.

Two hot 120 volt conductors.
I will call them L1 and L2, 120V.

A power transformer, for say, a power amp.
It is nothing more than an isolation transformer. It has a winding polarity relationship between the primary and secondary windings.

For sake of argument lets label the primary leads H1 and H2. The secondary leads X1 and X2. If the manufacture of the transformer labeled the leads correctly, H1 polarity match is X1 and H2 polarity match is X2.

Connect the audio power transformer primary to the 120V power from the balanced power unit.
(L1 to H1) (L2 to H2). If all the audio equipment power transformers are wired the same the the secondary AC polarities will be the same and so the DC power supplies. (Providing a primary winding polarity to power supply polarity were correct to start with)

What happens if one of the audio equipment power transformer's primary connections is reversed?
(L1 to H2) (L2 to H1)

Any thoughts??

Jea, a 240V line is inherently "balanced". Its ground and neutral are the same (center) conductor, with a potential of +120v on one side and -120V on the other (which reverses every 60 sec. of course.) BTW, I don't believe European 240V power is configured this way (at the outlet), but somebody correct me if this is wrong.

Now to get balanced 120V is a whole 'nuther matter. First you get a great big toroidal transformer and feed it 120V +/_ into one tap and zero volts (neutral) into the other. In a second, identical winding, you take the power out at 60V +/_ tap and 60V -/+ tap and feed one to each blade of the AC plug. To keep the drama queens at U/L happy, you create an artificial ground/neutral for the center ground pin of the plug/receptacle. This is done through some kind of circuitry which U/L is willing to certify provides shock protection ;~)) but it's not an "earth" ground.

If your equipment circuit designer or assembler has been less than attentive as you postulate, then balanced power will save his/her ass because both primary leads are being fed equal (60V) voltage in a "push-pull" arrangement around (or across) an "imaginary" ground (rather than the normal zero volts in one lead and plus-or-minus 120V in the other.) So in the balanced-power-fed component, circuit polarity relative to ground disappears along with any polarity mismatches in the wiring.