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Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

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RE: Power Cord Polarity

Posted by jea48 on August 2, 2017 at 16:57:49:

The old supposed correct way to find "correct" polarity would be to plug the unit in and measure the chassis voltage with ac meter to ground, the supposed correct polarity would be the one that has the LEAST amount of ac on the chassis and then ground the chassis. What I am finding is the exact opposite my stuff sounds better the other way.

How old is the unit? 1950s/ 1960?s The old stuff often used an AC noise filter connected to one of the AC mains lines to chassis. Those old filter caps go bad and leak AC voltage to the chassis. That can skew the power transformer primary winding leads proper AC polarity orientation voltage measurement test for the lower of the two winding leads to the chassis measurement.

Look for the cap to see if one was used. Isolate, disconnect, it from the chassis and then do the polarity test.