Question about NAD T973 Amplifier

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Grounding noise I purchased me t973 a little over a year ago, and use it very seldom. Then one morning I turned it on and heard a grounding sound in all speakers. I disconnected everything else (including the T-163 pre-amp), leaving only the amp and speakers. I still hear the grounding sound. I also notice that one of the 3 fans at the bottom isn't spinning.

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Re: Grounding noise

The problem with the NAD T973 power amplifiers are usally located on the power supply board.

If inspected you may notice swelling of the high value large electrolytic capacitors. In particular the 22,000uf and the 15,000uf caps.

The other filter caps such as 1000uf and 470uf as well as 3,900uf can also be faulty.

I have had this very problem and found it to be a result of the 1000uf caps specifically creating the loud humming although all amps still were working well. After their replacement, all was well again.

I have also come across the high value caps failing in these amplifiers after around 6 years of age, so would recomend replacing all the mentioned values above if near this age or older amplifier is being serviced.

NOTE: High quality and high temperature capacitors only should be used as repalcements. Mylar manufacture such items although there usally is a fair modification required to fit the 22000uf caps as they are much larger than the NAD originals but they exceed their quality.

Posted on Jul 28, 2009

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Re: Grounding noise

Pull bottom panel and get some canned air and spray around circuit board .May have a shorted capacitor to ground.Might have to use repair directory on this site.

Posted on Dec 01, 2007

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Well, the values are much more likely, 2200 and 1500 microfarad, you might check on how many zeros there really are. Also, how do you know they are failing?

It is likely they are not failing unless
they are much older than 30 years. Sources of parts include
Mouser Electronics ( There are many
sources. Knowing the correct value of the part, of course,
helps significantly. I think you might be off by a zero.

Transistors and diodes are a more likely suspect of failure. Even
these parts are quite reliable unless overloaded, then they tend to short circuit.

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