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Newb post - NAD 3020 in need of repair
Newb post - NAD 3020 in need of repair
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Old 27th February 2017, 04:29 PM   #1
scottinfinity is offline scottinfinity
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Thumbs down Newb post - NAD 3020 in need of repair

Hello from London town, UK.

I recently picked up this Nad 3020 from a flea market (dirt cheap) as a bit of a gamble. Cosmetically the front is damaged and the sound coming out of it is less than fantastic. As follows is a YouTube link showing the amplifier in action.

https://youtu.be/tb3bagdA5GA

As you can see, it's sounding very crunchy and distorted and also perhaps quieter than one would expect.

Does anyone have any suggestions for where to start fixing this potentially brilliant amp?

I'm not myself trained in electronics but I have those around me who can translate any response you give!

Cheers!

(EDIT - Might I add that the song being played ought to sound like THIS!)

-Scott

Last edited by scottinfinity; 27th February 2017 at 04:41 PM.
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Old 27th February 2017, 05:02 PM   #2
scottinfinity is offline scottinfinity
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Old 27th February 2017, 05:11 PM   #3
Mooly is offline Mooly  United Kingdom
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Newb post - NAD 3020 in need of repair
Welcome to diyAudio Scott

Having seen the damage to front I think checking for physical damage and cracked print could be a good start.

Faults like this always follow a standard procedure. First check that all the DC supplies are correct to both power amp and pre amp stages. Check the DC offset and DC bias of the output stage. That may show up some anomalies. After that its simply a case of using a test tone (signal generator or test CD) and tracing the signal through using an oscilloscope. That will instantly split the problem area in half... front end or power amp section.
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Old 27th February 2017, 06:51 PM   #4
scottinfinity is offline scottinfinity
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Quote:
Originally Posted by Mooly View Post
Welcome to diyAudio Scott

Having seen the damage to front I think checking for physical damage and cracked print could be a good start.

Faults like this always follow a standard procedure. First check that all the DC supplies are correct to both power amp and pre amp stages. Check the DC offset and DC bias of the output stage. That may show up some anomalies. After that its simply a case of using a test tone (signal generator or test CD) and tracing the signal through using an oscilloscope. That will instantly split the problem area in half... front end or power amp section.
Thanks for the swift response!
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Old 27th February 2017, 06:54 PM   #5
Mooly is offline Mooly  United Kingdom
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Newb post - NAD 3020 in need of repair
You're welcome. Good luck.
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Old 27th February 2017, 07:51 PM   #6
VictoriaGuy is offline VictoriaGuy  Canada
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Newb post - NAD 3020 in need of repair
As Mooly said....
With that damage, I'd suspect cracked solder joints where some of the switches are attached to the circuit board.
If you have a meter, one of the first things to do is check for DC on the speaker terminals a.k.a. DC offset.
I'd also use my 'dispensable' 'test' speakers, not good ones while testing.

Have you tried CD or tuner as a source (vs phono)?

You'll find that the schematics and service manual will be useful for troubleshooting.
Try:
https://www.hifiengine.com/manual_li...nad/3020.shtml
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