Hi all,
new to the site and hope someone out there can help me with my issues.
I have a NAD 3020 series 20 purchased new here in UK in '82/'83. I am no audiophile rather listen to the music but the NAD has been well paired with a Project 2 TT and a couple of Mordaunt Short speakers.
About 5 years ago it developed the buzz (light sabre) at power on in both channels that disappeared after about 1/2 sec, didn't really bother me and had no effect on the playback as far as I could hear. Roll forward a couple of years and the buzz grew to about 2 secs and faded but the right channel would cut out and then suddenly cut back in and be fine. The volume control made no real difference and all the tone controls worked fine. No distortion on playback. I could live with it just.
Moved house last year and after 18 months set up system and buzz still there but right channel now totally dead and can't be coaxed into life. If you have the amp switched on and power up at the wall socket then the buzz disappears and fades to a hum if you on/off a few times and if you pull the amp yokes at the back there is no buzz. I have also connected a separate phono/preamp to the power amp stage and both channels loud and clear so issue is in the integrated pre amp stage. I have had it apart and looked for bad connections, burnt out components, leaky caps and reflowed odd connections to the board but no luck. Also this seems to be a hybrid as the internal layout follows the 3020A but is badged as a series 20 with a mute button? Trawling the net there are fixes for certain issues re the problems focussing on the caps C513 – 518 and C531-533 but as I cannot find a service manual for the 3020A can’t check the circuit.
I am fully capable of carrying out repairs/ replacing components but before I start pulling them all out could any of you give me a heads up as to where to start? I really like this amp, could just buy a replacement but it has been a good servant and want to get it up and running and then maybe move on to a total recap. I always prefer to fix rather than dispose.
Thanks in advance
new to the site and hope someone out there can help me with my issues.
I have a NAD 3020 series 20 purchased new here in UK in '82/'83. I am no audiophile rather listen to the music but the NAD has been well paired with a Project 2 TT and a couple of Mordaunt Short speakers.
About 5 years ago it developed the buzz (light sabre) at power on in both channels that disappeared after about 1/2 sec, didn't really bother me and had no effect on the playback as far as I could hear. Roll forward a couple of years and the buzz grew to about 2 secs and faded but the right channel would cut out and then suddenly cut back in and be fine. The volume control made no real difference and all the tone controls worked fine. No distortion on playback. I could live with it just.
Moved house last year and after 18 months set up system and buzz still there but right channel now totally dead and can't be coaxed into life. If you have the amp switched on and power up at the wall socket then the buzz disappears and fades to a hum if you on/off a few times and if you pull the amp yokes at the back there is no buzz. I have also connected a separate phono/preamp to the power amp stage and both channels loud and clear so issue is in the integrated pre amp stage. I have had it apart and looked for bad connections, burnt out components, leaky caps and reflowed odd connections to the board but no luck. Also this seems to be a hybrid as the internal layout follows the 3020A but is badged as a series 20 with a mute button? Trawling the net there are fixes for certain issues re the problems focussing on the caps C513 – 518 and C531-533 but as I cannot find a service manual for the 3020A can’t check the circuit.
I am fully capable of carrying out repairs/ replacing components but before I start pulling them all out could any of you give me a heads up as to where to start? I really like this amp, could just buy a replacement but it has been a good servant and want to get it up and running and then maybe move on to a total recap. I always prefer to fix rather than dispose.
Thanks in advance
thanks Mooly, the schematic is correct for my layout. I will start with these three caps and see what happens
Thanks guys for replies. I did try one more attempt to correct the two issues, I left the amp on for 5 hours and the buzz/distortion/light sabre is still there on power up; however, amazingly the right channel has burst back into life. I can only assume the caps in the signal path have "reflowed" after a long lay off? I switched off over night and this morning the same result so one issue down. I will replace C531-533 as these seem to be the common cause of the power on noise? I will eventually get round to replacing the other caps mentioned but am leaning to the "if it ain't broke don't fix it" mantra.
As regards replacement caps what brands do you lean towards Elna, Panasonic FR/FC/FM or Nichicon?
As regards replacement caps what brands do you lean towards Elna, Panasonic FR/FC/FM or Nichicon?
For a NAD any reputable commercial grade 105C rated caps are perfect. Don't stress over brands, and always buy from authorised distributers.
The channel that goes dead suggests something else might going on with that one.
The channel that goes dead suggests something else might going on with that one.
For the right channel issue, which i doubt is cap related, try checking for any damaged solder joints, esp. under the rear phono sockets, on any of the controls, and on any ribbon cable joints. After prolonged storage, it may also be worth cleaning the headphones socket, the amp output signals all go via that socket, also to the speaker terminals.
Been some while but have just got round to replacing the three caps mentioned. I also for good measure decided to replace the large filter caps whilst I was at it and had to strip the chassis down and lo and behold one of the caps legs was disconnected from the board so I am not sure exactly how much of an effect having three instead of the four would have on the DC supply , less smooth I would assume and also shorting.
Anyway all in and buzz and hum all gone so all good.
Maybe get round to replacing the caps in the signal path but at moment not going to "fix what is not broke"
On to sorting out a NAD PP2 now!
Thanks to all for help
Anyway all in and buzz and hum all gone so all good.
Maybe get round to replacing the caps in the signal path but at moment not going to "fix what is not broke"
On to sorting out a NAD PP2 now!
Thanks to all for help
Good result 👍
If you do look at changing caps in the signal path then please don't just rely on the circuit diagram and the board layouts (for polarity or even values etc). There can be errors. Replace like for like as to what is actually fitted, don't pull them all out and then rely on the diagram to try and see what goes where and which way round it goes. We see so many recaps go wrong because of this 🙂
If you do look at changing caps in the signal path then please don't just rely on the circuit diagram and the board layouts (for polarity or even values etc). There can be errors. Replace like for like as to what is actually fitted, don't pull them all out and then rely on the diagram to try and see what goes where and which way round it goes. We see so many recaps go wrong because of this 🙂
Hello everyone, I am new to this forum and I am so glad you have this thread. I quite literally had the same problem as Helios1997. Thanks to all of the brilliant information I did what Helios did. I changed C531, C532 and 533 along with all 4 filter caps Although I must say I almost did not install them because they were so much smaller than the old ones. But I was assured by my local supply store that they would not only work but that they are much better than the originals. He was absolutely right. My power on hum is gone and it sounds like I breathed new life into the amp. Thanks again everyone.