NAD 3020e recapping adventure - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th April 2011, 04:17 AM   #1
diyAudio Member
 
Join Date: Apr 2011
Default NAD 3020e recapping adventure

Hi All,
So I bought a mint NAD 3020e at a garage sale a few weeks ago for a steal, plugged it in much to my surprise, it works perfectly.
Now having had a vintage amp (Rotel 1210) actually explode on me before, I know that old amps need re-capping at this age & not content with a time bomb on my desk, i decided to replace the main power capacitors.

So last night I successfully replaced the 2 main power caps (35v 4700uF) with 50v 4700uF caps and once again the amp works no worries

However,
Now, the speakers emit a slight whump & actuate briefly when i turn the amp on or off. I've had old amps do this on me before, but usually a lot louder..
I would have thought the new power caps would smooth this out, or should i really be re-capping the whole damn thing?
Any ideas?
  Reply With Quote
Old 8th April 2011, 05:12 AM   #2
diyAudio Member
 
eclectic2k's Avatar
 
Join Date: Nov 2005
Location: Silicon Valley
I'd guess the higher ESR of the aging capacitor was limiting the inrush current into the cap. The new cap is likely filling faster, and the larger inrush is causing the turn-on thump.

It's not an especially powerful amp, and not an especially high capacitance, so I'd assume that the "whump" is not very loud either.

If it concerns you, you'll maybe want to look into adding a slow start of some form or another...
  Reply With Quote
Old 8th April 2011, 06:50 AM   #3
diyAudio Member
 
Join Date: Apr 2011
Ahh thanks for that, yeah the 'whump' is soft & isnt too worrying, I was mainly just curious as to the cause of it with new components.

Cheers!
  Reply With Quote
Old 5th May 2011, 10:12 AM   #4
diyAudio Member
 
Join Date: May 2011
Hello,

I had my amp working for over 10 years and it did this every time I turned it on, I believe it was a "feature" of amps of this era
  Reply With Quote
Old 5th May 2011, 01:36 PM   #5
robotc is offline robotc  Australia
diyAudio Member
 
Join Date: Apr 2007
Location: Melbourne
Hi
I have the same problem with switch-on thump. I recall that it seems to be common with this model.
I did a bit of investigation and playing around with the amp a while ago. I found that the thump comes from the preamp. (When I removed the U-link joining the pre and power amps the thump didnt happen.)

There are muting FET's at the output of the preamp with a timing circuit to delay their turn on. I played around with the component values of the circuit and this changed but never completely removed the thump.
For various reasons I never finished my testing. I would be interested to know if anyone has managed to solve this problem.

Bob
  Reply With Quote
Old 7th May 2012, 03:13 AM   #6
Comsat is offline Comsat  United States
diyAudio Member
 
Join Date: May 2012
Location: Chicago, IL
I just picked up a 3020e myself and while I like the sound I've noticed that one channel (L) is slightly louder than the other (R). I'm assuming that this could be due to aging capacitors, correct? I'm just wondering how far to go in replacing the caps? Start at power caps and go from there? I'd still have to order the caps from the web so I'd rather have everything or more than I need when I start the job. Anyone have any insight?
  Reply With Quote
Old 7th May 2012, 01:52 PM   #7
asounds is offline asounds  Portugal
diyAudio Member
 
Join Date: Dec 2007
Location: (The magnificient) Lisbon
I would replace all the caps. That will also improve the sound of the amp. If you need the schematic to check all the values and make a general overall let me know. That bump could be also some DC on the exit and the amp needs to be re-adjusted.
The 3020 is probably the most famous amp in Hi-Fi history and for a reason. Great sounding amp
  Reply With Quote
Old 7th May 2012, 06:58 PM   #8
Comsat is offline Comsat  United States
diyAudio Member
 
Join Date: May 2012
Location: Chicago, IL
Quote:
Originally Posted by asounds View Post
If you need the schematic to check all the values and make a general overall let me know.
Any assistance helping me get a parts list together would be totally appreciated.

Quote:
Originally Posted by asounds View Post
The 3020 is probably the most famous amp in Hi-Fi history and for a reason. Great sounding amp
I'm eager to find out if the 3020e actually lives up. I've been using an 80's Onkyo TX-28 which is incredibly musical but I've always wanted to wade into the NAD pool and see how the water is.
  Reply With Quote
Old 14th May 2012, 09:41 PM   #9
Comsat is offline Comsat  United States
diyAudio Member
 
Join Date: May 2012
Location: Chicago, IL
Again, any help putting together a parts list for my project would be appreciated. I'm perfectly handy with a solder iron and I've recapped some old tube guitar amps but I'm not an engineer.
  Reply With Quote
Old 15th May 2012, 07:03 AM   #10
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
Quote:
I'm assuming that this could be due to aging capacitors, correct?
I wouldn't think so. As the 3020 was more of a budget amp, I guess the power supply is shared between channels, so it cannot affect only a single channel.

Further, different gain comes more likely from either a cheap channel balance pot or - less likely - from manufacturing variations in the transistors.

You might recap the amp for fun nevertheless if you feel like it.

Hannes
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Couple of Nad 3020e questions soupdragon Solid State 4 14th February 2010 03:02 AM
nad 3020e bull041161 Solid State 18 29th March 2009 01:38 AM
Another DIY Turntable adventure JesseG Analogue Source 11 2nd July 2007 05:17 AM
My UcD adventure justcallmefrank Class D 71 17th June 2006 03:27 AM
Problems with NAD 3020e pho_boi Solid State 3 1st February 2006 10:02 AM


New To Site? Need Help?

All times are GMT. The time now is 05:56 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2