NAD 3020A No sound after changing capacitors.

[Nickaliath]

Will upload a picture after this post. It makes it even more confusing with the various layouts of these amps.

Yeah, I've read a few posts regarding these J111 JFETS. mainly people talking about them not being very good.

The 1000uf 6.3 was replaced like for like. I also read in a different post someone was talking about changing that for a 47uf 50v or 63v. They said to replace C531, C532 and C533 to the above.
This was apparently from an ex technician at NAD.

Also I saw mentioned that they quite often did random small changes to components, So they don't always match up exactly.

[Nickaliath]

https://ibb.co/PGZcP7b

[Nickaliath]

Its now working!!!!

I decided to just change that capacitor over on the C531 from the 1000uf 6.3v to the 47uf 50v and it now comes off mute after a brief pause. Which is obviously usual.

The C533 is already a 47uf 50v and the C532 is 4.7uf 50v. Both same as what was taken out.

Its so weird that it caused it not to work, Considering that was what was in there before. I even tried putting the old cap back in before that, In case the new was faulty.

Hopefully this issue will help others with a similar problem in the future.

I have learnt my lesson when changing caps and will check every few fitted.

Thanks again for everyone's input, Its appreciated.

[Bazz4CQJ]

Well done! I'll make a note of this thread in case I ever need to do any work on beloved NAD tuner, bought new around 1987.

Talking Heads' "Stop Making Sense Tour" is out on Imax today and being promoted on radio; high time I re-visited that album!

B

[Michael Maurice]

Originally Posted by Nickaliath

Its now working!!!!

I decided to just change that capacitor over on the C531 from the 1000uf 6.3v to the 47uf 50v and it now comes off mute after a brief pause. Which is obviously usual.


Its so weird that it caused it not to work, Considering that was what was in there before. I even tried putting the old cap back in before that, In case the new was faulty.

I don't have the circuit but you'll probably find that C531 is some sort of delaying circuit, what has happened is that the delay time has ben increased by 20 times or it probably couldn't even latch on. Putting 60 -80V across a 6.3V capacitor isn't a good idea. I'm surprised it didn't explode!

[Nickaliath]

Originally Posted by Michael Maurice

I don't have the circuit but you'll probably find that C531 is some sort of delaying circuit, what has happened is that the delay time has ben increased by 20 times or it probably couldn't even latch on. Putting 60 -80V across a 6.3V capacitor isn't a good idea. I'm surprised it didn't explode!

I wouldn't have tried it, If it wasn't listed like this on the NAD service manual.
It shows that the C531 should be 47uf 50V. So not sure why it had the 1000uf 6.3v in there?
I am presuming this is why the NAD tech. stated c531, c532 and c533 should be 47uf 50v.

[Radio Wrangler]

It's also possible that the oversized and over voltaged capacitor was leaking so much that the switch on delay timer would never have turned the thing on.

David

[Goldie99]

Good that it's working again, but I'd still suggest to check the voltage across your new C531 cap while the amp's running - I'll be surprised if it's not at least 70V...

I don't understand a NAD tech. recommending those 3 all be the same, at 47uf/50V, that doesn't match any NAD SM I've ever seen for that muting circuit.
You mentioned previously that you have C532 @ 4.7uf/50V and C533 @ 47uf/50V. Those two are what I'd expect, but not a 47uf / 50V for the C531.

[ben]

Good news - Persistence pays off! As Michael Maurice said, I am surprised that low rated cap did not fly across your workbench on powerup. Perhaps the cap was mislabelled too!

[stevehertz]

Don't recap vintage hifi used in the UK. If there's cause to believe that the unit is not working properly then use established fault finding methods to look for a fault. In the US where the fad of recaps came from there is perhaps some justification given that the temperature there can be very high. Couple this with Americans having large houses and as a result a tendency to run their hi-fi's at high volume, then all this adds up to stress as far as electrolytic are concerned; they don't like long term exposure to high degrees of temperature.

[Jez1234]

My experience as someone who services high end hi fi for a living leads me to strongly disagree with that.

[paulsherwin]

Changing all the electrolytics shouldn't do any harm, even if it's usually not necessary. The problem is that it's a fiddly long winded process, with plenty of opportunities to introduce errors. This is particularly the case if the person doing the recapping has limited expertise or experience.

[Jez1234]

With some specific products, after say 8 years regular use it would indeed usually be unnecessary, but with others, after a similar amount of use, it would be necessary.
It would be a particularly long and thankless task to try to make any such list and there are always the exceptions that prove the rule of course.
To check each electrolytic for both capacitance, leakage and ESR would take as long as to just replace them (generally leakage is not tested as it requires removing the cap to test it. Depending on what the cap is connected to and the test voltage etc of the capacitance or ESR meters it may be necessary to remove a few just to test capacitance and ESR anyway).

An aspect of the job which is less reported is that simply sourcing and ordering all the electrolytic caps required to completely recap an amp can be a bigger job than actually changing them. Sometimes there is very little clearance between a cap and the casework or between cap and the next cap along and so you have to make sure you don't get caught out by this by ordering slightly physically larger parts... then there is the lead pitch to consider, and foibles such as smoothing caps with 3 or 4 pins which may have to be replaced with conventional snap in ones. All this is much worse post Covid and the electronics components shortage (which is still not entirely back to normal) hence I wish I had a fiver for every time I've found the right electrolytic with a good rating for life time and at a fair price only to find that when I try to order them I get another screen telling me "Available for back order. Estimated delivery 5/4/24"

[Station X]

Originally Posted by Jez1234

My experience as someone who services high end hi fi for a living leads me to strongly disagree with that.

In theory changing all the capacitors in a piece of equipment shouldn't do any harm and may do some good. I have no doubt that you are capable of fitting the correct replacement capacitor of the correct value in the correct place the correct way round. Should you make a mistake, let's face it we all do, then I have no doubt that you are capable of finding the fault.

Unfortunately that doesn't apply to all our members. Fault finding is an alien concept to them. Their repair technique appears to be change all the capacitors and any out of tolerance resistors then give the pots and switches a squirt of Servisol. If it doesn't work then ask for help in the forums. Some of these members have hundreds of posts to their credit, but never seem to learn anything.

In my 20 odd years of moderating these forums I've seen several cases where a working radio or record player has never worked again after someone decided to change all the capacitors.

Discussions of this nature will still be going on long after I'm gone.

[knobtwiddler]

I recently re-capped a hot-running (200mA on +/- 50V rails - and regulated VAS stage) amp from 1978 and tested the caps afterwards.

I haven't come across a faulty Rubycon from the '80s yet (even 85-degree ones, used next to Vregs with scorched outer wrappers!), and the Nippon-Chemicon shown in above thread speak for themselves ^

[Jez1234]

Oh it can happen yes! I've had several jobs come my way which basically involve putting right the results of amateur bodging.... though I'm often inclined to turn them down as it can be the job from hell to know there was a fault stopping the unit working before the bodger got at it and then to have to work out which fault caused the initial failure and which were caused by the amateur attempts to fix said fault.

[Nickaliath]

Originally Posted by ben

Good news - Persistence pays off! As Michael Maurice said, I am surprised that low rated cap did not fly across your workbench on powerup. Perhaps the cap was mislabelled too!

I did double check this one and it was what was in there previously, So definitely odd.
I read on another forum post with a similar issue, The guy also had the 1000uf fitted in the same system.

[stevehertz]

I have a large collection of high end, mainly Japanese hifi receivers and tuners from the late 70s to the early 90s when Japanese companies largely pulled out of the true hifi market and moved towards faux stacking systems with flashing multi coloured LEDs. Virtually all of the sets came to me faulty, often with hard to find, complex faults. Apart from main smoothers I have not needed to replace a single board mounted electrolytic capacitor. All of my sets have been restored to - to my ears - perfect working order; RF, audio, the lot. And as a qualified electronics engineer, musician, former small studio owner and builder of monitor level speakers I'm no mug when it comes to assessing sound quality. Now.. will any of those thousands of electrolytics in those sets be 'faulty'. The answer is almost certainly yes to some degree. The point is, the 'degree of faultiness' that they may have is not affecting my listening enjoyment. Compare that situation (essentially 'nothing' is wrong) with the time, money and hassle of replacing all of those caps? My experience tells me that the shotgun replacement of all electrolytic caps in modern hifi equipment is, in many cases, more for the 'heads' of those wanting it, and a nice earner for those doing it on professional basis. The latter I have no qualms with whatsoever.

[knobtwiddler]

100% in agreement, Steve. I think known rogue electrolytic caps such as Frako (ubiquitous in Studer, Revox and even some of the most desirable Neve consoles) have given credibility to the practice of shotgun replacement. Not all caps are like Frakos (with their green gunk and DCR)!

Some of the '80s SSL consoles (and Neve) eat through caps because they run 24/7 and get incredibly hot (the late 80s and 90s saw analogue console OEMs packing more and more features into each channel strip, consequently needing monster PSUs and generating a lot of heat). Your amateur audiophile might read that studio engineers have to grapple with the caps in a 1980s SSL and think it means that their preamp needs re-capping.

[locknut]

I'm not a fan of blanket replacement of capacitors.

Sansui amplifiers from the 70s have a very distinctive warm sound. There are plenty of anecdotes out there where folk have had all electrolytics replaced by modern types, only to be disappointed by the results.