Hi. My old Nad 314 has some channel problems, it seems the speaker relay needs changing. While I am at it, I was thinking to change all the electrolytic capacitors, the amp was sitting idle for about 8 years. There are 38 caps on Preamp + Power Amplifier which I am thinking to replace with caps of same voltage and capacitance, a mix of Elna Silmic II, Nichicon KA και Nichicon FG (I can’t find the same model for all on Mouser).
In the Power Supply there are 16 caps, many people suggest that bigger caps in V and uF are used, so I’m thinking of changing the originals with a mix of (available on Mouser) caps as below:
10V 22uF ---> 16V 27uF Nichicon PW
25V 10000uF ---> 35V 12000uF Cornell Dubilier
50V 100uF ---> 63V 120uF Nichicon HE
50V 10000uF ---> 63V 12000uF Cornell Dubilier
100V 4.7uF ---> 150V 6.8uF Vishay
100V 47uF ---> 100V 47uF Nichicon HE
100V 680uF ---> 160V 680uF Cornell Dubilier
Do you think it’s better to stick with the original values or increase them? Does the above list seems ok to you? Something else I am not entirely sure is that some of these larger caps replacements I have found are snap-in types, how can I check if the originals are of the same type? Thank you.
In the Power Supply there are 16 caps, many people suggest that bigger caps in V and uF are used, so I’m thinking of changing the originals with a mix of (available on Mouser) caps as below:
10V 22uF ---> 16V 27uF Nichicon PW
25V 10000uF ---> 35V 12000uF Cornell Dubilier
50V 100uF ---> 63V 120uF Nichicon HE
50V 10000uF ---> 63V 12000uF Cornell Dubilier
100V 4.7uF ---> 150V 6.8uF Vishay
100V 47uF ---> 100V 47uF Nichicon HE
100V 680uF ---> 160V 680uF Cornell Dubilier
Do you think it’s better to stick with the original values or increase them? Does the above list seems ok to you? Something else I am not entirely sure is that some of these larger caps replacements I have found are snap-in types, how can I check if the originals are of the same type? Thank you.
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No point in changing values.
Little point in changing capacitors. Has anyone ever experienced a bad cap from circa 1997? They were top quality then.
Little point in changing capacitors. Has anyone ever experienced a bad cap from circa 1997? They were top quality then.
I had the 304, which is similar to your unit. Those 680uF caps (and a few others) in my unit suffered a lot from heat and measured around 420uF (I have photos, need to find them). You can replace them with some fresh and good quality Nichicon or Parasonic, etc rated 105*C
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For a NAD amplifier made in Taiwan most likely capacitors inside are also Chinese probably lelon or teapo ...both of them horrible brands in terms of stability and 10 times worst when high temps are involved ...
So yes a replacement to a machine that was sitting at idle ( very wrong i think ) for 8 years expect all small ones to be either toasted or half blown ...
Though spending this type of money and this quality of capacitors will take you nowhere and expect hardly a few things to change soundwise
All qualities of your parts will be consumed inside the way the NAD works You may as well use an external bank of caps like 120.000uf as an experiment still you will understand that it doesn't worth the investment
Kind regards
Sakis
This year only seems that we will close the year far above 20.000 capacitors replaced in about 1500 audio machines ....
It is only June exactly half the year and we are as we speak at about 12.500 capacitors ...
Thank you very much for the answers but I am still confused about how I should proceed. The cost of the capacitors I have listed above is about 70 euros. If I stick with the original values it will be lower. Should I leave them as they are, replace them with the same values or increase only some of them?
I would rather not spend money I don't have on things I don't need (George Carlin ftw) but I really like my old buddy Nad and would like to see it sing again as it did back then.
I would rather not spend money I don't have on things I don't need (George Carlin ftw) but I really like my old buddy Nad and would like to see it sing again as it did back then.
As far as the values of electrolytics is concerned the originals are probably rated at + - 10% so a few microfarad difference will not cause any harm. Before you tear it apart it would be worth obtaining an in circuit ESR meter. They are not expensive these days and I have found mine invaluable. I do however have a healthy mistrust of all electrolytics.
This is partially wrong Help us in a way not to create urban legends inside this forum .
Rules are
1) smoothing capacitors at any place after the rectifier and before the regulation : you can go as high as you like with no limits.
Problem is that above a point rectifier will be stressed and you need to replace accordingly .
2) after regulation you should keep the original value but you may play with quality /temp/voltage/bypassing ...beefing up a capacitor there might backfire your regulator upon shut down if this capacitor stays charged more than the rectifier capacitor.
3) you cannot touch anything in timing circuits ...obviously messing up there might change the time constant or level of protection on the amplifier If it makes you feel better mess up with the rest quality /temp/voltage/bypassing.
4) local decoupling beefing up to double the value for example may result to parasitic oscillations the rule high as much as you like doesn't apply here beef up there and you may enter the trouble zone.
Often here you see wise guys redesign a pcb of a known amplifier with the addition of 2x470uf/63V +0.1uf/63V in a place that existed only a 0.1uf/63V and often this is done with the wrong ground scheme ...FAIL !!!!!
5) Feedback chain ..small change in value there might change the all amplifier behavior ...DC blocking capacitors in various stages of the amplifier if beefed up can increase the low pass ability of the amplifier Can your speakers handle that ?
I would stick with original values, but specify 105 deg C rated Caps and check manufacturers specs for low ESR and long life.
Increasing your 10,000 uf for 12,000 uf won't cause any harm, but I would leave everything else alone.
You will only tell if your caps are snap in by looking at the underside of the PCB or Specs of the original caps. By doing this first, at least you can confirm your lead spacings.
Increasing your 10,000 uf for 12,000 uf won't cause any harm, but I would leave everything else alone.
You will only tell if your caps are snap in by looking at the underside of the PCB or Specs of the original caps. By doing this first, at least you can confirm your lead spacings.
Since the NAD 314 is a 35W/channel little amp and you won't play it LOUD for many hours, you can increase the main filtering caps in the power supplies by a bit without going unnecessary very high. The values above in bold are fine, just choose 105*C rated ones. For the other caps you better keep same capacitance values, because these have to do with voltage regulators. For these you choose, again, caps for higher voltage ratings (as long as they fit), and of 105*C are preferable for these NAD amps.
You also may check for broken/cold joints due to intense generated heat or poor soldering process, so typical of many amps produced in the 90s, see the picture below.
An externally hosted image should be here but it was not working when we last tested it.
I think it's too much. There might be other cheaper component suppliers in the EU (near you?) if you are going to order just a bunch of electrolytics.
I don't see NADs very often but most recent 306 had only a few electrolytics that where ok (preamp psu), in poweramp all were either completely defective or like 50% or less of foilvalue, main psu bulk ~50%, all electrolytics were 85 degrees Elna and just as in any Marantz amplifier those Elna's fail. The 306 played music, just like most Marantz full of failing Elna electrolytics do. No problem with 306 relais found, many bad solder joints/islands just like pic above and subsequent increased heat, pcb quality superior to Marantz.
What part was "Urban Legend" I've been repairing electronic equipment including many many amplifier repairs for 40+ years. Everything I stated I know to be true. If you look at the markings on any well labelled electrolytic you will clearly see the tolerance. And as I stated I'm not suggesting large changes in value and I do realize timing circuits require the right value or as close as you can get. I am certainly not in the habit of misleading anyone and resent the accusation.
Thank you to everyone for contributing on the topic, it seems caps are a controversial topic on the internet. Based on your suggestions, I have adjusted the original list and the final cost of all the caps is about 60 euro, and that's ok for my budget (Mouser is the best solution for me with their free shipping on orders over 50 euros).
One thing I am not sure about before I proceed is if the audio signal caps have also to be 105*C as all the Elna Silmic II caps I am about to buy are 85*C. Do you think that'll be a problem?
One thing I am not sure about before I proceed is if the audio signal caps have also to be 105*C as all the Elna Silmic II caps I am about to buy are 85*C. Do you think that'll be a problem?
It really depends on their physical location. If they are not near any heat generating devices (eg wire wound resistors, heatsinks etc) then 85 degrees should be fine. If they are and you are intent on using them, try manipulating their position away from the heat source,. Sometimes just leaning them away from the source is enough. Electrolytics don't like heat.
Cheers .
'
Cheers .
'
Ok, will do. Thanks everybody for the help, most likely I'll bother you again soon during the recapping process.
I just want to chime in on a zombie thread, I have a 314 with the Chinese caps throughout and I think essentially ALL the small caps are shot! I mean 4 ohm esr reading is about the best I found out of the entire unit! I found a cap in the preamp that measured 18 ohm....
Oddly enough the amp actually played but the main issue is a bad volume pot?
You sure the ESR meter is accurate and the caps are disconnected from the circuit as may be necessary for your type of tester? It's rare that an amp would work properly with such high ESR caps, regardless of where they were made.
They were all measured out of circuit.... The tester was testing the new caps with expected measurements?
I have replaced many caps in my 314 with very good results.
There are quiet a few el caps in the preamp section, direct in the signal path for DC blocking and bootstrapping. I recommend Elna Silmic for those. Very smooth sound.
I also changed the two main caps for Mundorfs with a slightly higher value with good subjektive results.
It is also worthwhile to change the caps in the regulator.
The Nad 304/314 is a very good amp. Just recapping with better parts will give you a marked improvement.
Good luck! (And report your results)
Thorsten
There are quiet a few el caps in the preamp section, direct in the signal path for DC blocking and bootstrapping. I recommend Elna Silmic for those. Very smooth sound.
I also changed the two main caps for Mundorfs with a slightly higher value with good subjektive results.
It is also worthwhile to change the caps in the regulator.
The Nad 304/314 is a very good amp. Just recapping with better parts will give you a marked improvement.
Good luck! (And report your results)
Thorsten
