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I'm getting a 20 year old NAD 2600A that is in good shape. I currently have an NAD 925THX 5 channel. My basic question about these solid-states...Do they loose their juice in the capacitors and such after a long period of time, and will this affect the performance??? I leave my 925THX on 24/7 with no signs of wear or problems....Bueller?
 

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Every electrolytic capacitor will age and finally stop working and its capacity will change over time, because its a temperature sensitive device and the electrolyte will dry out or leak over time. Most older amps will need their capacitors replaced, depending on age and make.

And 20 years is quite some time...
 

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I have read that hum is a possible side of bad caps (assuming it's not a ground loop.)


I would guess you might be able to measure the power supply voltage. But note that caps can hold a lot of energy and could be dangerous. And you have to know what you are doing, I think, to measure live (high) DC voltage in an amp. I once blew up a receiver trying to measure rail voltage when I accidently measured at the wrong point. So make sure you know what you are doing, and take all needed precautions.
 

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I once had a Sony V-FET amplifier that did 22 years of service during which it was powered up about 99% of the time. Its life (and several other things in the house) came to an end during a thunderstorm.


Subtle changes over time are not evident to most people most of the time. My occasional visits to audio dealers and home trials indicated that its performance near the end was about the same as many years earlier.
 

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It can but if it sounds fine it may not. How many 20+ year old TV's have you seen still working fine. Those big caps can last a long time or go bad under warranty just like all electronics.
 

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Is he still in prison? After the Vegas thing?


EDIT : Yep. Good place for him.
 

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As an aside, why has the misspelling of "lose" as "loose" become such an Internet meme? I do not recall this being so prevalent prior to, say, five years ago. It is almost as if many people have become infected w/ some kind of bio electronic virus.


AJ
 

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gurkey and MichaelJHuman have it right. In fact, the "guts" of all capacitors degrade over time, but electrolytics are particularly prone to losing charge capacity over time (and heat). When they lose enough to induce hum, other bad things are usually happening, so it's best not to wait that long. Before then, there will be a loss of charge storage that will reduce the amp's ability to handle peaks. You might not notice, especially as it's a gradual change, but you will likely notice when you replace them.


HTH - Don
 

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Besides the electrolytic capacitor's internal chemicals breaking down, this makes it more prone for the capacitor to short out..

When it shorts out, frequently more damage is done..


If > 10 years old, a good idea is to replace the capacitors.

Another suggestion is when powering up the older product use a variac and apply the AC voltage slowly in steps..


Just my $0.02...
 

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Quote:
Originally Posted by gferrell /forum/post/19636243


It can but if it sounds fine it may not. How many 20+ year old TV's have you seen still working fine. Those big caps can last a long time or go bad under warranty just like all electronics.

RCA FLR 2522 Colortrak table top TV. It did solo duty for 20 years plus news, weather, and talking heads for the past 5 years. I won't even guess how many hours on it with one minor audio repair about 19 years ago.


It also serves as a stand to position the center speaker at the right spot behind the projection screen when doing the HT thing.
 

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It is just about impossible to design electrolytic capacitors to last longer than 10 years within specs (this doesn't mean the amp will suddenly stop working).


Due to the nature of audio amp loads the bulk storage caps are often not stressed for most of there operation thus even though they are no longer within spec the drop in capacitance often doesn't greatly effect performance.


I have seen a few amps last 15 to 20 years before the caps gave problems but at the same time I have seen a number of newer AVR's which have died due to cap failures after 2-3 years.


IMO it certainly doesn't hurt to replace the electrolytic caps every 10 years and by doing so you will most likely avoid further problems such as leaked electrolyte which is corrosive and damages near by components and circuit boards.
 

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I have always found this an interesting subject that gets a lot of conjecture applied. If you go the web page below pay attention to pages 15 and 16 of the document. There is absolutely no reason in a properly designed power supply caps cannot last for many decades. I have worked in industrial electronics for 25 years and have made many repairs to equipment that is 30 to 40 years plus old that have electrolytics that are still going strong.


electrochem.cwru.edu/encycl/misc/c04-appguide.pdf



If you read this paper you will see that caps tend to fail early on and catastrophically (infant mortality). Or, they tend to fail very slowly based on operating temperature and operating time.
 

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Quote:
Originally Posted by Just cruising /forum/post/19643045


I have always found this an interesting subject that gets a lot of conjecture applied. If you go the web page below pay attention to pages 15 and 16 of the document. There is absolutely no reason in a properly designed power supply caps cannot last for many decades. I have worked in industrial electronics for 25 years and have made many repairs to equipment that is 30 to 40 years plus old that have electrolytics that are still going strong.


electrochem.cwru.edu/encycl/misc/c04-appguide.pdf



If you read this paper you will see that caps tend to fail early on and catastrophically (infant mortality). Or, they tend to fail very slowly based on operating temperature and operating time.

So maybe you should be selling reservoir capacitor insurance. If many people think they die young, and you think they last 30+years, I think you can make money.


Simple economics says that when people overvalue something, there's money to be made
In they case, they will overvalue your insurance. I suggest charging $50 for 10 years of cap insurance. It should be almost all profit!



Provided people don't 'loose' their capacitors (as opposed to losing them)
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/19643438


So maybe you should be selling reservoir capacitor insurance. If many people think they die young, and you think they last 30+years, I think you can make money.


Simple economics says that when people overvalue something, there's money to be made
In they case, they will overvalue your insurance. I suggest charging $50 for 10 years of cap insurance. It should be almost all profit!



Provided people don't 'loose' their capacitors (as opposed to losing them)

That is the problem they don't fail often enough to have a market!
 

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I have dealt with various capacitors for decades. There's a reason the typical electrolytic tolerance is +50%/-10%... Mainly so at mid-life, or after typical qual/burn-in testing, it will measure at least the rated value.


HV especially electro's tend to pin-hole the dielectric, a slow degradation that ends up with a positive feedback situation at EOL (end of life) causing rapid and often catastrophic failure. There are so many variables during manufacture, installation and operation that it's hard to predict a capacitor's (or anything/one's) life with certainty. Of course we see the bathtub curve, with most failures at the beginning and end of life, but in my experience (and perhaps no one else's) the floor of the tub appears a lot rockier when electrolytics are measured.


YMMV - Don
 

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Does it help lifespan to use multiple lower voltage rated caps rather than one single high voltage cap per rail do you think?
 

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Quote:
Originally Posted by NeveSSL
I'm pretty sure you missed his point.



Brandon
No, I don't think I did. I just think it was kind of a silly response to a technical answer.
If you read the white papers and pay attention to the section on the life expectancy, the life of a cap is based on the operating temperature and the life hour rating temperature. For every 10 degrees that the operating temperature is lowered the life doubles. So a high quality cap that is rated for 105C that operates at a reasonable temp, say 50C will easily last hundreds of thousands of hours. The operating temp of the caps is based on ripple currents. The ripple current on the power supply for an AB amp is directly proportional to the power output to the speakers. In most listening most people only use a fraction of the rated power. Therefore the supply and caps in most cases are not working anywhere near their limits. Of course this is a bit different for an A class amp but still they should last a very long time on a well design power supply. I don't know, do a poll. How many people on this site have had to have their caps replaced in their amps and receivers? I have 4 receivers in my home. The oldest is just over 30 years old and the newest is about 10years old. I have 3 power amps. The oldest is 16 years old and the newest in a year old. No problems yet, all still going strong. Of course I always make sure that my equipment is well ventilated.
 
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