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Electrolytic capacitors

I have learned from this web-site that the life span of the electrolytic cap is within 5 to 10 years. I also heard some testimonials that some SS amps or receivers last over 10 or 20 years without a hick-cup. I am confused and scared since I am looking to buy some discontinued but brand new in factory sealed box amps and a processor ( around 4 to 5 years old). Being few years old and in storage but never been used at all, would the 5 to 10 years rule of thumb of the electrolytic cap still apply?
andrewdoan
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shadorne
7,477 posts
 
You need to reform the caps before powering up (to reduce the risk of them blowing up when powered up the first time)....after four years of storage this is a significant risk.

These kind of caps tend to dry out after many years - so yes, in theory the fact that they are four years old will reduce the life expectancy of the device - even if it is new in the box unused - the good news is the re-capping is EASY!!
andrewdoan OP
223 posts
 
In another thread, there is some suggestion about the Variacs to power up SS amps that have been in storage for a while. Would some one please tell me how to find out about the value of the electrolytic caps inside the amps ? I was lucky with my last purchase, the BAT VK20 which is new in the sealed box made in 2001. The unit did not blow up in my face and works as new. Recently, I have ordered some 4/5 years old new in box Parasound amps and processor for my HT and now I wonder if I am pushing my luck. It seems the odd is against buying used or discontinued gear but why there are so many buy/sale transactions ? Are people aware of this "bang explosion" electrolytic caps deal ?
elevick
2,636 posts
 
Get the seller to power it up for 24 hours. If they want to pay to have it done on a variac, great. If they want to gamble, that's on them too.
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shadorne
7,477 posts
 
Get the seller to power it up for 24 hours. If they want to pay to have it done on a variac, great. If they want to gamble, that's on them too.

Great idea if you can get this done for you....but then it is no longer a factory sealed box - so the seller may not be willing to break the seals on the packaging.
aball
2,018 posts
 
4 or 5 years is no problem. 8 or 9 of zero use is starting to get to where you should worry a little. Over 20 you need to consider replacement. This is my experience as an EE.

There are thousands of capacitors for sale at Newark and Digikey that have been on the shelf for years, waiting to be sold and no one uses a variac when they power them up for the first time. I have powered up MANY converters and power supplies in my lab that sat for at least a decade and there was never any issue. You are worrying way too much about this. Just enjoy the music.

Arthur
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