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Discussion Starter · #1 ·
I know these gradually wear out, but is there a rule of when they should be replaced, like once every ten years (for example)?
 

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Their chemical composition dries out..

Then they can short out and blow causing other damage..

10-12 years is a standard life, but if the climate is one of high humidity this can accelerate the drying out process...


Just my $0.02..
 

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Quote:
Originally Posted by dclark
I know these gradually wear out, but is there a rule of when they should be replaced, like once every ten years (for example)?
not trying to be a smart a',,,replace when they break !
 

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I heard, if they develop a hum, that they did not have before under the same conditions, that could be from bad caps. No idea if that's an old wive's tale, but seems I heard it from reliable sources.
 

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Michael, absolutely true. I just repaired a guitar amp that had a huge hum, the power supply cap on one of the rails opened up, and stopped doing its job.

Some caps will last 50 years, some 5. I would not fix something that was not broken. Most will go 15 years or so before issues, and then replacing the whole unit is the better option in a lot of cases.

Also, there is a lot of crap caps that were/are let loose from over seas. Some of those only went a year before they let go.
 

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Discussion Starter · #6 ·
Quote:
Originally Posted by M Code
Their chemical composition dries out..

Then they can short out and blow causing other damage..

10-12 years is a standard life, but if the climate is one of high humidity this can accelerate the drying out process...


Just my $0.02..
Do you mean areas with low humidity cause them to dry out? I live in the high desert, low humidity, and have been making daily use of a an Outlaw 750 power amp for the last 10 years or so. I also recently got a '81 Realistic 2100D receiver that I am wonder about capping as well.
 

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I have a few different amps, the oldest being a Denon POA-2400 from 1989. None of them have needed re-capping yet. Even some older amps that I have given or sold to friends are still functioning fine. Of course there are many variables, how hot the equipment gets, how often, and how long it gets used, etc.


I also have some speakers from 1989. I was convinced to rebuild the crossovers on them in 2006,. I was told the values would be way out of spec at 17 years old (caps and resisters), and that modern polypropylene caps sound much better than the original electrolytics from the factory. I couldn't tell any difference when I was done, so I measured all the caps and resistors. They were all still within spec.


Fix it when it breaks.
 

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Hum is good first sign that a cap is going. I have some receivers from the 70's that are still fine so if you don't have a hum problem I would no worry.
 

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^^^ Hum, and/or "popcorn" noise, sort of a crackling noise when coupling caps start going bad.


Caps can be reconditioned, but if they are really going bad it's best to replace them before other damage occurs. That said, I would not replace them unless they really needed it. The only time I have replaced caps when I couldn't a problem was in an amp with big power caps that had lost half their value or more; the bass got better after replacement (no other measurable or audible changes).
 
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