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Post by pre65 on Apr 16, 2015 12:55:00 GMT
Perhaps some types of capacitor do last "for ever", but as I understand things electrolytic capacitors can "dry out" over a period of time even if the equipment is not used.
I also understand that if electrolytic capacitors are unused for a length of time they ideally need "reforming" before the equipment is reactivated.
To me a bulging capacitor is an explosion waiting to happen and I would replace such items promptly. 
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Post by MartinT on Apr 16, 2015 13:29:01 GMT
To me a bulging capacitor is an explosion waiting to happen and I would replace such items promptly. Yep, me too. |
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Post by Slinger on Apr 16, 2015 13:35:29 GMT
Here you go guys, how to calculate the lifetime of an Aluminium Electrolytic Capacitor  and to make it easier for you... Capacitor Lifetime Calculator(s)It also does "film" and "ceramic" caps. Yes, I know it's not "definitive" but you can now have fun desoldering all of your caps and reading the info on the sides so you can enter it into the calculators on that site, oh, and don't forget you'll need to know the ambient temperature of the operating environment too. Fun for all the family.   |
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Post by danielquinn on Apr 16, 2015 14:44:30 GMT
Perhaps some types of capacitor do last "for ever", but as I understand things electrolytic capacitors can "dry out" over a period of time even if the equipment is not used.
I also understand that if electrolytic capacitors are unused for a length of time they ideally need "reforming" before the equipment is reactivated.
To me a bulging capacitor is an explosion waiting to happen and I would replace such items promptly. Your claim to knowledge is " as I understand" thus the question is how do you understand perhaps you are simply repeating what you have read , which in turn was written by some one with a vested interest . A slingers post points out most treated kindly should last a bloody long time . However , what is most illuminating is that those who argue for a finite life span very rarely - if at all - advise chorently what age does to a capacitor and how this effects the SQ of your amp . |
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Post by MartinT on Apr 16, 2015 15:06:46 GMT
You can't estimate what age capacitors will last to any definitive degree as it depends on the environment, which often depends on the enclosure, air cooling and the place the device is run. I had a Sky HD box which was only about 4 years old when it expired. Upon opening it, nearly all the PSU electrolytics had blown their tops due to a combination of little to no cooling and poor grade caps in the first place. Replacing them all brought the box back to life again. I've also refurbished Leak & Rogers valve amps where the caps had lasted a good 25-30 years, which is very reasonable. Still needed changing, though.
Slinger, that calculator is very useful, thanks for the link.
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Post by pre65 on Apr 16, 2015 15:32:59 GMT
My stating "as I understand things" means exactly that.
If I make a statement it is "what I knew (or thought I knew) at that very moment in time".
Due to my thirst for knowledge, and my everyday (mostly) experiences of building bits and pieces for my system, my understanding of things can change. I've been into DIY hi-fi since I was a teenager, and now being in my 65 th year I hope I have some real experience of how things are. 
This does not, of course, imply that I'm always right. 
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Post by danielquinn on Apr 16, 2015 16:44:18 GMT
You are 65 well bugger me I thought you were 21.
With respect understanding is not y the same as empirical experience.
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Bonky
Rank: Trio
Posts: 156 
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Post by Bonky on Apr 16, 2015 16:50:02 GMT
Patrick of Sugdens was also rather scathing about audiophile mains plugs and leads and about the UK Hi-Fi press (with a few exceptions).
They apparently have a flourishing business but nearly all equipment is now for export only as the aforementioned UK press is 'too political'.
BW
Richard.
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Post by pre65 on Apr 16, 2015 17:03:55 GMT
You are 65 well bugger me I thought you were 21. With respect understanding is not y the same as empirical experience.
I have nothing to prove to you, or anyone else. I feel no need to convince anyone that my opinion is right. I contribute my pennyworth to the debate and let others decide whether they can benefit (or not) from what I have written.
I just wish that those who keep wittering on trying to make their opinion adopted as "right" would do the same.
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Post by MartinT on Apr 16, 2015 18:55:21 GMT
DQ, I don't know what point you're trying to make either.
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Post by gazjam on Apr 16, 2015 20:04:52 GMT
Decided to take manufacturers advice with my Densen Pre and get it recapped when it was back in Denmark for repair. Well..its over 25 years old, seems reasonable? Must say there IS a bit of paranoia over recapping. |
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Post by pre65 on Apr 16, 2015 20:08:33 GMT
Decided to take manufacturers advice with my Densen Pre and get it recapped when it was back in Denmark for repair. Well..its over 25 years old, seems reasonable? Must say there IS a bit of paranoia over recapping. |
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Post by Eduardo Wobblechops on Apr 16, 2015 20:41:47 GMT
Yep, did the same with the Kraken amp, seeing as it's 25 years old.
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Post by MartinT on Apr 16, 2015 20:58:35 GMT
I don't think you'll regret that, Gaz.
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Post by AlanS on Apr 17, 2015 8:00:01 GMT
DQ, I don't know what point you're trying to make either. I hope DQ does not mind me offering this consideration It is uncomfortable to read posts by someone who thinks they know but knows that they do not know. The "qualified" style of writing. It would be even more uncomfortable if spoken face to face. Let you yea be yea and your nay ne nay with maybe a traditional IMHO thrown in if uncertain What do you think of that concept? Whilst giving the same subject my attention. How does one alter the default font and size if one feels the need to do so?The web based version does not seem to offer that. I personally have no wish or need to BTW. |
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Post by MartinT on Apr 17, 2015 8:05:54 GMT
Let you yea be yea and your nay ne nay with maybe a traditional IMHO thrown in if uncertain What do you think of that concept? I'm all for it - BUT - it requires members to KNOW that they are writing bollox and not reply rather than cause confusion.
For me, an implied IMHO goes with any comment on a forum.
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Post by zippy on Apr 17, 2015 8:36:11 GMT
If you're going to worry about whether to turn it off or not, I suggest worrying about things you can't control so easily.
My Linn Kairn died because (I later found out) it had an internal battery soldered to the circuit board which leaked and destroyed the circuits. £1000 amp killed by a £5 battery.
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Post by danielquinn on Apr 17, 2015 8:54:26 GMT
You can understand something without having actual empirical experience .
I understand the consequences of calling a circuit judge a cock in court , I have not actually done it.
thus to say you understand "capacitors dry out" is not the same as saying in my experience I have seen capacitors dry out .
I also note once again that advocates of re-capping are a little hazy on its actual benefits and causal mechanisms at work which will give these benefits .
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Post by pre65 on Apr 17, 2015 9:19:46 GMT
Whilst researching the subject of "dried out" electrolytic capacitors I came upon a web page run by electronics and electrical engineering people.
The general consensus was that when trying to repair old equipment the best 1st step was to replace time expired electrolytic capacitors. And also the most common cause of power supply failure is dried up electrolytic filter capacitors. For instance when dealing with old arcade machines, the first step with a 30 year old malfunctioning monitor is to replace all (or most) of the caps before trying anything else. That step fixes many problems and makes most other issues tractable.
That is not my empirical evidence, but empirical evidence from people who do it for a living.
So, those who do not own vintage hi-fi might be safe for a few years.
This was (probably) the best advice given on the subject.
"With electrolytic caps you should always pass them through LCR meter for C & ESR check (unless you are using new caps from top-end supplier).
As long as you see that C & ESR match your requirement with some margin you can use this cap no matter how old is it. This way it's safe so reuse used caps too. Just validate them all."
*
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Post by danielquinn on Apr 17, 2015 9:51:40 GMT
A 30 year old fruit machine would be have been on for 15 hours plus 7 days a week and for 20 of them would have been in smoked filled room .
I also hope the caps in my power amp are manufactured better than those in a fruit machine .
the last point you makes reinforces the point I made in my first post , well made caps not constantly used with a small fraction of their tolerances will probably last a human life time .
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