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why a recap makes no difference

Discussion in 'Solid State' started by yotems, Feb 7, 2018.

  1. stereoguy70

    stereoguy70 Well-Known Member

    Messages:
    561
    Heatsink paste dries out over time and becomes hard as a rock. If you are in there, why wouldn't you? :crazy::rolleyes::dunno:
     
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  2. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Couldn't agree more :thumbsup:.
     
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  3. drumbum

    drumbum Super Member

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    1,207
    Because it doesn't have to be "wet" to do what it is intended to do, thermally couple a transistor to the heat sink.
    Can you show me the white paper on the study you personally have done?

    Every failure in vintage audio can be traced back to dried up paste.
     
  4. Eastham

    Eastham More Class-A than ever!

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    I think these arguments always fall down to *I believe X and because you believe Y, I am superior.* and both sides are guilty of this.
     
    Last edited: Feb 13, 2018
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  5. stereoguy70

    stereoguy70 Well-Known Member

    Messages:
    561
    White paper.......ha! That's a good one. :deal:

    If I'm working on a piece of gear that is more than 30 years old I replace it with new while I'm in there. Doesn't make sense not to. You're there and takes very little time. Most of the work I do for myself and they are usually full blown restorations. Take a few minutes to gain a few decades? Sure, I'll replace it.
     
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  6. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    On my big Onk amp, the power L/R power supply boards *edit* and the protection board(s) are a known problem area on them. There are 40 or so caps, all were not rated for the task or heat issues. So the amp will stop working after a while. Replacing the caps with better suited ones will make the amp work again. This is a very big difference.
    Note: this is being told in an obviousman sort of style, but yes old caps can cause this much of an issue.
     
    Last edited: Feb 13, 2018
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  7. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    I think this a great point tarior, recap for future reliability and if it also improves sound quality on a particular unit then this is a bonus :thumbsup:.
     
  8. tarior

    tarior Dirty pool, old man? Subscriber

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    Here's a true story, that probably means nothing. Shortly after opening my brick and mortar shop in '09, a local brought in his Marantz 2235 for service and evaluation.
    I told him that on top of cleaning all the switches and pots, clean/lube/dial-in the tuner, and replace all the dial lamps, that I recommended completely re-capping the regulated P/S and the power amp board, and shitcanning any known troublemaker semis while we were at it.
    He cried poor of course, so we ended up just doing the switches/pots, tuner, dial lamps, and maybe take care of a couple of VD-1212 diodes.
    Sure enough, he came back about a month later with a 1000uF cap in the P/S that had failed shorted.
     
  9. restorer-john

    restorer-john Addicted Member

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    Australia
    Excellent. Well done.

    (That Teapo/Flying Pigeon Chinese cap you stuck in the PS the month before did it's job...) ;)

    kidding.
     
  10. tarior

    tarior Dirty pool, old man? Subscriber

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    ^^LOL.
     
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  11. pustelniakr

    pustelniakr Silver Miner at Large Staff Member Super Mod Moderator Subscriber

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    Moderation Note:

    This thread has been cleaned up of a dust-up and its afterglow. No further disrespectful interactions will be tolerated here. Do not test me. Disagree if you will, but do it respectfully, and without interpersonal attacks. Various opinions are allowed, and respectful sharing of them is allowed.

    Rich P
     

     

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  12. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    I DO want to clarify though that doing a recap in hopes of "fixing" a unit that doesn't work is NOT the proper mind set.

    I am starting to see that philosophy showing up.
    Recapping WHILE FIXING is the proper way to think.


    I also cannot say that a recap will buy you 30 more years of service.
    Maybe, maybe not.
    Old parts are still getting older.
    I certainly hope the gear lasts until there is no one left alive to enjoy it.


    I have had a couple rebuilt units develop other issues after a recap, much later.

    I have found enough bad caps "hiding" in a unit I was repairing that now its almost automatic to replace e-caps while I'm digging around on a board.
    I keep a large stock of fresh caps around so it's silly not to install them while working on something nice.

    My own personal stash of nice gear is on the TO-DO list when I get time to recap them.
    Some of those pieces are not even TOTL.
    Some are just small little sweethearts that I enjoy using and since I can, I will.


    If you have a unit that you really enjoy, for what ever reason, and plan on keeping it around, a re-cap is not a dumb investment.

    A restored or re-capped unit value should not be compared to stock unit current value.
    Original condition is nice, but much like a nice original condition car, there are parts you don't want to keep using.
    e-caps, like tires, batteries, belts, hoses, all wear out.
     
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  13. steveUK

    steveUK AK Subscriber Subscriber

    Messages:
    488
    Location:
    Midlands, UK.
    Well there you go then, you wanted to do a 'full recap' when as was seen, just one cap needed changing. In my mind that's a clear point for the 'no need to do a full recap' camp.
     
  14. gslikker

    gslikker Super Member

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    2,114
    Location:
    Close to Alkmaar, Netherlands
    Hobbyists like me are ready to pick it up from the internet market, as soon as its owner decides to get rid of it when next part in it fails, to avoid a 3rd repair.:biggrin:
     
  15. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    C'mon Steve, no it isn't, and tarior didn't suggest a 'full recap' anyway. The PSU's in some units get really hot and all components there suffer, heat is the sworn enemy of electronics as the life & derating curves of any electrolytic capacitor shows.

    My personal opinion is that the "while you are in there, do them all" argument still trumps anything the 'one at a time' camp comes up with.
     
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  16. steveUK

    steveUK AK Subscriber Subscriber

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    I just don't get this 'while you're in there' argument. Having access to a set to perform switch and pot cleaning, alignment tweeks, even fault finding is not, in a great many cases, going to give you access to print side of boards, many of which need major dismantling for access to be gained. I differentiate strongly between having the top (and bottom) cover off a set - a situation that is easily obtained and allows a great many faults etc to be sorted out - and, major dismantling of assembles to gain further access. To me, the former is 'while you're in there' job, the latter is a 'BIG' job that goes to another level. Yep, I've sometimes done that when I've needed to change a component and had no choice (found by fault finding not a buckshot approach), but even then the process is often barely possible due to connecting wires limiting access etc etc. Again, not a welcome situation to be changing loads of Cs on that board. But each to there own. Like I say, me personally, I don't buy the while you're in there argument, it's a different level, and all part of a recap. Maybe living in the relatively mild, not hot, not cold temperatures of the UK I just don't come across so many duff Cs as you do, dunno.
     

     

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  17. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    It doesn't sound like you understand what is involved during fault finding and eventual reconditioning of a vintage piece. Whether it be a faultfinding/repair event or a 'recap' (I still hate that term), substantial disassembly is very often still required. Someone who is only prepared to take the top and bottom covers off a vintage piece - of the kind I am used to - is never going to do anything more than basic adjustments or superficial / cosmetic repairs. Which in the case of ~40 year old electronics is not going to be enough to keep it running faultlessly for long. The whole point of changing many parts while you have the unit in pieces - is so you don't have to do it all over again, as you would have to if you are/were in the 'one piece at a time' camp. If that doesn't make any sense to you, then I doubt that you understand electronic components or their failure modes, thus there is nothing further for me to discuss with you here.
    It may have escaped your notice that I too live in the UK. :)
     
    Last edited: Apr 9, 2018
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  18. tarior

    tarior Dirty pool, old man? Subscriber

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    I've never been to England, but the climate where I live, I think, is fairly similar. Wet, gray, and cloudy for much of the year, with nice, but generally not too hot summers.
     
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  19. pustelniakr

    pustelniakr Silver Miner at Large Staff Member Super Mod Moderator Subscriber

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    Generally, this kind of question is an attempt by a troll to start a controversy that he can enjoy watching. Granting the benefit of the doubt to the OP, here we go...

    Aluminum electrolytic capacitors function with a wet paste inside. The caps are sealed with a rubber seal. No seal is perfect. Over the years, the paste dries out. Some, even most, last a very long time, but the manufacturers generally specify a 25 year MTBF (mean time before failure). That does not mean that they will fail by this time, but that this is the average time of failure. Some last a lot longer, some last a lot shorter.

    Re-capping is NOT a good repair activity. Nor is it a good shot at sonic improvement. Electrolytic caps are among the very least stable parts in a design. If a designer set forth a design where you can hear the difference between electrolytic caps, he is not worth his salt. Such caps can cause degradation of sonic performance. At that time, replacing the bad cap(s) will/should restore performance. This is a repair operation, if done knowing that the parts replaced were bad. Once repair activities have restored proper operation, then recapping is a viable operation, aiming at longevity. Some sonic improvement is generally noted, but that is due to the elimination of an accumulation of very small contributions from drifted caps.

    Now, one can use functioning equipment that is beyond the expected lifespan of electrolytic caps. However, there is some risk to doing so. Some of them fail without noticeable affect to performance (bypass caps, and other minimal functions). All fail, over time, by drifting out of tolerance. Some fail by going open and simply ceasing to function, again, some causing noticeable affects, some without easily noted affects. On the other hand, some fail by becoming a short, or near short, in some cases taking out other components that are no longer available. Some cause catastrophic damage. Therefore, there is a variety of risk factors to using vintage gear with original electrolytic capacitors in them.

    You may choose to risk, or not to risk, but do so as an informed decision. Some, who are not technicians, successfully recap their own gear. Some cause serious damage. Depending on where it is, if you put one in backwards, or get a splash of solder where it does not belong, or damage circuit traces, it could be quite expensive, in damage, or in hiring competent help to repair it.

    My credentials: I am a design engineer with over 30 years experience. I have been working on this stuff since it was new. I know a bit about what I am speaking about. My current specialty is restoring vintage audio equipment of all types. Any vintage piece I restore for sale gets recapped.

    Enjoy,
    Rich P
     
    Last edited: Feb 14, 2018
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  20. steveUK

    steveUK AK Subscriber Subscriber

    Messages:
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    Location:
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    And it just sounds to me that you do not take in what I have written! I have been doing this (vintage audio/radio/TV repairs and restoration) for over 40 years. Many is the time I have disassembled sets in order to gain access to areas where faults are. I have completely opened up vintage radios, TVs, all manner of hifi pieces and even very complicated, electromechanically laden video recorders to perform 'open heart surgery'; complex setting up of video heads and guides etc to within microns. With lots of that stuff you just can't do that with just the top and bottom covers off! But on the other hand, and on many occasions, sets that were completely 'not working', no sound, have been readily repairable without major dismantling to such an extent that I would be tempted or even able to carry out a full recap. I hadn't noticed that you live in the UK, but in general most Audiokarma members are from the US where the trend for recapping is more popular.
     

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