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its been recapped - Why do we need to replace the caps?

Discussion in 'Pro Audio Equipment' started by audiokid, Jan 11, 2014.

  1. audiokid

    audiokid Staff

    Forgive me for such a question but why does everything always end up needing to be "recapped"
     
  2. dvdhawk

    dvdhawk Well-Known Member

    This link from Harvard is as good as any:
     
  3. djmukilteo

    djmukilteo Well-Known Member

    It's not a stupid question, it's a stupid approach. But it's easy and cheap to do. And you know how important it is to have something "modded" these days. I think most of these people just want to say that..."oh this was modded" like that automatically makes it somewhat more likely to create you a hit record from your bedroom...LOL
    From an electronics POV it may or may not be the problem or make an improvement, but nobody bother's to actually determine that sort of reality anymore via troubleshooting or measurements...and like I said it's a cheap thing to do. Anyone with a screwdriver, soldering iron and a Mouser account can do it. Sometimes it works, sometimes it doesn't. But hey you can say it's been recapped!
    OTOH caps are one of the most common components to fail in circuit especially electrolytic's and the nice thing is they are easily replaced and still available, unlike a lot of other components. Many times a recap fixes all sorts of problems. If resistors were as unreliable as caps everybody would replace those too, cuz they're cheap and easy to replace and many people do!....LOL
    So to some degree it's a no brain'r approach...you don't need to know how or why you can just do it and sometimes it works and you didn't need to know.
    Of course there are better quality/spec caps these days too, so there can be cases made where the age and sonic condition of a particular piece of gear might in fact see some sonic improvement. It's easier to just make a blanket statement like "recap it" and see what happens. But many times doing that can change the sonic characteristics completely and you're left with an inferior sound from the original.
     
  4. mberry593

    mberry593 Active Member

    For the last few years I have picked up some extra money on the side doing freelance maintenance at two TV facilities. I can tell you from my experiences that the two biggest problems in broadcast equipment are the switches and the aluminum electrolytics. I usually ended up working on (video) monitors because no one else wanted to work on them -- the high voltage attracts lots of filth. I turned it into a game. When I got a bad monitor, I tried to predict what capacitor had failed. After a few years, I got fairly good at it with Sony monitors. I could usually repair a monitor in less than 15 minutes.

    Another person who did this had an entirely different approach. He worked on DVC Pro tape machines. He never tried to figure out what was wrong beyond isolating it to a circuit board. He swapped out boards, did an alignment and quickly returned the machines to service. After that, he then replaced all of the (usually surface-mount) capacitors on the bad board. He reasoned that they were all the same age and if one failed, the rest were likely to go soon too.

    So, pick your philosophy, but failing electrolytics are great for the economy....they are job creators! Politicians should be celebrating aluminum electrolytics.
     
  5. JohnTodd

    JohnTodd Well-Known Member

    I'm no electronics guy, but I know from experience that replacing caps on some amps and some guitars will "perk" them back up again.

    Also, on some amps and some guitars, a better quality cap is an upgrade. The manufacturer may have spent $.000000000002 on a cap, so you spend $2.00 on one to replace it and BAM! Suddenly the guitar or amp sounds like it costs a lot more.
     

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