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Japanese brands are renowned for having a very reliable electrolyte formula. Dell sourced some capacitors made in Taiwan using a stolen copy of the formulae and

Japanese brands are renowned for having a very reliable electrolyte formula. Dell sourced some capacitors made in Taiwan using a stolen copy of the formulae and it cost them massively. https://www.theguardian.com/technology/blog/2010/jun/29/dell-problems-capacitors https://www.theguardian.com/technology/blog/2010/jun/29/dell...

goldcd 5y ago
Wasn't just Dell - https://en.wikipedia.org/wiki/Capacitor_plague#:~:text=The%20capacitor%20plague%20was%20a,generation%2C%20often%20rupturing%20the%20case https://en.wikipedia.org/wiki/Capacitor_plague#:~:text=The%2... Although even putting this aside, capacitors don't seem to age well - anybody interested in 80s/90s electronics and gaming, will be aware that they should check boards before plugging them in, and if in doubt, but a 're-capping' kit
- galangalalgol 5y ago
  An old school RF engineer told me you can put an incandescent light bulb in the enclosure for a few hours periodically to bake out the moisture and they are fine again. I was going to re-cap a 60s heathkit tube stereo and he asked me why I thought they had been fine for half a century but suddenly might blow any second? If you used the tube amps regularly the heat from the tubes kept the caps good.
  - zokier 5y ago
    That's... not how things work. Generally electrolytic capacitor lifetime halves for every 10°C temperature increase. Ref: http://www.rubycon.co.jp/en/products/alumi/pdf/life.pdf http://www.rubycon.co.jp/en/products/alumi/pdf/life.pdf https://www.digikey.dk/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_PredictingLifeTemp.pdf https://www.digikey.dk/Web%20Export/Supplier%20Content/CDE_3... https://jianghai-europe.com/wp-content/uploads/Jianghai-Europe-E-Cap-Lifetime-Estimation-long-AAL-2018-09-18.pdf https://jianghai-europe.com/wp-content/uploads/Jianghai-Euro... (page 9)
    - deleted 5y ago
      [deleted]
    - galangalalgol 5y ago
      Is it possible those old caps used something else? He said the electrolyte was hygroscopic.
      - formerly_proven 5y ago
        Yes. Capacitors before around ~1990 used organic solvents and were, generally speaking, very reliable. Capacitors since then switched to water-based electrolytes, which are 1) much more aggressive which 2) leads to circuit board damage if they leak and 3) if done improperly has very bad longevity. Capacitor plague is basically all of these downsides combined in one sweet package: capacitors that fail quickly, and do so while leaking acid all over your circuit boards, acid which is strong enough to eat through solder resist, copper, fiberglass and even goes into IC packages, damaging them invisibly. Old-timey capacitors with organic electrolytes are still available for applications that need reliability more than the best ESR or highest density, but they're kinda rare and expensive.
      - dfox 5y ago
        I would not be surprised if this trick was meant for early encapsulated foil capacitors. These were encapsulated in various semi-natural resins of not exactly known or repeatable properties (usually the intention was that the resin is hygroscopic, but often it was also porous and prone to cracking with aging). Edit: then there is “RIFA plague”, which shows that you can get same issue even with better engineered encapsulation material.
    - tinco 5y ago
      Audio systems are usually powered off for most of the time. If it's on a couple hours a week, that 10 degrees increase might "boil off" that moisture while not making a dent in the capacitor lifetime.
      - TylerE 5y ago
  - hakfoo 5y ago
    Aside from outright "it popped and oozed all over the place" failure, you've got drift in specs-- the original design expected 100 +/- 10uF, and you're now at 60 or 125uF, with a different equivalent-series-resistance and leakage than the part had when new. In a lot of cases, this won't directly cause explosion, but it might make for a noisier signal down the line. I've replaced the electrolytic caps in two different stereo recievers and one amplifier, all from the 1977-1980 era. Only one of the three had noticable difference in sound quality, but it was the one that had clearly been abused over the years (failing power switch that arced and sputtered, absolutely filthy and blown bulbs when I got it)

goldcd 5y ago

Wasn't just Dell - https://en.wikipedia.org/wiki/Capacitor_plague#:~:text=The%20capacitor%20plague%20was%20a,generation%2C%20often%20rupturing%20the%20case https://en.wikipedia.org/wiki/Capacitor_plague#:~:text=The%2... Although even putting this aside, capacitors don't seem to age well - anybody interested in 80s/90s electronics and gaming, will be aware that they should check boards before plugging them in, and if in doubt, but a 're-capping' kit

galangalalgol 5y ago
An old school RF engineer told me you can put an incandescent light bulb in the enclosure for a few hours periodically to bake out the moisture and they are fine again. I was going to re-cap a 60s heathkit tube stereo and he asked me why I thought they had been fine for half a century but suddenly might blow any second? If you used the tube amps regularly the heat from the tubes kept the caps good.
- zokier 5y ago
  That's... not how things work. Generally electrolytic capacitor lifetime halves for every 10°C temperature increase. Ref: http://www.rubycon.co.jp/en/products/alumi/pdf/life.pdf http://www.rubycon.co.jp/en/products/alumi/pdf/life.pdf https://www.digikey.dk/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_PredictingLifeTemp.pdf https://www.digikey.dk/Web%20Export/Supplier%20Content/CDE_3... https://jianghai-europe.com/wp-content/uploads/Jianghai-Europe-E-Cap-Lifetime-Estimation-long-AAL-2018-09-18.pdf https://jianghai-europe.com/wp-content/uploads/Jianghai-Euro... (page 9)
  - deleted 5y ago
    [deleted]
  - galangalalgol 5y ago
    Is it possible those old caps used something else? He said the electrolyte was hygroscopic.
    - formerly_proven 5y ago
      Yes. Capacitors before around ~1990 used organic solvents and were, generally speaking, very reliable. Capacitors since then switched to water-based electrolytes, which are 1) much more aggressive which 2) leads to circuit board damage if they leak and 3) if done improperly has very bad longevity. Capacitor plague is basically all of these downsides combined in one sweet package: capacitors that fail quickly, and do so while leaking acid all over your circuit boards, acid which is strong enough to eat through solder resist, copper, fiberglass and even goes into IC packages, damaging them invisibly. Old-timey capacitors with organic electrolytes are still available for applications that need reliability more than the best ESR or highest density, but they're kinda rare and expensive.
    - dfox 5y ago
      I would not be surprised if this trick was meant for early encapsulated foil capacitors. These were encapsulated in various semi-natural resins of not exactly known or repeatable properties (usually the intention was that the resin is hygroscopic, but often it was also porous and prone to cracking with aging). Edit: then there is “RIFA plague”, which shows that you can get same issue even with better engineered encapsulation material.
  - tinco 5y ago
    Audio systems are usually powered off for most of the time. If it's on a couple hours a week, that 10 degrees increase might "boil off" that moisture while not making a dent in the capacitor lifetime.
    - TylerE 5y ago
- hakfoo 5y ago
  Aside from outright "it popped and oozed all over the place" failure, you've got drift in specs-- the original design expected 100 +/- 10uF, and you're now at 60 or 125uF, with a different equivalent-series-resistance and leakage than the part had when new. In a lot of cases, this won't directly cause explosion, but it might make for a noisier signal down the line. I've replaced the electrolytic caps in two different stereo recievers and one amplifier, all from the 1977-1980 era. Only one of the three had noticable difference in sound quality, but it was the one that had clearly been abused over the years (failing power switch that arced and sputtered, absolutely filthy and blown bulbs when I got it)