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  1. #11
    Leigh B's Avatar
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    Quote Originally Posted by tkamiya View Post
    Electrolytic capacitor is made of thin aluminum foil and wet paper. It's not sealed completely either.
    There is no paper in an electrolytic capacitor. The electrolyte is a very thin layer, like a film.

    They are completely sealed. That's why they have a pressure-relief plug or can scoring.
    That's also why they explode when they fail.

    The manufacturers recommend that the caps be re-formed (see post #3) if they've not been powered up for six months.

    Novatron recommends operating their packs at least 30 minutes every four weeks.
    They recommend re-forming the capacitors if the pack has sat unused for longer periods.

    - Leigh
    Last edited by Leigh B; 07-18-2012 at 08:58 PM. Click to view previous post history.
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  2. #12

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    If you want me to be completely accurate and complete, I can. For the purpose and intent of this discussion, it wasn't necessary for me to mention it isn't always paper. If you take apart mylar or film capacitors, they are indeed film. I *think* (I'm guessing here), in order to achieve the capacity electrolytic capacitors achieve given the same and the surface area, it is necessary to have a material with high dialectic constant in between plates. I think that's why the fibrous structure and gel/fluid.

    Electrolytic capacitor has a fibrous structure between foils soaked with electrolytic fluid/gell. If you take apart really old ones, they are actually paper. I haven't taken one apart in the last 30 years so I don't know what they are made of now. Tantalum capacitors are sealed. Regular electrolytic ones aren't. I've seen plenty of them leak, actually. They also do dry up without exploding given long enough time.

    If certain equipment comes with an instructions to do certain things, I certainly recommend you follow them. Smaller flash units I have do not have such instructions and neither as many many equipment I have hear that contain electrolytic capacitors. Absence of specific instructions, I don't do anything but use it and fix it or replace it when it breaks.

    Anyway, have a nice day.
    Develop, stop, fix.... wait.... where's my film?

  3. #13
    Leigh B's Avatar
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    tkamiya,

    While the technology you describe might have been in use 50 years ago, it's definitely not used today.

    Modern electrolytic caps DO NOT use paper, and they ARE sealed.

    This is a pointless discussion since the recommendations of the manufacturers are clearly stated.

    Capacitors in photographic flash units behave quite differently than those in regular equipment because they sit unpowered
    for extended periods of time, then are expected to operate as low-impedance sources intermittently.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  4. #14

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    Quote Originally Posted by tkamiya View Post
    I don't have much experience with professional flash units but I do have lots of experience with electrolytic capacitors being an electronics hobbyist and a formerly active amateur radio operator. I used to love older equipment.

    It is commonly said that unused, electrolytic capacitors dry up and die. I actually have NOT found this to be true.

    They seem to degrade used or not and eventually die. When they are used right up to the capacity, they tend to have shorter life. When used in higher temperature, they seem to die sooner. Conservatively rated and used, they tend to last longer. Of course, being a consumer, we don't have a choice on design parameters....

    I personally don't worry about this. Use them when I need them. When they die, I just replace them.
    Electronics has been a long time hobby of mine as well. When it comes to capacitors "leaking" liquid, they are probably refering to the old waxed caps of the tube days of yesteryear that were built like batteries n were wet.

    Modern caps are built much better n leak alot less due to metal casings n special directional expansion slots to keep em from exploding like bombs n catch fire as they once did.

    I had an old studio 4 head Balcor that used 16 huge caps the size of dry cells. When that thing finally went the tops of a few caps blew n sounded like a welder with a stuck rod for a couple of seconds, that high voltage hummmmmm, then POP!.. lights out in the building. The stech of electronic smoke like a florecent balast cooking n the main entrance circuit breaker checked out. When I opened the box to see what the problem was several months later, I followed standard proceedure handeling caps, discharging the remaining uncooked ones, I noticed they were still fiully charged. Balcor diagrams showed a slow bleed circuit but it must be a very slow bleed. So don't think your caps are fully discharged because it has been sitting around for a long time, they do take time to bleed off.

    I fired up an old potato masher Sunpack 611 after not using it for 35 years. It whistled as it normally does then settled in to the usual beep beep beep so, out of habbit, I fired it at full power a few times. No problem at all n I have been using it regularly for the past year, even made a battery replacement using a sealed lead acid 6V battery.

    .
    Anyone can make a Digital print, but only a photographer can make a photograph.

  5. #15
    Leigh B's Avatar
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    Quote Originally Posted by paul ron View Post
    ...built much better n leak a lot less...
    Do you mean "... and leak a lot less..."?

    This is not Twitter.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  6. #16
    DWThomas's Avatar
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    I too believe modern electrolytic caps no longer use paper, but we must remember some of these units we're talking about are approximately sixty years old!

    Circa 1975, a tech where I worked managed to wire a high current, low voltage power supply with a bunch of 2000 uF filter caps installed with their polarity reversed. When he threw the switch, there was a loud ka-PLOW! Amidst the smoke, bits of aluminum foil were fluttering around the lab almost up to the ceiling -- sort of like the chaff to fool radar in WWII. Wish I had a photo of the look on his face; no doubt one of his more memorable learning experiences.

  7. #17
    Leigh B's Avatar
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    Quote Originally Posted by DWThomas View Post
    ...but we must remember some of these units we're talking about are approximately sixty years old!
    Yeah, I'll go along with that. Perhaps not 60, but certainly 40 or more.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  8. #18

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    Quote Originally Posted by Leigh B View Post
    Do you mean "... and leak a lot less..."?

    This is not Twitter.

    - Leigh
    Ur bng a hatr.

  9. #19

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    Quote Originally Posted by Leigh B View Post
    Do you mean "... and leak a lot less..."?

    This is not Twitter.

    - Leigh
    N what's a twitter?

    I didn't realize we were being graded for speeling n grammor. uisn't content more impertent? It seams you new what I meat, so why plost uch a upid remak that has noting to do with the tipic at hand?

    Get a life!

    For a better understanding of caps, read this....
    http://en.wikipedia.org/wiki/Electrolytic_capacitor
    Anyone can make a Digital print, but only a photographer can make a photograph.

  10. #20

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    All electrolytic caps, by definition, use very thin (a few molecules thick)oxide layer as a dielectric. Capacitors using paper as a dielectric are (oddly enough) called paper capacitors. Caps are (and have historically been) the least reliable component in electronics. Period. One would do well to try and keep them happy.

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