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  1. #1

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    Pro Foto Acute B recycle time is now 12 seconds!!

    I have a little Profoto Acute B 600 generator, it's slowly in it's death throws I believe as the power switch (with Max, 4 and 2 as levels) only works on Max and 2 now and the recycle time has gone from quite fast (1 or 2 seconds depending on power) to 12 seconds.

    There is so little information I could find using google so I'm reaching out here... looks like I have no choice but repair or a new one (so expensive!!!).

    Anyone have any ideas on these kind of problems?

    Funny thing is, once a flash is used, I can toggle the power switch and it charges instantly...!?
    www.detunephotography.com

  2. #2
    TheFlyingCamera's Avatar
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    Sounds like you're looking at a pricey repair. Don't know the cause, but that's definitely not normal behavior. The Profotos are nice enough that they're worth repairing at least once, unless the repair bill comes out to the replacement cost. Look them up on ebay to see what a used unit runs.

  3. #3

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    From your description that it recycles quickly once it's used, it is probably the main capacitor.
    That's the one that provides the power to the flashtube. When they age they become hard to charge but once they've been recycled a couple of times they work properly(sound familiar) This is common with electronic flash both portable and studio.
    Heavily sedated for your protection.

  4. #4

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    dam, yeah I figured it might be the capacitor, really it's such a tiny little box but it is amazing when it's working... just horribly priced.. and this sounds like a costly repair too.
    www.detunephotography.com

  5. #5

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    Leave it on for a coupe of hours, that will get the capacitor in a better shape.
    Do this at least once every month untill you see an improvement.
    Replacing capacitors is not a big deal for a repairman, getting the replacement can be if it is an off-one.
    Contact the manufacturer.

    Don't do the replacement your self: even after a full discharge quite a few Volts are left in them.

  6. #6
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    Quote Originally Posted by detune View Post
    dam, yeah I figured it might be the capacitor, really it's such a tiny little box but it is amazing when it's working... just horribly priced.. and this sounds like a costly repair too.
    High value capacitors aren't cheap, but they're not exactly unobtainium either - it ought to be a relatively inexpensive repair I'd have thought.

    If for some reason a suitable replacement capacitor wasn't available, it is possible to reform caps with a fair degree of success relatively easily - I believe the military used to actually have dedicated capacitor reforming units which you can pick up at Ham events or military surplus, but all you really need is a variac. Like I say, I think it's highly unlikely to be necessary in this case, but it's rather common in my other hobby (classic computer equipment.)

    If you know a friendly amateur radio enthusiast, this is repair they could probably do for you easily enough.



    If the cap is on the way out though, it is best to get it fixed. Occasionally they can fail catastrophically (i.e. explosively) throwing corrosive electrolyte all over the rest of the board, turning what was a cheap repair into a pain-in-the-neck cleanup operation.

    (I remember once at work we were working on some experimental communications hardware and had a big demo to senior management who were flying in the following morning; of course, just as we're doing the final checks on the demo kit the night before, a cap in one of the units decides it's going to explode in a really quite dramatic way. A late night followed... The demo effect is a wonderful thing!)
    Another day goes under; a little bourbon will take the strain...

  7. #7
    resummerfield's Avatar
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    Quote Originally Posted by tim_walls View Post
    ...... it is possible to reform caps with a fair degree of success relatively easily.....
    I've always heard that a strobe that fails to recycle promptly needs to have its capacitors "reformed". I think this "reforming" can be accomplished by turning the strobe on and letting it "idle" for a day or so, with an occasional full discharge flash. But in my personal experience, I have not been very successful in "reforming" capacitors to get recycle time back to new specs.

    Does anyone know the correct procedure for "reforming" capacitors?

  8. #8

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    well I'll hopefully hear back next Monday about it and I'll post up here about the repair (cost and reason) so we can all learn from my bad luck :P There were no explosions, just a sudden slowness in charging and sometimes the ready beep would be a BEEEEEEEEEEEEEp instead of bip..!
    www.detunephotography.com

  9. #9
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    Quote Originally Posted by resummerfield View Post
    I've always heard that a strobe that fails to recycle promptly needs to have its capacitors "reformed". I think this "reforming" can be accomplished by turning the strobe on and letting it "idle" for a day or so, with an occasional full discharge flash. But in my personal experience, I have not been very successful in "reforming" capacitors to get recycle time back to new specs.

    Does anyone know the correct procedure for "reforming" capacitors?
    Basically it boils down to connecting the cap up to a DC supply at its voltage rating, with a nice hefty current-limiting resistor in series. An unhealthy capacitor will leak current - in the worst case appear as a dead short - without the resistor in place this can lead to catastrophic failure.

    With a CL resistor in place on the other hand, the current is limited to a safe level, allowing the oxide layer on the electrode to slowly re-form without the capacitor exploding.

    The process may take hours or even days; you can tell whether or not it's finished by measuring the voltage drop across the resistor - a healthy capacitor will be leaking very little current, and so there will be little if any drop across the resistor.


    It should be said though that reforming capacitors is normally only necessary if they've been in storage for a long time. In 'normal service' the small leakage current they exhibit normally is enough to keep the oxide layet healthy; it's normally only when they've been unplugged for a while that the layer deteriorates.
    Another day goes under; a little bourbon will take the strain...

  10. #10
    resummerfield's Avatar
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    Thanks, Tim.

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