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  1. #1
    hoffy's Avatar
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    Using a live hotshoe on a cold fitting?

    Howdy,

    As part of a Minolta XE kit I was given, I received a Vivitar 283 flashgun. I decided to give it a try on my Koni-Omega, so I slide it onto the cold shoe, connected the flash via the sync port and gave it a try.

    All worked fine (except for my technique), until I slide the flash off the unit. I turned it off, released the latch and slide it off. As I did, the unit flashed (obviously I had closed the connection. Even though the shoe on the Koni is dead, it is still metal). Will this kind of shorting cause drama? Would I be best insulating the connectors on the flash before doing this again?

    Cheers

  2. #2
    Ian Grant's Avatar
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    Some flashguns the shoe isn't live when the cords in use, not sure on the Vivitars, but that was how older Sunpacks used to work. You may have to insulate the flash or the Omega hot shoe if it's live all the time. Or there are hotshoe adaptors for guns with no cord, they isolate the flash foot from the hotshoe.

    Ian

  3. #3
    Steve Smith's Avatar
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    If you had the lead plugged into the 283 then the hotshoe centre connection should be disconnected, if it was not, the flash would not work when fitted onto an all metal shoe. Most likely you pressed the test button or temporarily dislodged the lead whilst removing the flash.


    Steve.

  4. #4
    hoffy's Avatar
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    Thanks. I had removed the cable before removing the flash. I also know I hadn't discharged the gun after switching it off. That would explain it.

    Just a side note, how reliable are the electronics on these flashes? Could I expect decent service out of it (I think the flash is definitely pre 1980, not the modern version)

  5. #5
    Ian Grant's Avatar
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    Usually fairly good, it's the capacitors that tend to go first, but I have quite a few older flashes from the 70's that work perfectly.

    Ian

  6. #6

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    how reliable are the electronics on these flashes?
    I had a 285 that I bought new in 1982 for $99 and sold it 2 years ago for $80.
    I worked well all those years and was still working well when I sold it.
    I don't even know why I sold it and promptly bought 2 used 283 flashes which are working fine.

  7. #7
    brucemuir's Avatar
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    I have a bag full of 283's that I use for slaved kickers, accent lights, anywhere I need a little extra POP.
    I use them with quantum turbos sometimes.

    The older ones can have REAL high trigger voltage so be careful if you haven't tested it with a Volt/Ohm meter and you mount it to any camera with electronics.

    I always use a piece of electrical tape when mounted on a metal bracket or cold shoe just to be safe. I did get a "quiver" once when I had one on a speed graphic w/stroboframe.

    You can get them for 20usd bucks a pop all day long on ePrey and if you ask sometimes the seller will know the trigger voltage since it's widely know among "strobists" that the older ones pack a wallop.

    They are very robust and last a long time.

    Bruce
    http://www.brucemuir.com

  8. #8
    Ralph Javins's Avatar
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    Good morning, Hoffy;

    To promote longer life with your electronic flash units, use them. If you are not using them, pull them out of the bag once per month, put them on an AC house mains voltage power supply to conserve your batteries, and let the thing charge up for about 20 to 30 minutes. Then fire it and let it charge again for another 20 to 30 minutes. Repeat this about three times, then turn it off after the last firing and put it back in the bag. Repeat with the others in the bag.

    This will help to keep the main power capacitor for the flash tube properly "formed" so that it can safely and properly hold a full charge for the flash tube to use when it is fired. If you seem to be getting a weak light output when using the recommended camera settings for the flash unit, and the camera seems to work properly with another electronic flash unit, this could be the problem. You can try "reforming" the capacitor using a longer process like the maintenance process described above. If it does not come back, the only real cure is to replace the capacitor, or the entire flash unit. Yes, there is routine maintenance even for electronic flash units. We did not need to do things like this back when we had flash bulbs.
    Enjoy;

    Ralph Javins, Latte Land, Washington

    When they ask you; "How many Mega Pixels you got in your camera?"
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  9. #9
    fotch's Avatar
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    Quote Originally Posted by Ralph Javins View Post
    .......... We did not need to do things like this back when we had flash bulbs.
    Didn't some of the flashbulb units have a high voltage discharge circuit in them? I believe these would also have had capacitors.
    Items for sale or trade at www.Camera35.com

  10. #10
    Steve Smith's Avatar
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    Quote Originally Posted by fotch View Post
    Didn't some of the flashbulb units have a high voltage discharge circuit in them? I believe these would also have had capacitors.
    Not quite. Although most flash bulb circuits do have a capacitor, the circuit is formed by a battery (about 22 volts), a capacitor a resistor and the flash bulb all in series. Obviously no current flows when there is no bulb fitted as the circuit is broken. When a bulb is pushed into its holder it completes the circuit and the capacitor charges through the resistor and bulb until it reaches the same voltage as the battery. When the shutter is fired the camera's contacts connect the capacitor to the bulb allowing the full charge in the capacitor to discharge into the bulb.

    A simpler circuit would be just connecting the battery to the bulb via the sync. contacts but the battery's relatively high internal resistance would lead to erratic performance.

    A capacitor has a lower internal resistance and as such it can discharge faster and with more instantaneous current than the battery leading to more reliable firing.

    The resistor prevents sufficient current to flow to fire the bulb as you place it in the holder as that is definitely something you wouldn't want to happen!

    Steve.
    Attached Thumbnails Attached Thumbnails flash.jpg  
    Last edited by Steve Smith; 07-05-2010 at 01:36 PM. Click to view previous post history. Reason: Circuit drawing added.

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