Interesting discovery about my 25 year old Sunpak Auto 433D Flash Units

Discussion in 'Accessories' started by roundball, Mar 19, 2014.

  1. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    Continuing to expand my preparations after reengaging photography, the other day I unpacked 3 Sunpak 433D units I had mostly used on light stands for some basic studio type shots. None of them would work...tried a couple different sets of fresh AA batteries but they wouldn't come up.

    Hoping they would come back to life given enough power / sustained current flow, I looked for but at the moment couldn't locate the 3 AC Adapter power units for them...so I unpacked the Sunpak 510V rechargeable External Powerpak I had left over from shooting my Son's wedding back in the 80's and charged it up for 24hrs...fortunately it took the charge and worked.

    Then I tried it on each of the Sunpak 433D's and it's power & strong current capability began bringing the 433D's back to life...as if the capacitors had to be massaged with high sustained current to get them going again.

    The more I kept firing the flash units with the powerful external battery the faster they began to recycle...and after a half hour with the big power unit I tried them again with their normal sets of 4 AA batteries and each of them now work fine again.

    Saved me from having to lay out a bunch more money for studio flashes...passing along the discovery in case it's of any interest.
     
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  2. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    Yes, it's good practice to cycle a flash through a number of flashes every now and then to keep the capacitor in shape.
     
  3. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    I didn't actually 'know' that...but figured there was no way 3 identical perfectly good quality flash units would all have developed the same sort of total defect while sitting in padded cases in an air conditioned house for a couple decades.
    Lucked out and got them all back...have since kept working with a smaller Sunpak Softlite 1600A I had left over and got it working again too.

    Next challenge is to figure out the best way to use these taller hot shoe flash units on the NEX-7 with the Hot Shoe adapter I recently picked up...the little Sony pop-up flash isn't tall enough to work well with long lenses...leaves a darker area in the photo where the lens barrel / hood blocks out some of the flash.
    And since I only use legacy Canon FD lenses, I can't use anything auto...I shoot everything in Aperture mode...may have to try Manual mode to pre-set shutter at 1/60
     
  4. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    It is not defect but known feature of electrolytic capacitors. Electrolytic capacitors have quite short self life if they are not being used (and they suffer from 'abuse' in flash type applications too) as the capacitor is formed from electrolyte and thin aluminium plate. The insulator between them is very thin layer of aluminium oxide that is formed by electrolysis when the capacitor is charged up. So there should no need to actually fire the flash but just charge them up regularly. There are several different qualities of electrolytic capacitors available and I think that the variety used in flashes suffers more from that problem than others as they have very high capacitance vs. size ratio (and low internal resistance).

    I use mostly manual mode with flashes. 1/160 s works fine. I think that manual mode is kind of aperture priority mode for flash photography as amount of light is constant.
     
  5. raay

    raay TalkEmount Regular

    58
    Sep 1, 2013
    be careful using this old flash onto your NEX-7 ,make sure the trigger voltage of the flash is less than 6 volts DC!! or else your camera will be fried , you can use wein safesync or build one your self following this Link
    http://personal.nbnet.nb.ca/rdlittle/htmlcontent/dpreview/vivitarmods/

    http://www.instructables.com/id/Taming-the-high-trigger-voltage-of-the-Vivitar-283/?ALLSTEPS
    I personally have used /using this circuit with a hanimex tz2 and now trigger voltage is around 4 volts ,ccompared to previous 150 volts!!
     
  6. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    Not sure what you mean by 'trigger voltage' ?
    Sounds like that would be a voltage level FROM the camera used to trigger the flash ??

    At any rate, not knowing any better I've already run tests on the NEX-7 with a Hot Shoe adapter, using both types of Sunpak flashes I had on hand...no "apparent" problem to the camera...but I won't use them any more until I better understand / resolve this question you've raised.

    In fact, I'll just set them aside for use as the studio type lights that I originally used them for, buy a suitable on-camera flash for the NEX-7, and not risk it / worry about it.
     
  7. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    Trigger voltage is in fact somewhat of a misnomer. The flash offers a certain voltage to the camera (the "trigger" voltage) and the camera shorts that voltage in order to trigger the flash. In earlier days the camera did that by simply closing a mechanical contact and these had no problem with the voltages in excess of 100 V supplied by the electronic flashes of those days; well, maybe on the long run, these high voltages will certainly wear out the camera's contact by arcing. Later flashes with more advanced electronic circuits aboard exposed the camera to much lower voltages, mostly below 15 V, usually 3...6 V. The cameras on their side got equipped with semiconductor switches that couldn't always handle high voltages, hence the warning made here.

    So it all depends on the voltage across the terminals of the flash and these can easily be measured by a modern digital multimeter. In this list your Sunpak 433D is said to have a trigger voltage anywhere 4 and 14 V, which is a low enough voltage apparently not to have damaged your NEX-7; could well be that there are circuit variations of this model during its lifetime, accounting for the different voltages mentioned. Sony is not very open on what the NEX cameras can handle; it's easy enough to get paranoid about this, but from my own experience I know a NEX-6 can handle at least 6 V otherwise mine would have been fried :).
     
  8. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    Well, I not only appreciate the warning that was brought up in my thread earlier, but your excellent operational explanation as well.
    The icing on the cake was the 433D voltage characteristics you went to the trouble to supply, and that puts my mind at ease.

    I had no idea of the potential risk due to changes in technology, and there was nothing intuitive that struck me to even think about it...just never occurred to me.
    With my particular outdoor photography interests, its rare that I use an on-camera flash but thought I should have one on hand 'just because'...at least now I don't feel like I have to buy a new one after all.

    Thanks again...
     
  9. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    FOLLOW-UP NOTE:

    I just checked the voltage across the pins of one of my charged up / ready to fire Sunpak 433D's...measures 3.8 volts.
    Looks like I dodged a bullet and am good to go.
     
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  10. michelb

    michelb TalkEmount Regular

    198
    Oct 27, 2013
    Greater Montreal area in Quebec, Canada
    Michel Brien
    For vintage older flashes voltage see here http://www.botzilla.com/photo/strobeVolts.html

    As for keeping your flash capacitors in good health, i remember older Minolta flash instructions recommending to use the flash every 6 months in the following manner

    - Do not let batteries in if not used for more than 2 weeks.
    - Let it recycle 1 minute after the ready light is on, then trigger a test flash
    - Repeat this 3 times and let the flash recharge the capacitor for an extra minute, then shut down, remove batteries and store.

    I have done this with 8 Minolta 320/320X/360PX flashes that i own since about 1990 but who were actually made in the mid '70's and they all work. Sometimes they need a few flashes after were sleeping for a long time but after that they are all consistent and reliable.
     
  11. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    Yes, I bookmarked that link from "addieleman"s post above...good info.

    In fact, in addition to my Sunpak 433D's being listed, it also lists my very small Sunpak Softlite 1600A.
    The little thing only uses 2 AA batteries...but the list said somebody measured the pins at 46 volts.
    I checked mine and got almost the same thing, at 44.5 volts

    I actually already tried it on the NEX-7 (not knowing any better)...it worked fine and the camera still seems fine...but until further official specific knowledge about what the NEX-7 can handle, I won't use it on the camera again...just in a studio situation on a light stand or something.
     
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  12. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    PS:

    Just got my Email reply back from Sony Support confirming that flash trigger voltage should not exceed 6 volts on the NEX-7.
     
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  13. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    Well, the community must be thankful that you tested the NEX-7 with a 44 V trigger voltage even if you were not intending to run that kind of risk! :thumbup: Apparently Sony is playing it safe.
     
  14. roundball

    roundball TalkEmount Hall of Famer

    Oct 8, 2013
    USA
    Kind of like the old saying: Ignorance is bliss :rolleyes:
     
  15. Hawkman

    Hawkman TalkEmount Top Veteran

    943
    Sep 10, 2013
    Virginia, USA
    Steve
    Searching back through the forum for "trigger voltage", I found this and it seems to answer my question re: my own old Vivitar 550FD (for Nikon) Auto Thyristor flash unit. Tested out at 8.9-10.6 V DC, it obviously exceeds the Sony limit of 6 V DC, assuming that the newer Multi Interface Shoe on the A3000 and other newer cameras is similar in voltage tolerance to the shoe on the NEX-7.

    Thanks, back through time, for the good info. Ah, the value of a searchable forum filled with knowledgeable / curious folks. :)
     
  16. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    Flashes operate at roughly 300 V. There is a switching mode power unit combined to a transformer that brings voltage to these levels. The triggering voltage may be anything between this 300 volts and a few volts. Old ones have simple thyristor circuit that exposes all that voltage, modern ones have IGBT (Insulated Gate Bipolar Transistor) that is switched on or off with a microcontroller.
     
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