Vivitar 200 fails to fire...

Discussion in 'Casual Photo Conversations' started by hjoseph7, Jun 11, 2021.

  1. I decided to open up one of my 2 failed Vivitar 200 which I purchased from eBay for less than $20. I have 2 working ones, but I wanted to see if i could find out why the other 2 did not fire. The little orange light(ready-light) seems to be working, but when i hit the shutter button, the flash does not fire ?

    Take a look at that HUGE capacitor, never saw one that big !?. It is a 330V 250uf capacitor, so I really don't want to mess with it until I'm 100% sure it is fully discharged. Do they still sell capacitors like this one ? I'm guessing that is where the problem lies since everything else looks OK ? The Blue wire on the left comes from the battery chamber.

    Vivitar 200.JPG
     
    Last edited: Jun 11, 2021
  2. Perhaps you can ask a friendly electrician or refrigeration tech UEImeter.jpg if they have a meter with a capacitor tester. Many meters used by refrigeration people have the capability to test capacitors.
     
  3. Nothing compared to a modern flash capacitor of 1400uF and 350 vw. They hold 75 Joules of energy, compared to the pitiful 13.6 Joules of that little Vivitar thing. However, there's more than enough energy in that little capacitor, when fully charged, to kill or badly burn someone several times over.

    Don't mess with it unless you know what you're doing!

    The capacitor can be discharged using a high wattage and well-insulated resistor of about 1000 ohms value. And best to use thick rubber gloves while applying the resistor.

    Or you could just carefully put the case back on and throw that junky old flash away. Since the fault could be anything from a faulty switch, a loose wire or an open-circuit trigger transformer. Worth spending maybe hours trying to find the fault, risk at minimum a nasty 'tickle' or burn and only eventually find that a vital component is obsolete and unobtainable? I don't think so.
    Cappies.jpg
    Now this (left) is a huge capacitor. The one on the right is the main storage capacitor out of a mid-power hotshoe flash.
     
    Last edited: Jun 12, 2021
  4. I once tried to repair an Olympus T32 and foolishly discharged the capacitor with a piece of wire. After the flash and bang I could hardly see or hear for some minutes. And a little Minolta point and shoot gave me my worst ever shock - and me, a veteran of 40 years as an electricity mains engineer.
     
    za33photo and ajkocu like this.
  5. If the capacitor is shorted or leaked the ready light is no going to come on. If the capacitor is open the ready light woulrkd come on faster than normal. Capacitor that size is quite common. In my daily work I deal with 2200 mfd rated atl 600V. 5 of them connected in parallel to form a 11,000 mfd capcitor and they were charged up to 600V. They supply the DC power to the servo amplifier.
     
    rodeo_joe|1 likes this.
  6. As Igor says, approximately:
     
  7. I see some corrosion on some wires right under what looks like an Inductor ( the spool with the copper wire wound around it) . I'm going to try cleaning those wires with some vinegar while avoiding the capacitor altogether to see what happens...
     
  8. Its amazing how well these things are made. and easy to follow.
     
    za33photo likes this.
  9. It's amazing how well these things are made. All the components look top-notch and the soldering is really good. I couldn't find a service manual for this flash, but I did find the service manual for the 283. Maybe it might give me some hints ?
     
  10. If it makes the whiny noise and the ready light comes on, the supply is likely OK. Most likely the trigger transformer is bad, or the tube itself. Check corrosion and the back of the PCB for cracks and bad joints. IMO, not worth messing with. Photo-flash capacitors are of unique construction for the application and not often readily available, but they also seem to hold up well.
     
  11. You jest, surely?
    I've seen better amateur lash-ups on Veroboard than the trigger circuit shown top centre of your picture Harry.

    If you're going to slop vinegar all over the circuit - not recommended - then please discharge the capacitor first.

    Here's my purpose made capacitor discharging resistor. The 'EZ hooks' allow attachment while keeping fingers well away from the capacitor terminals.
    IMG_20210612_183253.jpg

    I've used a 3000 ohm (3Kohm) resistor, simply because it was lying around unused, but anything between 1 and 10 Kohm would do. It does need to handle a fair wattage though, otherwise it'll get hot and maybe smoke or burn out during discharge.

    For completion; the formula for capacitor discharge is:
    v/V = e^-t/(C.R) where v = voltage after discharge time t, V = initial voltage, C = capacitance in Farads, R = resistance in Ohms, t = discharge time in seconds and e is the natural number 2.7182818....

    Therefore a 1000 Ohm resistor would discharge your 250 uF capacitor to less than 1/50th of its initial voltage in one second - theoretically.

    My 3000 Ohm resistor would take 3 seconds to do the same, but I'm usually dealing with higher value capacitors and leave it attached for at least 30 seconds before touching any circuitry.
     
  12. Thanks, I have a whole set of resistors lying around somewhere in my "Joe knows resistor kit" I'll see if i can find one about 5Kohm. If I can remember where I put that kit ? How do you know when the capacitor is fully discharged ?
     
  13. Roger G

    Roger G Roger G

    Because it no longer works as a defibrillator?
     
    rodeo_joe|1 likes this.
  14. I use a Fluke meter in voltage measurement in Low Z mode which has a 3000 ohms input impedance. Works the same as your resistor but it also indicates how much voltage is left.
     
  15. OK
     
  16. But this feature is strangely only available in some of the Fluke cheapest models and most expensive models and not in the mid range ones.
     
  17. Fluke sell a 'cheap' meter?!
    In theory it never gets fully discharged. An exponential decay never reaches zero.

    In practice the voltage will go down to maybe a fraction of a volt after several seconds with a few Kohms load.... but it will 'bounce' back to a few volts as soon as the load is removed. Anything reading under 20 volts or so is going to be safe to touch, but you might still get a meaty spark if the capacitor terminals are shorted.
     
  18. I have the Fluke 113 and 114 both have this lo Z feature. They are less than $150. I don't see in mid range ones like the 179, 87V etc.. Not even the 287. It's on the 289 which is almost $600.
     
  19. I was looking at the Fluke 117, but unfortunately right now my Brymen BM235, or my DR Meter MS88 will have to do... Does the polarity of the Capacitor play into all of this ?
     
    Last edited: Jun 13, 2021
  20. The capacitor used in flashes do have polarity and it must be charged with correct polarity. But for discharging it the polarity doesn't matter. Just use your meter to check the voltage across the capacitor. If it's low enough it's OK to work on. I think one of your DMM does have capacitor measurement function you can use that to check.
     
    hjoseph7 likes this.

Share This Page