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  1. #11
    fotch's Avatar
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    Since it does not supply voltage, rather, just closes the circuit like a switch, test it with the meter set for continuity.
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  2. #12
    Rudeofus's Avatar
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    There are several things chained together in your setup and I would recommend you test each part of the link to find out where the problem sits:
    • Check out the voltage between trigger input and hot shoe ground for each flash that you ever tried with your radio triggers. If the voltage of any of your flashes is beyond 10V, you have likely fried your trigger receiver(s). Get new receivers and never connect that flash to radio triggers ever again.
    • Set your meter to current measurement (10A range if possible) and connect the test strips to trigger pin and hot shoe ground. If the flash doesn't fire, you can't trigger it this way, don't use it with radio triggers. I have heard of flashes that only trigger with the clock/data protocol used by the specific camera brand.
    • I assume that the trigger output of the radio trigger won't stay on very long, so a resistance measurement may or may not show that the output went active. If you use acoustical continuity measurement, you should get an audible beep when the output goes active. This works with my RF-602.
    • Now you know that your flash won't fry the receiver, that it responds to a short circuit between trigger input and hot shoe ground, and that the radio link works. Now connect flash and receiver and try the test button. The flash should fire now. If it doesn't: compare flash hot shoe and receiver hot shoe for possible mismatch.
    • Leave flash and receiver connected, and use your meter to create a short circuit between trigger input on the radio transmitter and its hot shoe ground. If the flash doesn't fire, something in your transmitter is broken.
    • Set your multimeter to acoustic continuity measurement again and check whether the camera actually actuates its hot shoe trigger output.
    • If the flash fires when manually shorting the transmitter's trigger input but not when the camera fires, there might be a mismatch between camera hot shoe and radio transmitter hot shoe. I know for instance that I can slide my transmitter onto my RZ67 hot shoe both ways, but only one way will trigger the flash.

    Good luck!
    Trying to be the best of whatever I am, even if what I am is no good.

  3. #13
    Steve Smith's Avatar
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    Quote Originally Posted by Rudeofus View Post
    Check out the voltage between trigger input and hot shoe ground for each flash that you ever tried with your radio triggers. If the voltage of any of your flashes is beyond 10V, you have likely fried your trigger receiver(s).
    The opto thyristors in my cheap Cactus triggers are rated at 400 volts. You could not possibly find any for sale which would be destroyed by voltages in the tens of volts. I couldn't even find a similar device rated as low as 250 volts which is what most modern cameras are rated at. This makes me think that modern cameras use a 400 volt device and the manufacturers state 250 volts for a large margin.


    Steve.

  4. #14
    Rudeofus's Avatar
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    Quote Originally Posted by Steve Smith View Post
    The opto thyristors in my cheap Cactus triggers are rated at 400 volts.
    There is a German language FAQ for these Yongnuo RF602 radio triggers which claims 50V and 100mA as the absolute limit.

    If this FAQ is correct, an old flash with typically 300V would likely destroy the receiver.
    Trying to be the best of whatever I am, even if what I am is no good.

  5. #15
    Steve Smith's Avatar
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    It would be interesting to find out what the component is in these and look up the data sheet for it.

    A normal flash trigger circuit consists of a a high value resistor (about 1M) connected from the HV supply to a low value capacitor (about 10nF). All the trigger has to do is discharge the small capacitor into the trigger transformer. The amount of energy involved is very small.


    Steve.

  6. #16
    Rudeofus's Avatar
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    Quote Originally Posted by Steve Smith View Post
    It would be interesting to find out what the component is in these and look up the data sheet for it.

    A normal flash trigger circuit consists of a a high value resistor (about 1M) connected from the HV supply to a low value capacitor (about 10nF). All the trigger has to do is discharge the small capacitor into the trigger transformer. The amount of energy involved is very small.
    I would say this was the case in the stone age. Around bronze age flashes became more intelligent and started talking to cameras in more advanced terms than "fire flash" and "quench flash", and that was the time when 5V (or 3.3V) signals became the norm. If you hook one of these stone age flashes with their 300V trigger voltage to my EOS 3 (early medieval age) it will burst in flames. So will my RZ67 (late Renaissance) and the Yongnuo RF602.

    Note that the ability to handle 300V does not start and end with the actual switch, you need to make 100% sure that all insulation from that switch all the way to the hot shoe is rated for this voltage. Crammed as modern SLR cameras are, it comes as little surprise that only few modern camera models can handle high trigger voltage.
    Trying to be the best of whatever I am, even if what I am is no good.

  7. #17
    Steve Smith's Avatar
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    Most current cameras are rated at 250 volts according to their manuals*. And despite extra control circuitry, the 'stone age' method of discharging a small capacitor into a trigger transformer to create an ionising pulse is still the way they work today, albeit with a couple of thyristors to turn it off when enough light has been received.

    (* the Nikon D100 I foolishly bought in 2003 was rated at 250v).


    Steve.

  8. #18
    Rudeofus's Avatar
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    Quote Originally Posted by Steve Smith View Post
    Most current cameras are rated at 250 volts according to their manuals*. And despite extra control circuitry, the 'stone age' method of discharging a small capacitor into a trigger transformer to create an ionising pulse is still the way they work today, albeit with a couple of thyristors to turn it off when enough light has been received.
    This doesn't seem to be the case in Canon land. While some camera models can handle 250V if connected through their PC sockets, their hot shoes are limited to 6V. Likewise my RZ67 accepts 12V max. This posting claims that only Nikon cameras can take 250V through their hot shoes.

    Please be careful before you claim that any camera can handle high trigger voltages, 300V can do a lot of damage to electronic circuits even if only a small capacitor is discharged.

    And just before this pops up: sensitivity to high trigger voltages is not an issue of analog vs. digital camera. While most ancient cameras can handle 300V without problems, I would at least double check any camera less than 20 or 30 years old, see my examples of EOS 3 and RZ67.
    Trying to be the best of whatever I am, even if what I am is no good.

  9. #19
    Steve Smith's Avatar
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    The hot shoe vs. PC socket thing is in my opinion, nonsense. The two will have the same or similar circuits. most likely connected in parallel. I think the warning about hotshoes is the worry that a charged flash could be pushed into the hotshoe and the centre contact could momentarily connect to a pin it's not supposed to connect to. I can't see that the actual trigger circuit will be any different to that connected to the PC socket.

    I find it strange that an RZ67 is rated that low. I know the shutter is electronically timed but I would have thought that the shutter is still triggered by mechanical contacts.

    I'm sure that when the RZ first came out, people just used them with their existing flashes without any worries. This sync. voltage thing is a more modern thing.


    Steve.

  10. #20
    Rudeofus's Avatar
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    Quote Originally Posted by Steve Smith View Post
    The hot shoe vs. PC socket thing is in my opinion, nonsense. The two will have the same or similar circuits. most likely connected in parallel. I think the warning about hotshoes is the worry that a charged flash could be pushed into the hotshoe and the centre contact could momentarily connect to a pin it's not supposed to connect to. I can't see that the actual trigger circuit will be any different to that connected to the PC socket.
    Here is a quote from Chuck Westfall about Canon cameras and high trigger voltage strobes. He basically tells his Canon folks that hooking up such a flash to a Canon camera might even work but can mess up things in the long run. Don't do it, and if you have to, there are safe sync adapters which convert the high trigger voltage to one the camera is rated for.

    I do agree that a camera like the RZ67, which was marketed as a professional studio camera, should support higher trigger voltages out of the box, but for whatever reason Mamiya thought this would not be necessary. BTW don't forget that this camera used to cost more than US$4000 and wasn't sold at Fry's Electronics, so one would assume that people buying it would either know or learn from Mamiya's sales people which flashes they could safely use with their camera.

    And all this is completely besides the main point anyway: don't connect a flash with more than 50V trigger voltage to Yongnuo radio triggers, they are not built for that.
    Trying to be the best of whatever I am, even if what I am is no good.

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