Re: Stock Notice: Canon Speedlite 600EX II-RT at B&H Photo
midluk said:
Take extreme caution when opening a flash unit. The device operates with a very high voltage and the flash capacitor might still be charged to >500V. You definitely do not want to touch it or or cause a short circuit with a tool (at least not without first discharging it with a properly sized and power rated resistor). Without knowing where the capacitor is and what parts/wires are connected to it, you have a good chance to fry yourself or the rest of the electronics.
If you really do the modification, you should also make sure to remove (or decouple from the power supply) the HV generating circuit.
500 volts or more may sound high, but let's not forget that this is DC current. While it may scare the crap out of you or fry an I.C... it isn't going to stop a heart or cause burns.
Example: Let's say your 500 volts is correct (probably lower on a speedlight), and your skin resistance is 100,000 ohms. The the current would only be .005 amps and 2.5 watts of power. Plus again, this is direct current. The current only flows in one direction.
It is AC current that is so nasty. Sometimes even less than
.1 amp of AC can kill @ 110 volts. What does the killing is the rapid cycling of the current back and forth (alternating) along it's path through the body. It is also why you can't let go of the live wire. Not a problem with DC. In the United States household current is regulated to around 60hz. I think Europe is 50Hz. The old incandescent light bulbs we used to all use actually turned on and off 60 times each second. 60Hz was chosen because that is approximately the point at which the human eye doesn't see the on and off flicker.
It is current (in particular AC), not voltage that kills.
It is good to read about the battle between Tesla (DC) and Edison (AC). Thomas Edison was a very nasty person. Really nasty.
Anyway, I have forgotten more than I ever knew and it is very hard these days to retrieve that information from my cobwebbed mind.
In high school we used to leave charged capacitors laying around all the time and wait to see somebody pick it up. Great fun! Well, for high schoolers it was. We did the same in college.
Here is a nutty video of a guy discharging the capacitor on a 580EX and he talks about the possibility of it killing you. The real problem in the video is that he knows just enough about electricity/electronics to get himself killed one of these days.
https://www.youtube.com/watch?v=0mgpbD0IFvw
Here's a horrible video of four Chinese painters killed by alternating current. DO NOT WATCH IF YOU ARE SQUEAMISH IN ANY WAY. Very sad.
https://www.youtube.com/watch?v=6w13_6U9qL4