joe_byrne

Doh! I had read the thread earlier, particularly Sarah's information. When I came back to it, I search for "pin 6" on the page. Not seeing it, I didn't bother looking further. (3, 4 posts above, it's referenced as "pin #6.") Gee, I feel dumb. Moreover, my curiosity was the same as James's: I was wondering if pin 6 carried Vce. I want to make a trigger/power mod, too, but I want to avoid opening up the flash (to reduce the risk of shocking myself!). Anyway, besides a pinpoint 3rd-degree burn and some burst blood vessels in my eyes, nothing too bad happened.

 

As to the strangeness of the lines, I find it strange that the trigger lines are also brought out. My guess is that the "automatic" modes use a photon transistor embedded into the vari-power module and directly control the shunting of power from the capacitor to the light tube. My guess is that the trigger lines start tell the transistor to begin switching current from pin 6 to pin 3. The amount of light received controls when the switch turns off.

 

My plan is to bring out +6v, convert to +3v (for the trigger), and rope in a potentiometer to control power. I wasn't going to remotely control power, but that could be done with a second trigger--each time this trigger is fired, it ratchets up the power, rolling over to the lowest power after reaching the top. You would need some kind of circuit (e.g. a microcontroller, but it's possible a simple counter would work) to handle this.

 

JB

The above doesn't describe Pin 6. I just found out the hard way that it carries the gazillion-volt output of the capacitor used to discharge the flash.

I have the same problem w/ my 28-105 3.5-4.5 Mark I. Peeling back the zoom grip, it doesn't look like the 28-135. It's not worth paying to have it lubed, but a smoother action would sure be nice.