Paul C. Buff, Inc. Technical Forum

It's the weirdest thing. The Cybersync works on all 4 of my units fine, until
I install the UMF Lightmod Mainframe WITH the barndoors. Take out the barndoors
and all the flashes go off properly. Put the barndoors back into the Mainframe and
only that light will fire, the others do not fire. What's happening here?

You are likely redirecting the light in such a way that the other lights cannot see it.

I just re-read your post, Do you have a reciever on all four lights, or just one?

The receiver is on one light. I thought it did not matter where the other lights are since the
Cybersync is radio controlled (no?), not infrared, and they can see around corners.

The Cyber Sync is radio, however the remaining lights are still line-of-sight optical slaves firing from the one light that has the reciever. To get all lights radio controlled, each would need its own reciever. The best solution for one light to trigger the others is to choose the light with the broadest spread (i.e. shoot through umbrella) or perhaps highest output to be the "master" and put the reciever on it. Success of the optical slaves will depend on many factors, including ambient light, proximity and color of walls or other bounce surfaces, orientation of the slave sensor, and others. Typically, though, indoor shooting will yield success with the slave eyes.

Ok now I get it. Thank you so much for your quick responses.