Paul C. Buff, Inc. Technical Forum

I recently bought a set of AlienBees CyberSynch transmitters and receivers. I purchased CyberSync CST Trigger Transmitter and two CyberSync CSRB+ Battery-Powered Trigger Receivers.

For some reason, when I mount my flash on the camera's hot shoe and plug the CyberSynch transmitter into the PC socket, it won't fire remote flashes. If I turn off the hot-shoe mounted flash, the remote flash fires. I tried this setup with a Canon 40D, 50D and a 7D and with Canon 580EX and 430EX flashes, all with the same result.

You should be able to connect via the PC terminal as well as have a hotshoe flash simultaneously. There may be a custom function setting that needs to be set to do so (I am not a Canon user, so I cannot say for sure). Depending on the age of the transmitter (more specifically, the voltage of the battery), there could be some voltage hang-ups. If this is the case, changing batteries should help (in the CST). To be sure, you are connecting via the PC port in the camera, correct? Not the PC terminal of the flash?

I am connecting the transmitter to the PC socket on the camera

My Canon D30 has the ability to use dedicated hotshoe flash and a connected PC flash at the same time.

RMS

It sounds like there is a problem with either the transmitter or the receiver

If the camera can trigger the CS system without the speedlite, the system is working fine. The only potential issue with CyberSync would be the battery in the CST (transmitter).

One other possibility, are the speedlites set to wireless slave mode?

The one in my hot shoe is set to "OFF". The one connected to radio slave is set to "SLAVE"

Try manual mode on the light connected to the receiver.

RMS

turn off the slave setting, as this activates the light sensitive eye. I cant say for sure on a Canon, but i have seen slave eyes and sync jacks cancel each other out on other speedlites. Alternatively, it just may change the way the flash responds in general. There is not need for the slave setting in order for it to be triggered via radio.