Paul C. Buff, Inc. Technical Forum

I have a pair of AB800s and a Cybercommander connected with 2 CSR+.

I can get them to trigger the lights with the mini-plug sync connections, but when I connect the telephone/data cables instead, the flashes will not trigger and start firing rapidly/uncontrolably.
I do have a dummy plug in the sync jack.

Does anyone have an idea what is going on?

Sounds like a power supply issue. You could have noise on the AC line. Switching to a different circuit may isolate that as a problem. Also, a bad power strip, extension cord, or power cord can cause this as well. Since both lights are doing this, I would not suspect the power cords. I would suggest removing anything between the cords and the wall outlet to see if the problem persists. If not, you can then add back one component at a time to see when this behavior starts again. The last component added is the/a culprit.

Could this be caused by using "straight" phone cords instead of "crossover" cords?

Quite possibly, yes.