Grumpy Finn

Sorry to pull up an old thread. Brand new YN560-tx and pair of 560 IV's. Still the same problem with Sony a6000 but I also noticed that the same problem persists when (off the camera) you ground the TX front (set) pin with ground, that's basically what your firing trigger does, I get one flash from both IV's, and then just the blue light. So it seems that there's something going on with the 560tx and the 560IV's.... just a note, I already replaced the 560tx with a new one, so at the moment I have two that do the same exact thing.... Has anybody come up with any kind of solution?