I have just bought a Yongnuo RF-602 Wireless Controller for myK200D on Ebay. When it arrived I eagerly connected the receiver to an old Starblitz 250BAZ I had laying around. This flash works fine on the hot shoe of the K200D. I mounted the transmitter on the camera hot shoe and fired the camera. The flash flashed. Tried again - nothing. Tried another old flash (Achiever 630AF) - nothing. The lights on both the TX and RX acted as they should as per the manual. Tried using the controller as a release and although the lights acted correctly and a half press activated the auto focus it would not trigger the . After a lot of tests I contacted the seller who sent me FOC another receiver unit. This time I tried it as a release first and it worked just fine. Tried it as a trigger with the Achiever - nothing. Plugged it back in as a release and this time it wouldn't work. All this points to a fault in the receivers caused by the flash units. Does anyone know if these older type flashes operate differently to the more modern ones? I think these flashes are triggered by a circuit being completed. Do more modern flashes operate like that or are they sent a seperate electrical charge to activate them? I opened up one of the RX units and nothing looked wrong with the wires or circuit board. Can anyone shed some on whether I might be able to save the Controller or should I just chuck it in the bin? It's not the batteries cause I bought new ones. Any suggestions appreciated.