The top strobe light on the WCGQ-FM transmission tower had stopped working. We thought perhaps the strobe tube or flashhead had failed or suffered a lightning strike, which would have required bringing in a tower and rigging crew to climb the tower to perform the repairs. But in this case we sort of got lucky, with the problem turning out to be a blown resistor and circuit board damage in the Flash Technology PC310-4 controller/power supply unit.
The three Flash Technology PC310-4 controller/power supply units which drive the three strobe lights on the WCGQ-FM transmission tower.Measuring the output voltage being sent to the top strobe from the controller/power supply unit. The unit was not sending the normal ~1,000 volts of “pulsed” voltage to the strobe, which is why the strobe was not firing as it should.The first of two problems I found to be the cause of the strobe malfunction: the burst resistor had… well, literally “burst.” It had either taken a lightning hit, or simply burned out due to excessive voltage or current flow.The second problem I found was some burned-out components on the timing/trigger circuit board. I had brought a complete, working controller/power supply with me in case it was needed. I replaced the damaged circuit board by using the one from the spare/emergency unit I had taken with me to the site. I also keep a kit of various spare repair parts for these controllers, so I had a replacement burst resistor at hand. Changing out the circuit board is a fairly easy and straightforward process, as it’s easily accessible; however, changing out the burned-out burst resistor is a bit of a challenge if you don’t want to do some major disassembly in order to get to the screws which attach the wiring to the resistor terminals and ceramic insulators/stand-offs. While the circuit board was removed for replacement, it was much easier to take the route of removing the two screws which hold the ceramic standoff/insulator posts to the frame, allowing me to pull the burst resistor down below the controller chassis just enough to disconnect and change out the resistor. That was much easier and faster than the almost total disassembly of the controller which would normally be required just to get to the burst resistor.With the burst resistor and timing/trigger board replaced, the top strobe was back in service. Day/night switching was working properly, and all three strobes were flashing at the correct rate, with correct light intensity in both day and night modes. For once, we did not have to bring in a tower crew. We like those guys, but we prefer NOT being in the position of having to call them up!
