N340SG wrote:LIRR M-7s have a single U-shaped fluorescent bulb behind the number board. We've had to replace several of them already. The M-1s and M-3s have 3 incandescent bulbs behind each number board. At least when one or two bulbs blew or loosened, one could still see the number at night.
Why aren't they using white LEDs for this instead of fluorescents? I suspect several possibilities here. Maybe the driver circuits are faulty if the fluorescents are burning out too frequently, maybe they're just turned on and off too often, or maybe the vibrations are causing the filaments to break (yes, fluorescent tubes have filaments which aid in starting and are covered with material to help maintain an arc). BTW, nobody in their right mind would design something with incandescents nowadays even if they were used on the M1/M3. Besides the short life (which means a fortune on maintainance), they give a crappy yellow, uneven light when used in something like a number board. I hate them even for general room lighting as the ugly yellow light distorts colors and makes me squint. LEDs are really the way to go here. With a properly designed driving circuit, LEDs can last 100,000 hours compared to 20,000 for fluorescent and 750 for incandescent. They also don't suffer shortened life when turned on and off frequently as fluorescents do, nor are they affected by vibrations. Soon LEDs will even be bright enough for headlights (including train headlights). I'm currently working on an LED retrofit for fluorescents used in taxi ad signs. The fluorescent tubes were suffering premature failures because of the temperature and vibration extremes of a moving vehicle. Remember that LEDs have been increasingly used with great success in mass transit for the last decade or more. Maybe that's ultimately the way to go here.