It's always the maintenance issues that make everything so difficult.  It's the same thing with different kinds of ballasts that you find operating either a metal halide or high-pressure sodium light source.  There are several different parts and it's sometimes hard to determine exactly which you have wrong.  Many times in the case of HPS it's a matter of the lamp that has become old and needs to be replaced especially when it starts cycling.  If you see it going on and off from this type of system, you know the lamp needs to be changed, not the ballast.  But in case you find that the lamp won't come on at all, then you most likely have a ballast problem and you'll need one of our Universal high pressure sodium ballast kits to make a good replacement.  We recognize that sometimes you need all the parts to replace your worn out HID lighting to keep it operating properly.  HPS lamps have been a trusted source of light year after year, and it's the standard for applications like industrial, roadway or security lighting.  For your general information, the sodium lamp gives off a golden white color and metal halide illuminates with a white light, that is how you can tell the difference.  You can count on Universal Lighting Technologies for the widest variety of ballasts for all kind of lighting applications.  We're are one of the largest distributors of this product line and we can't think of a better way to maintain your home, municipal or security lighting.  The kits comes with everything you need including core and coil, capacitor, and mounting hardware which will make your job easier.