I am helping a friend who owns a restaurant fix the marquee sign in his front parking lot. The sign was working fine for the last 3 years. The sign uses two separate banks of 5 linear 72" (F72T12/D/HO) tubes per ballast. The pin style is recessed the bi-pin. I think the voltage is220VAC. Unfortunately, the label on the ballast has aged away and is now unreadable, but I am quite sure it is one of those pricey six tube ballasts rated at up to 36 feet. There are a total of two ballasts, one for each bank of five tubes, for a total of ten tubes. One bank of five tubes works just fine. However, on the other set of five, only the tube, the one physically closest to the ballast lights up. All of the bulbs have been confirmed to work by removing them and testing them in the working lower socket. I think this is just an open wiring problem. I now need to troubleshoot this bank of tubes while standing on top of a 12ft step ladder in the middle of a parking lot.
- Since one lamp still works, can the ballast be considered 100% good?
- Should I just use a meter to confirm 220VAC at each of the sockets?
- Can I use an inductive voltage tester to sense the voltage to the sockets?
- Should the bulbs be in or out of place when testing the sockets?