|
Really depnds on the quality of the tube. I do know that the average CRT goes downhill slowly. Poorer quality ones (IE: 1990's Zenith's) probably start noticeably going downhill after two years of regular use.
Another factor is in how many hours it has on it. Some CRT's will go on for hundreds of thousands of hours. Some might last only 20,000 hours. (Somebody told me that a year was about 8700 hours). If it's left on 24/7, it will go downhill faster then if it's only played 4 or 8 hours a day.
Luckily there's usually lots of adjustments to compensate for the aging of the tube. In older sets this is the case anyway. So far, certain Sony Trinitrons have had the most adjustments that I've seen.
I'd say that a tube is good until it starts to have color bleeding, or for a black and white tube, gets too dark to be useable.
|