TV picture problems can usually be spotted by checking to see if there are any issues or abnormalities with the TV's On-Screen Display, or OSD, which can be checked by using the TV's remote, not the cable or satellite remote, and clicking on the volume, channel and input buttons to see if the TV's projection lamp is working properly. If it isn't, those patterns that are usually displayed on the screen will look distorted or disappear entirely.
When a lamp stops working, it commonly makes a popping or cracking noise. Upon visual inspection, the thin glass tube may have shattered, or there may be a hole melted into the glass. A broken tube may also cause a discoloration in the outer glass envelope. It is very rare to find a broken tube that does not show any visible signs of damage. If this is the case, however, the lamp can be checked by replacing it with a new one and then checking to see if that makes a difference with the TV's OSD. A bad or failing lamp may also make a buzzing or arcing noise. This is likely caused by an excess voltage that is being bled off. These sounds will commonly occur when the TV is being restarted or turned on.
Different brands of TV sets show different visual signs of problems with their tubes, although almost any TV will have noticeable issues with its OSD. Hitachi TVs may have a dark screen or no picture. The LAMP light may also stay on constantly. For JVC TVs, there may be a dark screen, no picture or the front panel lights may blink simultaneously twice per second. Mitsubishi TV models show similar signs, along with a LAMP light that glows red. Sony and Toshiba TVs are similar.