Signs that a monitor is going bad include lines that appear on the screen, a blurry display or a failure to show anything at all. The exact symptom depends on what is going on with the specific monitor, according to New England Network Solutions.
If a monitor completely fails to turn on, the first thing to check is the connecting cables. After ensuring that the power supply and the input cables from the tower connect securely, the monitor is likely to come on. If it does not, it is potentially time for a replacement.
More common symptoms of a failing monitor include a blurry display and bright, white spots where colored pixels previously appeared. When a monitor shows a flickering or blurry screen, the magnetic field emitted by the speaker systems may be causing distortions in color or in the lines on the monitor screen. This is because the magnet inside the speaker has magnetized that part of the screen.
Many monitors have a "degaussing" option that allows demagnetization. Newer models do this automatically, but some older models still require manual degaussing, as stated by Microsoft. This option generally appears on a monitor's menu. Continued exposure to the source of magnetism keeps degaussing from working, which makes replacement necessary.
If the text on a screen using a Windows operating system is blurry, the culprit may be ClearType, a Windows gadget that is designed to make screen text easier to read, but can make it blurry in some cases. The Help menu in Windows provides the instructions for disabling or adjusting ClearType in that particular version of the operating system.