What causes the faint horizontal lines on my monitor?
Most likely, you have purchased a Cathode Ray Tube (CRT) monitor based on Sony’s Trinitron technology. These monitors use an aperture grill instead of a shadow mask , and the aperture grill causes the lines. You can see the line in the following photo: You can see a faint horizontal line just above the tip of the cursor To understand why the lines are there, we need to look at the shadow mask and aperture grill systems and understand the differences between them. • Shadow mask: The shadow mask in a CRT monitor is a metal screen filled with holes that sits just behind the phosphor layer. Red, green and blue electron guns each send a beam through a hole in the shadow mask to a single pixel triad of the tube’s phosphor layer. Although this method keeps the image sharp, it diminishes the potential brightness of the screen (See How Television Works for details). • Aperture grill: Instead of a metal screen, the aperture grill consists of tiny vertical wires. The pixels o
