A CRT monitor is a device based on a cathode ray tube. This technology was developed back in 1897 by the German scientist F. Brown. Initially, it was created as a specialized tool for measuring alternating electric current (oscilloscope).
CRT monitor and its design
The main element of such a device is a kinescope. It consists of a glass hermetic tube from which air is removed (that is, vacuum inside it). One end of the tube is flat and wide - this is the screen, and the other - long and narrow - this is the neck. The front side of the tube inside is covered with a phosphor composition (based on yttrium and erbium). The next element of the CRT monitor is an electron gun, from which, under the influence of an electrostatic field , an electron stream emerges, due to which an image appears on the screen. Elementary particles pass through a metal grid and fall on the inner side of the glass screen, covered with phosphor dots of different colors. A special deflecting system provides a consistent hit of the beam on the screen. Deviation systems are of two types: saddle-shaped and toroidal. The system consists of inductors located at the neck of the tube.
The next element defining a CRT monitor is the vertical and horizontal scanning unit. This unit is the main source of interference in the operating frequency range. The power consumed by these nodes is one of the serious factors that must be considered when designing a CRT monitor. The next structural element is the intensity modulator, which, together with the accelerating system, operates on the principle of potential difference. Thanks to these nodes, electrons acquire energy, part of which is spent on the luminosity of the phosphor.
RGB technology
Typically, a CRT color monitor contains 3 electron guns, and a monochrome one. These guns correspond to the main colors: green, red and blue. Their combinations are capable of creating an infinite number of shades and colors. To control cathode ray tubes, control electronics are required that determine the quality of the monitor. It is the difference in the quality of electronics created by various manufacturers that is the criterion that determines the difference between CRT monitors, despite the fact that the cathode ray tube in them is the same. So, each of the guns emits a stream, which affects the phosphor points of a different color. An electron beam of the same color should only affect the elements of its color. To achieve just such an action of the beam, use a special mask, the structure of which depends on the type of picture tube.
Repair of CRT monitors
The main malfunctions of CRT devices are a malfunction of the power supply. Most often this happens due to power surges. If the power supply fails, then most often the accompanying breakdowns of other modules occur, for example, a violation of the color rendering, image distortion. In addition to power surges, the causes of failure of monitors are often mechanical damage (shock), exposure to electromagnetic radiation sources, dustiness of the monitor, overheating, aging of elements. Violation of the temperature regime can lead to failure of the video processing board and the formation system. Horizontal scan disruption occurs due to breakdown in high voltage circuits and TDKS. One of the reasons for this phenomenon is dustiness.