Number of views：1842order Release Date：2020-11-26

The monitor is the basic output device in a computer and serves as a window for people to communicate with the computer. It is a durable component in computer configuration, and many computer upgrades are carried out on the premise of retaining the monitor. Computer hosts can generally only be used for two to three or four to five years before being phased out due to the increased technical requirements of the new software being used; But for ordinary users, the monitor can be used for about ten years, but during use, they often encounter problems with the monitor. below Golden Eye DisplayA brief introduction to some basic knowledge of display components, hoping to be helpful to everyone.

1. Capacitor:

The common labeling method for capacitors is direct labeling, with two commonly used units: pF and μ F, which are easy to recognize. But some small capacity capacitors use numerical notation, usually consisting of three digits. The first and second digits are significant numbers, and the third digit is a multiple, indicating how many zeros should follow. For example, 343 represents 34000pF. Additionally, if the third digit is 9, it represents 10-1 instead of 10 to the power of 9. For example, 479 represents 4.7pF.

When replacing capacitors, attention should be paid to the voltage withstand value of the capacitor, which is generally not lower than the voltage withstand requirement of the original capacitor. In circuits with strict requirements, the capacity should generally not exceed ± 20% of the original capacity. In circuits with less strict requirements, such as bypass circuits, it is generally required to be no less than 1/2 of the original capacitance and no more than 2-6 times the original capacitance.

2. Resistance:

There are three main types of resistors: carbon film resistors, carbon film resistors, and metal film resistors. The most widely used is carbon film resistors, and the highest end is metal film resistors. The resistance value of a resistor is indicated by a color ring, with the most common being a four-color ring and a five color ring. If a four-color ring is used for labeling, the first color ring is a ten digit number, the second color ring is a single digit number, the third color ring is the multiplication number, and the fourth color ring is the error rate. For example, if the color arrangement of the resistor in the four-color ring is red, blue, brown, and gold, then the resistance value of this resistor is 260 ohms with an error rate of 5%.

3. Transistor:

The transistors used in color displays mainly include crystal diodes, crystal transistors, thyristors, and field-effect transistors, among which the most commonly used are transistors and diodes. How to correctly judge the quality of transistors is one of the key factors in learning to repair displays.

1 Crystal diode:

Firstly, we need to know whether the diode is a silicon tube or a germanium tube. The forward voltage drop of a germanium tube is generally between 0.1 volts and 0.3 volts, while that of a silicon tube is generally between 0.6 volts and 0.7 volts. The measurement method is to use two multimeters to measure. When one multimeter measures its forward resistance, use the other multimeter to measure its tube voltage drop. Finally, the value of the tube pressure drop can be used to determine whether it is a germanium tube or a silicon tube. Silicon tubes can be measured using the R × 1K range of a multimeter, while germanium tubes can be measured using the R × 100 range. Generally speaking, the greater the difference between the forward and reverse resistance of the measured diode, the better. Generally, if the forward resistance is several hundred to several thousand ohms and the reverse resistance is several tens of thousands of ohms or more, it can be preliminarily concluded that this diode is good. At the same time, the positive and negative terminals of the diode can be determined. When the measured resistance value is several hundred ohms or several thousand ohms, it is the forward resistance of the diode. At this time, the negative probe is connected to the negative terminal, and the positive probe is connected to the positive terminal. Additionally, if the forward and reverse resistance is infinite, it indicates an internal disconnection; A diode with the same resistance in both forward and reverse directions is also problematic; A zero resistance in both directions indicates a short circuit.

2-crystal transistor:

The transistor is one of the most common components in color displays, and how to judge the quality of the transistor is the key to color display maintenance. To determine the quality of a transistor, the method is to use the R × 1K or R × 100 range of a multimeter for measurement. For NPN transistors, when the negative probe is connected to the base and the positive probe is connected to the collector and emitter respectively, the forward resistance of the two PN junctions measured should be several hundred ohms or several thousand ohms. Then, the probes should be swapped and the reverse resistance of the two PN junctions should be measured, usually several tens or hundreds of ohms or more. Then use a multimeter to measure the resistance between the emitter and collector, and after measuring, swap the probe once. The resistance value of both measurements should be above tens of kiloohms. This type of transistor can be determined to be basically good.

How to determine the amplification capability of a transistor, which mainly functions as an amplifier? The method is to set the multimeter to R × 100 or R × 1K. When measuring an NPN transistor, connect the positive probe to the emitter and the negative probe to the collector. The measured resistance should generally be several thousand ohms or more; Then connect a 100 kiloohm resistor in series between the base and collector, and the resistance value measured by the multimeter should significantly decrease. The greater the change, the stronger the amplification ability of the transistor. If the change is small or there is no change at all, it indicates that the transistor has no amplification ability or weak amplification ability.

4. Integrated circuit block:

To judge the quality of an integrated circuit block, a multimeter can be used to measure the working voltage, resistance to ground, and working current of each pin of the integrated block to ensure that they are normal. You can also remove the integrated block and measure the resistance between each pin of the integrated block and the grounding pin to see if it is normal. When removing the integrated block, you can measure the ground resistance of each pin of the external circuit to see if it is normal. It should be noted that when replacing integrated circuit blocks, attention must be paid to soldering quality and soldering time. When replacing integrated circuit blocks, it is generally required to use integrated circuits of the same model and specifications for replacement. When the original model and specifications of the integrated circuit block cannot be found, it may be considered to replace it with an integrated circuit block with similar functions. However, it should be noted that when replacing, it is necessary to clarify issues such as power supply voltage, impedance matching, pin position, and peripheral control circuit.

5. Row output transformer:

Row output transformer (commonly known as high voltage pack) is one of the major components that frequently encounter problems in displays. The main problem it is prone to is internal short circuits. At this point, the power supply voltage can be checked using a multimeter to determine if it is normal. If the insulation performance of the output transformer decreases or there is a local short circuit between turns, it will cause a surge in the scanning current and a decrease in the output voltage of the switching power supply. Therefore, the short circuit of the output transformer can be determined by measuring the power supply voltage.