How to judge the fault of LCD screen blurring?

Overview of the phenomenon of blurred screen failure: There is an image on the screen, but the image is covered with interference such as dots, flakes, and mosaics. Corresponding maintenance direction: Check the signal source, logic board, LVDS signal, main board, screen parameters, and LCD screen. Fault phenomenon of blurred screen: the user menu is normal, but the image is blurred. Corresponding maintenance ideas: Check the motherboard and scaler processing chip circuits, and repair the chips. Fault phenomenon of blurred screen: irregular blurred screen, the middle image of the LCD display screen is mixed with many small colored dots. Corresponding maintenance idea: The LVDS plug-in cable is not in good contact. Flowering screen failure phenomenon: After repeated power-on, the stripes and colors of the flowers change. Corresponding maintenance idea: check the logic board flower screen failure phenomenon: after repeated power-on, the stripes and colors of the flower remain unchanged. Corresponding maintenance ideas: the screen itself has a high chance of failure. Flowering screen failure phenomenon: the image is disturbed, and the characters are also disturbed. Corresponding maintenance ideas: logic board, screen signal connection, digital board signal output circuit. Flowering screen failure phenomenon: the characters are normal, but the image has block and dot interference. YPbPr input signal, no interference. Then input from the AV port, the image appears interference. Corresponding maintenance ideas: frame memory false welding, image enhancement processing IC control signal line broken. Fault phenomenon of blurred screen: the images are all dotted, finely broken, and the characters are normal. Corresponding maintenance ideas: the fault is in the video decoder circuit. Because the faults generated by the image enhancement processing circuit are massive, not finely divided. Flowering screen failure phenomenon: there is distortion or netting interference on the image. AV test machine everything is normal. Corresponding maintenance ideas: middle-amplification and high-amplification circuits. Fade phenomenon: The image is regular and blocky. Corresponding maintenance idea: The communication between the motherboard cache and the main chip is poor. Fault phenomenon of blurred screen: ghost image of blurred screen, messy color stripes on the whole screen Corresponding maintenance idea: turn off the image contrast to judge. If the contrast is turned off, the lack of color in the image indicates that the fault point is in the format conversion circuit of the motherboard and the LVDS connection line. On the contrary , If the contrast is turned off, the image is basically normal, which means that the format converter of the T-CON board is not working properly. The logic board is mainly used for the power supply of the screen and the chip, the format converter communicates with the frame memory, and the data of the screen memory is damaged. Typical failures of a bad logic board Typical failures of a bad logic board: No image, intermittent colored lines vertically across the screen, and no characters (this is important). The upper screen voltage is generally 5V or 12V, depending on the model of the screen. Then test the voltage on the LVDS output interface to see whether the static and dynamic conditions change. If there is no change, it can basically be judged that there is a fault on the logic board. (With the pointer multimeter, you can see that the needle has a slight jitter, generally around 1.2V) . As long as the format is the same as the upper screen voltage, it can be replaced. The LVDS lines from the motherboard to the logic board have certain rules. The red line on the side is the positive pole of the power supply, and the black line is generally the negative pole of the power supply. bit; 8 pairs/double 6 bits; 10 pairs/double 8 bits). Now some logic boards and screens are connected together, which is called X+C integrated type. Generally, the screen is less than 32 inches, and the screen above 32 inches is generally composed of X+C separate type. Damage to the logic board will cause the screen to not display images normally, and of course there is no menu display, but the buttons and remote control are functional. Characters are inserted from the last stage of the CPU circuit. The difference between the artifacts of the logic board and the artifacts produced by the screen: the artifacts of the logic board appear as regular artifacts up and down, we can change the signal source or change the 4:3 mode to confirm. Logic board maintenance ideas: 1) Check whether the main chip power supply IC, filter capacitor and other vulnerable components are obviously burnt black or abnormal in color; 2) Check whether there is a short circuit at each power supply test point, the resistance value becomes smaller, and whether the insurance is open; 3) Test whether the power of each power supply test point is normal, that is, the power supply Vcc---5V/12V, the main chip---3.3V, 2.5V, 1.8V, 1.2V, etc., VAA---14V, VGH---about 26V , VGL --- about negative 6V, ④ VREF --- 13V, VCOM --- 6V); 4) Check whether the data exchange between the LVDS DDR and the main chip is bad; Screen, if it is confirmed that the logic board is broken, maintenance ideas: Check whether the 5V to 3.3V regulator block (AIC1084) of the driver board has power supply output. → Screen driver board fuse (F) - 3.3V → DC-DC conversion circuit → negative Pressure forming IC (-7V) → row and column driver IC. Logic board IC damage common problems: AAT1101A, M150XN05---white screen, dim boot image, etc. AAT1164, M170EG01---white screen after a period of time, shutdown and then restart White screen again for a while AAT1343 --- white screen, flower screen, vertical bars, etc. at startup AD8567 --- white screen TFT LCD screen manufacturer, LCD for Samsung display manufacturer, mobile phone LCD screen manufacturer.

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