After the LCD screen is turned on, the displayed picture is all white, which is what we call the "white screen" phenomenon. How to solve it? We first check the screen cable. If the screen cable is in poor contact, just unplug it and plug it in again, or replace the screen cable with a new one. But in actual scenarios, it is more that the circuit board fails. This requires us to have a certain understanding of the internal structure of the LCD screen, otherwise the maintenance work will be impossible.
01
LCD-skærmens interne struktur
The common liquid crystal displays on the market are mostly composed of driver boards, power boards, high-voltage boards (many are designed together with the power boards), key panels, liquid crystal panels (including liquid crystal molecules, liquid crystal driver chips, color filters, polarizers and Light guide plate, backlight tube, etc.). The phenomenon of "white screen" is mainly related to the failure of the driver board and power board.
1. Strømkort
The function of the power board is to convert the 220V alternating current into direct current, and supply the driving board, high voltage board, liquid crystal panel and other work. If the power supply board is abnormally supplying power to other circuit boards, it will cause a "white screen" phenomenon.
2. Højspændingsplade
The high-voltage board mainly converts the DC power output by the power board into the high-frequency voltage AC power required for the startup and operation of the backlight tube. The normal working voltage of the high-voltage board is 12V, and the backlight tube needs a high-frequency voltage of 1500-1800V. But "white screen" means that the backlight tube is no problem, that is, the high-voltage board is not faulty.
3. Driverkort
The driving board mainly receives and processes the image signal sent from the outside, and sends the driving signal through the screen line to control the operation of the liquid crystal panel. Therefore, the failure of the driver board will also cause a "white screen".
02
Inspektionsrækkefølge
Kontroller først strømkortet: Brug et multimeter til at måle strømforsyningsspændingen på skærmkabelgrænsefladen. Hvis detekteringen viser, at strømforsyningskredsløbet er unormalt, er løsningen at kontrollere, om sikringsmodstanden eller sikringsinduktoren nær udgangsenden af skærmkablet er åben eller beskadiget. Hvis beskadiget, udskift de beskadigede komponenter;
Hvis testen viser, at strømforsyningskredsløbet er normalt, er det meget sandsynligt, at driverkortet er defekt. Derefter er det nødvendigt at kontrollere, om tidssignalerne og køresignalerne i LCD-panelets kørekredsløb er normale. Hvis det ikke er normalt, skal du kontrollere udgangssignalet, indgangssignalet og strømforsyningsspændingen for den chip, der genererer dette signal, for at afgøre, om driverchippen er beskadiget. Hvis den er beskadiget, skal du bare udskifte den.
