19-inch LG LCD monitor boot black screen fault repair example - appliance repair - Huaqiang electronic network

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Repairing a LG19-inch LCD monitor, less than two years, there is a black screen failure (occasionally, sometimes it can be normal for a few hours, most of the time it is black). According to my experience in repairing LCD, I moved within two years. If the machine is in a black screen, the fault is mostly caused by the de-soldering of the connection between the lamp and the high-voltage line!
Do not talk nonsense, began to carry out on-site surgical operations, opened the cover, first saw the backlight integrated board is still shiny, all components are still in adolescence, in order to further determine my judgment is correct or take a board with enough power for generation Change, although the power is sufficient, but from the circuit design, component materials, electrical parameters must be somewhat different, here I want to explain that * often some of the lamps are aging, on the original board It’s black screen, but when you put it on the new board, it’s not good, it’s not black, you can even stick to it for half a day, don’t be happy, don’t be happy, he will still show you why it will appear in a few days. This situation, I have already said above, the circuit design, component materials, electrical parameters are somewhat different.
I changed the board and changed it. I really didn't expect it. It was not black for a long time. Fortunately, my experience is a little bit. You are not black. I still have to carefully check the screen that I am "very careful". And put the screen in a "safe place" and then remove the lamp holder from the light guide plate. The inspection found that one of the two pairs of lamps had a blackening phenomenon, and finally put The source of the disease is found. Before the judgment, the eight-nine-nine is not separated. The next step is to change the lamp. I am basically changing the lamp. I won’t say that if I have the problem, I will change it. The lamp must be wiped out. In case of trouble...
After changing the lights, don't rush to install the screen, connect the original board to the test machine, don't try to know how to start a shock, huh, of course, it is normal.......
Then carefully put the screen well, and then install the equipment, then the next step is of course to smoke a cup of tea, my God! A cigarette is not black. Well, what's going on, what is going on in the end, I haven't done anything wrong these days, why should I do this to me, why should I have a black screen, I am sure that the one board is good, is it that I change the lamp? I didn’t pretend it, it’s impossible, I tried it when I didn’t install the screen, I’m so sad....
After the heartache, I have to check it. The problem with the black screen is nothing more than the 12V power supply---the high-voltage part---the control board part, the lamp part, is there a problem? But I have clearly checked the detection. Ah, it’s hard to be a high-voltage high-voltage line to earth leakage. I hate it at this time, hate myself for not killing the high-voltage line. (Everyone knows that the screen is annoying, that is risky.) The method had to continue to dismantle the screen for the second time, and replaced the high-voltage line. After the change, the screen was not installed and the machine was normal. After that, another screen was installed, and I thought it was finally settled. I can suck a cigarette well. Who knows, after his mother's installation, there is a black screen failure. God is unfair. Can a young heart withstand such torture? I am very annoyed when I remove the screen. After being demolished twice, it is still the same, I really took LG!
Hate to hate, the revolution has not been successful, comrades still have to work hard, this situation makes me unsuccessful for a long time, I finally found out that I hate it... There, there, who is the real murderer! I caught it and I have to shoot it.......Details, details, it turns out that after I touched the screen line, the black screen will appear. Why is this, is it a logic board?
The logic board is a kind of fault that will often affect the black screen. It really makes Laozi's unreasonable solution. It is indeed a logical fault that has made me unforgettable!
In the end, I locked the scope on the logic board. After scanning through the magnifying glass, I didn't find any vision. In the end, my eyes were so bad. I heard unusual strange sounds. What kind of sound is so ugly and so Unfamiliar; there is something on the logic board that can make this sound, right, only it is the "inductance", kill me too...
The logic board is powered by 5V. 5V supplies power to the signal chip AAT1168B through this inductor. The sound is emitted from this inductor. This sound must be abnormal. Why is it not normal? Because the inductor core is cracked a bit, it cracks a little. If the magnetic sense changes, the current will change when the current is changed. (Please note that this inductor cannot be directly connected. It is not a general inductance. If you connect directly, you should smoke it. Rolling), finally I found the same replacement on the used board, the ghostly voice is gone forever, and finally solve the problem completely, this machine repairs the paragraph, this road should not be faulty Will affect the black screen, this is still waiting for me to analyze it in the future)