The most common fault of the power supply board is that there is no drive voltage output or the drive voltage is too low, resulting in a black screen (black screen means that the entire screen is not bright, or there is sound or no sound). When tested, it can be found that the VS drive voltage has dropped significantly, and the VSC drive voltage has dropped to about 0V.
In the actual maintenance, there is no need to bring fake load, you can test the machine, so the maintenance will be very convenient. When we suspect that there is a problem with the power board, we can unplug all the plugs of the entire power board assembly, remove the power board assembly, short circuit the CN802 (or CN9004) socket on the power board from the left third, fourth pin, and then give the power supply to the power board
If the power board parts are good, then after the power on, all of its sockets will output and the label on the screen, printed on the board the same voltage (there is a certain deviation, but the deviation value is very small), as long as there is a voltage or a group of voltage is not the same, then the power board parts are bad.
If the X driver board of the screen is broken, the following faults may occur: 1, the image is very dark or has no contrast or poor layering; 2 There may also be a black screen; 3. Colored patches on the image. When the X driver board is suspected to be bad, the board can be removed from the circuit, if the X driver board is removed, the image is almost unchanged, that is, the X driver board is installed and not installed.
When they are almost the same, the X driver board may be bad. Or you can replace it with a good X driver board. Whether the safety on the X drive board (indicating the location of the safety at this time) is burned out can also be a basis for whether it is damaged.
If the Y drive circuit board of the screen is broken, the following fault phenomena may occur: 1, black screen; 2. Black screen on the top half or black screen on the bottom half; 3, flower screen (image chaos); 4, horizontal bright line or black line or bright band or black band; 5 The upper or lower part of the screen is on. 6, burn Y upper and lower site selection circuit board. Whether the insurance on the drive board (indicating the location of the insurance at this time) is burned out can also be a basis for whether it is damaged.