I believe those who have made LCD panels have a certain level of understanding of logic boards. A good logic board is an indispensable part of an outdoor LCD advertising machine. To have outdoor display characteristics in advertising machines, logic board selection is essential. Good outdoor high brightness LCD advertising machines are equipped with a good logic electronic board.
The logic board is mainly composed of two parts of circuits: a format converter and a DC/DC converter. The analysis and maintenance process of these two fault examples shows that most of the faults in the logic board are in the DC/DC converter circuit. For repairing this part of the circuit, it is not difficult to understand its circuit structure. The key point is to be familiar with the timing control process of its DC/DC circuit and the generation of 5 large voltages. The general reason for a white screen is that a resistor on the logic board is burned out by current, which causes the outdoor advertising machine to not light up.
When checking the white screen, be sure to check if the logic board is intact. Check if the entire machine can start normally, the duration of the screen turning on, and the white screen appearing after turning on, as well as whether the accompanying sound and other functions of the machine are normal, and determine whether the fault is on the logic board. Check the power supply of each circuit on the logic board, check that there is no voltage at the VGHP point, and ensure that the VGHP voltage is stable at around 19.5V. If the voltage is abnormal, it can be immediately confirmed that it is caused by VGHP voltage. If the resistance at the VGHP output terminal is normal, it is a problem with capacitor CP19. In general, white screens are caused by unstable VGAH voltage. In the process of maintenance practice, in addition to VGHP, there is also capacitor CP19. These two electronic components are not expensive yet, and the components used on the logic board are completely available in the market at a very low price.
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