How to repair the LED display screen _LED screen repair books?

by:Xinyao LCD     2020-04-01
How to maintenance problems LED display? Believe that after you saw this article displays appear small problems won't faze you. The fault analysis and processing solution to the problem of LED display: failure analysis for beginners is the most direct, the most effective method of deduction, the display is mainly has three big hardware: control card, unit board, switch power supply. First, we determine control card is good, you look at the first turn on the power supply, control card lamp is lit, if not bright look at check whether there is a 5 v power supply, if display screen can display content, as long as it can display content, control card display function is good; Then you search control card with control card software, if we can find that illustrate the function of the control card to send content is good, if not find, did you see the communication lines connected, if ok, may be there is something wrong with the card. As long as the two function is good, the control card is ok, otherwise will replace the control card. Secondly; Us to determine the power supply is good, if the power supply is broken, it will directly cause a few boards at the same time not bright or not normal, because a power control of several boards at the same time, also is your screen if it is in the same small area of a few boards don't display or not normal, you should consider whether the power supply is broken, is the most direct detection method with multimeter to dc voltage measurement output voltage whether in 4. 9 to 5. Between 5 v. If it is to be replaced the power supply. Finally: we want to determine unit board is good, display the output of the signal from a cell plate transferred to another line needle plate of the input signal, so there is a problem, a board that will cause behind it the whole row not bright or abnormal, so when there is something wrong with the display in a row, we should see this as a starting abnormal change the plate, or with long line will jump this board in the past, look at the back of the plate is displayed normally. A. There is something wrong with the output 1, check whether the line of the output interface to the signal output IC connection or short circuit. 2, test the output clock latch signal is normal. 3, test the last driver IC level between the output data is connected to the output interface of data mouth mouth or short circuit. If there is a mutual 4, output signal of short circuit or short circuit to ground. 5, check the output lines are in good condition. On a line or lines at dawn, detection 1 between 138 and 4953 lines or virtual welding, open circuits. The whole plate is not bright one, check whether the power supply and signal wire connection. 2, check whether the test card is to identify the interface, the red light flashing does not identify test card, check whether the lamp panel is power supply with test card, or light board interface has signal and short circuit identification interface. ( Smart card) 3, testing 74 hc245 presence of virtual short circuit welding, corresponding enabled (on 245 EN) Signal input and output whether foot virtual welding or short circuit to the other line. Note: check the power supply and can make ( EN) The signal. In oblique scan, A regularity of interlaced not bright display picture overlapping 1, check A, B, C, D if there is A disconnect between signal input port to 245 or virtual welding, short circuit. 2, testing 245 corresponding outputs A, B, C, D and whether or virtual welding, open circuits between 138. 3, test A, B, C, D between each signal is short circuit or A signal with A short circuit. Note: the main detecting ABCD line signal. According to chaos, but the output signal to the next board 1, 245 the corresponding normal STB latched output connected to the driver IC latch end whether or signal is short circuit to the other line. On 1, there is one or a few columns dawn on the module control pin in the column, whether measurement and drive IC ( 74HC595/TB62726、、、) Output terminal connection. Have a single point or single highlighting, or the entire line highlighting, and is not controlled, check whether the column 1 short circuit and power supply. 2, check whether the bank the positive short circuit and power supply. 3, replace the driver IC. According to chaos, the output is not normal 1, testing the clock CLK latch STB signal is short circuit. 2, test of 245 clock CLK input and output. 3, testing the clock signal is short circuit to the other line. Note: the main testing the clock with the latch signal. Showed a lack of color, 245 of the color of the data input and output. 2, test the color data signal is short circuit to the other line. 3, test the color of the driver IC level even data between whether there is open circuit or short circuit, virtual welding. Note: you can use voltage test is easy to find the problem, detecting data voltage is different from normal whether mouth, determine the fault zone. All bright there is a single point or multi-point ( Irregular) Don't light 1, find the corresponding control module whether foot measurement with our short circuit. 2, module or single lamp replacement. In the line scan, the two lines or a few lines ( Generally is a multiple of 2, regular) Light at the same time, detection 1 A, B, C, D whether short circuit between the signal. 2, test whether 4953 output with other output short circuit. L, all the LED not bright: total power did not open; Some LED not bright: switching power supply output polarity meet against or module connection with open circuit phenomenon; All LED dim: load the LED polarity meet the number too much or module; Part of LED dark and light bead fever: module wiring short circuit; LED brightness is not consistent: number too much load LED LED flashing: bad line contact; Insurance: burning module or wiring have short circuit phenomenon.
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