Solutions of Common Failures of LED Display Screen | Part 1
Why does your display always fail? Have you checked these questions?
Common failure analysis of LED display screen
LED screen failure analysis is the most direct and effective method for beginners. The display screen is mainly composed of three main hardware: control card, unit plate, switch power supply.
First of all, let’s judge whether the control card is ok. You can turn on the power supply and control the indicator light. If you don’t see if there is a 5V power supply, the display screen can display the content, as long as the content is displayed, the control card displays the content function is good; Then you can look up the control card with the control card software. If it can be found, the function of the control card’s sending content is good. If you can’t find it, you can see if the communication line is connected. If you do, you may have a problem with the card. As long as these two functions are good, the control card is good, otherwise you will change the control card.
Second, we must judge whether the power supply is good. If the power is broken, it will directly cause a few panels to be unlit or abnormal, since a power supply is controlled by several panels at the same time. If your display is not normal on a few boards in the same small area, you should consider whether the power supply is broken. The most direct test method is to measure the output voltage between 4.9 ~ 5.5 V with a multimeter dc voltage, and if so, replace the power supply.
Finally, we need to determine whether the unit plate is good. The LED full-color display signal is transmitted from one unit plate to the input signal of another board, so a plate has a problem, which can cause the whole row to be unlit or abnormal. When there is a problem with the display screen, we should replace the plate with an abnormal start, or skip it with a long line, and see if the back panel is normal.
After this three-step failure analysis, it is possible to determine where the fault of LED display is. At the same time, it provides a good foundation for the failure of LED screen to provide a feasible solution.
Common failures of LED displays and solutions
After knowing the fault, users can solve the problem by themselves if they have certain maintenance knowledge, saving time and maintenance cost effectively. Here are some common troubleshooting methods.
Problem 1: there is a problem with the output
1) check whether the output interface to the signal output IC is connected or short-circuited.
2) it is not normal to detect the clock locked signal of export.
3) check whether the output data port of the final driver IC is connected to the data port of the output interface or not.
4) whether there is a short circuit or short circuit to the output signal.
5) check whether the output line is good.
Question 2: there are a few lines or a few lines in the light
1) test whether the line between 138 and 4953 is broken or false and short circuit.
Problem three: the whole edition is not bright
1) check whether the power supply and signal line are connected.
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 test card)
3) to detect whether the 74HC245 has the virtual soldering short circuit, and the corresponding enabling (EN) signal input to the output leg of the (EN) signal is not to be soldered or short-circuited to other lines. Note: main check power and enable (EN) signal.
Problem 4: when point-slope scanning, the regularity of the partition is not bright or the picture overlaps
1) check whether there is A broken line or virtual welding or short circuit between A, B, C and D signal input ports to 245.
2) check whether the output terminals of A, B, C, D and 138 of 245 are broken or virtual welded and short-circuited.
3) detect whether A, B, C, and D signals are short or short-circuited. Note: mainly detect ABCD line signal.
Problem 5: display chaos, but the signal to the next plate is normal
1) check whether the STB lock output of 245 is connected or the signal is short-circuited to other lines.
Problem six: single or single columns are highlighted or highlighted, and are not controlled
1) check if the column is short-circuited with the power.
2) check whether the bank has short circuit with the power supply.
3) replace the driver IC.
Problem 7: display chaos, output abnormal
1) check whether the clock CLK lock STB signal short circuit.
2) check whether the clock CLK of 245 has input or output.
3) check whether the clock signal shorted to other lines. Note: mainly detect the clock and lock signal.
Problem eight: show lack of color
1) check whether the data end of the 245 color has input/output.
2) check whether the data signal of the color is short-circuited to other lines.
3) check whether there is a circuit or short circuit or virtual welding of the level connecting data port between the driving IC of the color. Note: it is easier to find the problem by using the voltage detection method. The voltage of the test data port is different from the normal one, and the fault area is determined.
Problem nine: there is a single or more (irregular) light at all lights
1) find out whether the control foot measurement corresponding to this module is short-circuited with this line.
2) replace the module or single lamp.
Problem 10: when scanning, two or more lines are simultaneously lit
1) detect whether there is A short circuit between signals A, B, C and D.
2) detect whether the output end of 4953 is short circuit with other output terminals.
Question 11: all leds are not bright
1) the total power supply is not opened; Partial LED is not bright: switch power output wiring polarity connection or die – line connection has broken path phenomenon.
Question 12: all leds are dark
1) excessive number of load LED or polarity of module polarity; Part LED dimming and light bulb heating: short circuit of module wiring; LED brightness is inconsistent: overload LED is too many.
Question 13: LED flickers
1) bad contact; Fire insurance: short circuit at the module or terminal.