LED advertising screen shows a row of all bright red
Author:Qiao Ling Time:2021-10-09 16:48 Browse(845)
Troubleshooting of outdoor module of LED display screen (taking p10-1r as an example)
LED display outdoor module troubleshooting (take p10-1r as an example)
1. The whole board is not on: the board is not connected to the power supply; The input cable is inserted reversely; The input and output are reversed; The positive and negative poles of the power supply are connected reversely (the connection reversely will burn all ICs on the board).

LED advertising screen shows a row of all bright red


2. The board does not light up and the transmission is normal: the protection circuit is damaged. The solution can short circuit the fourth and fifth pins of 74HC138.
3. One line in every three lines does not light up: 4953 is damaged (one of them is damaged).

4. One line in every other line lights up: a signal problem.
please check whether 74hc245 and 74HC138 have false soldering; You can use a multimeter to measure whether the voltage of the first pin of 74HC138 is equal to about 2.5V. If so, replace 74HC138; Carefully measure the ICA signal pathway of gold needle belt.

5. Light up two lines every two lines: B signal problem.
please check whether 74hc245 and 74HC138 have false soldering; You can use a multimeter to measure whether the voltage of the second pin of 74HC138 is equal to about 2.5V. If so, replace 74HC138; Carefully measure the channel condition of ICA signal in the gold needle belt.

6. The upper half board is normal, and the lower half board is all on or off: if the t08a interface has this condition.
this is to check whether the Dr data signal in the next 8 lines is on the channel. If it is normal, first replace 74hc245, if it is not good, then replace the first 74HC595.
7, The data is separated (if it is T12 interface data, it is also one).
if the t08a board is the upper and lower half board, it should be checked separately.

8. If there is one lamp on the board that doesn't work: check for false soldering and replace the lamp tube.
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9. There are four vertical lights are not on: first, check whether 74HC595 has false welding; Second, replace 74HC595; Thirdly, replace the lamp tube.
10. Among the four vertical lamps, three are not working and one is normal: replace the normal lamp tube.

11. If the board displays abnormally from the middle or other position, check the data signal path; Replace the 74HC595 of the last normal display control lamp; If it is not ruled out to replace the 74HC595 controlled by the first lamp with abnormal display.
each 74HC595 controls eight light tubes wide and four light tubes high.
74HC595 is connected in series with Dr data signal, that is, the Dr signal is connected from the 14th pin of 74HC595 to the 9th pin of 74HC595, from the 14th pin of the next 74HC595 to the last 74HC595. For example, the Dr data of this board is amplified from gold needle to 74hc345 to ur1 to UR2 to UR3 Until ur8 to output gold needle.

12. Sometimes during debugging the whole screen, the display from the front module to the back module is abnormal.
the general fault is that the cable is not plugged in or damaged; You can also use a slightly longer cable to plug the module under investigation into the abnormal module above to see how it is displayed. You can also connect the output of the normal module in front of the abnormal part above to the next row of modules to see how it is displayed, To judge which module is wrong.
note: the maintenance of other models is consistent, and the principle is the same. It's better to send a picture.
in this way, we can correctly judge.
Yikuo technology.
ten years of focusing on LED display control system,
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