LED display module common problems maintenance daqo

Time:2018-11-29 Views:993

1. The whole LED display module is not bright: no power supply is connected;Input line interpolation;Inversion of input and output;The positive and negative poles of the power supply are connected in reverse.

2. The module is not bright and the transmission is normal: the protection circuit damage solution can short-circuit the 4th and 5th feet of 74HC138.

3. One of the three lines of the module is not bright: 4953 damage (is one of the damage).

4. The module is on one line at A time: for the problem of signal A, please check whether 74HC245 and 74HC138 have virtual welding;We can use a multimeter to determine whether the first pin voltage of 74HC138 is equal to about 2.5v. If 74HC138 is replaced,Carefully measure the path of ICA signal in the gold needle belt.

5. The module is two lines apart and two lines are on: for the problem of signal B, please check whether there is virtual welding between 74HC245 and 74HC138;The multimeter can be used to determine whether the second pin voltage of 74HC138 is equal to about 2.5v. If 74HC138 is replaced,Carefully measure the path of ICA signal in the gold needle belt.

6. The upper half module is normal and the lower half module is all on or off: if this is the case with the T08A interface, it is necessary to check whether the DR data signal of 8 lines is on the channel. If it is normal, replace 74HC245 first; if it is not, replace the first 74HC595.

7. STB and CLK signals of the upper part and the lower part of the module are common, and the data are separated (if it is T12 interface, there is one data).If the T08A board is checked, the upper and lower half boards should be checked separately.

8. If one of the lamps in the module is not on: check whether there is virtual welding and replace the lamp tube.

9. There are 4 lamps standing on end that are not on: first, check whether 74HC595 has false welding;The second replacement 74HC595;Third, replace the lamp tube.

10. Among the 4 vertical lamps, 3 are not on, and 1 is normal: replace the normal lamp tube.

11. If the module does not display normally from the middle or other positions in the future, check the condition of data signal path;Replace the 74HC595 of the last normal display control light;If not, replace the 74HC595 of the first lamp that displays abnormal control.Each 74HC595 controls 8 points wide *4 points high lamp tubes.74HC595 is connected in series by DR data signals which means that the DR signal goes from the 14th foot of 74HC595 to the 9th foot of the next slice to the 14th foot of 74HC595 to the last 74HC595.

12. Sometimes in the process of debugging the whole screen, the display of the front module to the back module is abnormal, and the general fault is that the wiring is not inserted or damaged;You can also use a slightly longer line arrangement to insert the line arrangement of the module being checked below into the abnormal module above to see how it is displayed, or you can connect the output of the normal module in front of the abnormal part above to the output of the normal module in the next row to see how it is displayed.