This phenomenon is usually the problem of the PCB

To troubleshoot, first of all have a certain understanding of the module, so that repair from the module in order to play a multiplier effect.
<1> troubleshooting prerequisites:
① assembled to master certain lcd module skills, mastered certain skills in troubleshooting, can be handy, reduce assembly problems.
② To constitute modules have a certain understanding. A module, in order to have good electrical display, shell, screen, zebra, PCB board must be designed, qualified raw materials in order to receive good results. Such as: zebra compression ratio enough, resulting in lack of planning, this situation is repeated assembly, reliability display lcd 16x2 does not work, then we should change the zebra.
③ To the assembled modules to the principles of the modules have some understanding of the problem so that after assembly of the module will be targeted. Such as: When on a PCB, chip pin control panel two SEG electrodes, once discovered missing two SEG symmetry appears on the module, it can be concluded that the problem of the PCB
Semi-deep half-light, do not walk, program exceptions, less of a screen or a few screen when not in tune, there are shadows, etc. This phenomenon is usually the problem of the PCB, you need to remove the PCB test PCB board. Reassembly with a good PCB board.