A friend met a problem of LCD. It’s a black screen, but he found there’s signal and sound, and the master worked normally. He restarted the screen and found it works. A short time later, black screen again. All such as progress in it were ok as well as signal light.
Let’s analyze it in two aspects.
First, black screen, guiding light (green light or blue light) ok. It may cause by:
- The last stage of high voltage inverter circuit or the components for power supply involves in big generating capacity of heat and works for too long time, which makes cold joint.
- The circuit of backlight is with something wrong. In the circuit, coil for setting up voltage breaks easily. It’s usually bad connection.
Second, black screen, guiding light failed (it looks like no power to LCD). It may cause by:
- The thermal stability of switching tube in switch power is bad or basis components are cold joint.
- The thermal stability of voltage-regulator tube is bad. The S-pole of switching tube is to the voltage-regulator tube in ground.
- The resistor of S-pole is cold joint or damaged.