This is a should be said to be very simple fault, the general liquid crystal display extension power and external power supply two, the machine outside the common some. Regardless of the kind of power, Character LCD Display its structure is much simpler than the power of the crt monitor, and the vulnerability is generally a small component, like a fuse, a rectifier bridge, Character LCD Display a 300V filter capacitor, a power switch, a power management IC, a rectified output diode, Capacitance and so on. Power board commonly used ic: 6841 203d06, Character LCD Display these commonly used pmw chip in my professional LCD accessories shop can buy.
Drive board burn insurance or regulator chip failure, some of the machine is the built-in switching power supply, the output of two power supply, one group is 5V, for signal processing, Character LCD Display the other group is 12V to provide high-pressure point backlight, if Switching power supply part of the circuit there will be a failure may lead to two sets of power are not output. Check 12V voltage normal no, Character LCD Display followed by check 5V voltage normal No, because the A / D driver board MCU chip operating voltage is 5V, so find open Not a machine failure, first with a multimeter to measure 5V voltage, if there is no 5V voltage or 5V voltage becomes very low, then one may be the power supply circuit input level there is a problem, that is 12V to 5V power supply part of the Problem, this fault is very common, Character LCD Display check the 5-side regulator block (common models 8050SD-LM2596-AIC15-01, etc.).
Another possibility is that the load of 5V increased, the 5V voltage pulled very low, Character LCD Display for a saying that is, after the signal processing circuit is a problem, some of the circuit damage, causing the load increased, the 5V voltage pull Very low, one by one after the investigation of the components of the problem, replace the failure of the components, the 5V can return to normal, the fault is generally resolved, Character LCD Display but also often encountered 5V voltage returned to normal after the normal boot, this situation also Kind of reasons, on the one hand the MCU program is washed out may lead to no boot, there is the MCU itself is damaged, for example, MCU I / O port damage, so that MCU can not scan the key, encountered by the MCU caused by the failure , Character LCD Display To find the hardware problem is useless, even if you change the MCU can not solve the problem, because the MCU is the need to write and write code, no way to find the original AD driver board replacement case, Character LCD Display we can only use the general A / D driver board replacement, such as: 151D or 161B and so on.
(Fuse F) and 3V or 5V switching voltage is normal.If the MCU problem is not due to the output switch control voltage, you can directly extract the 3-end stability of the power supply circuit, Character LCD Display Bump of the bright line fault is generally connected to the LCD screen on the cable out of the problem or a row and column driver IC damage.
Dark line is generally the screen of the body of leakage, or TAB flexible board connection open the above two questions is basically to the machine sentenced to death, Character LCD Display and no maintenance value, because the price of a screen is too high. (Guangzhou has a special replacement chip, the charges are high, the repair rate is also high).