Drive board burn insurance or regulator chip failure, LCD Display some of the machine is the built-in switching power supply, the output of two power supply, LCD Display one group is 5V, for signal processing, 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. First check 12V voltage is normal, followed by check the 5V voltage is normal No, because the A / D driver board MCU chip operating voltage is 5V, LCD Display so find open Not a machine failure, first with a multimeter to measure the 5V voltage, if there is no 5V voltage or 5V voltage becomes very low, then a power supply circuit may be a level of the problem, that is 12V to 5V power supply part of the Problem, this fault is very common, check the 5-side regulator block (common models 8050SD-LM2596-AIC15-01, etc.).
Another possibility is that the load of 5V increased, LCD Display the 5V voltage pulled very low, 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 troubleshooting the components of the problem, replace the failure of the components, the 5V can return to normal, the fault is generally resolved, LCD Display but also often encountered 5V voltage returned to normal after the normal boot, this situation also Kind of cause, on the one hand is 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 , 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, 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 caused by the output switch control voltage, you can directly extract the 3-end stability of the power supply circuit, LCD Display (AIC1084) 3.3V instead of repair the idea of high-voltage board (power fuse ---- switch control tube ---- power management IC ---- push the hair tube - power switch - - FET conversion circuit (energy storage inductors, LCD Display rectifier) --- LC boost circuit (step-up transformer, boost capacitor) ------ coupling capacitor ---- lamp.
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 on the body of leakage, LCD Display or TAB flexible board connection open the above two problems is basically to the machine sentenced to death, 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).