( 1 ) a power failure. This should be a very simple fault , common in the general liquid crystal display unit extension external power supply and two , some outside the machine . Whichever power , its structure is simpler than CRT monitors power more, the general vulnerability of some small components, such as fuses , rectifier bridge , 300V filter capacitor, the power switch, power management IC, the output diode rectifier , filter capacitors.

 

( 2 ) driver board power regulator circuit failure. Driver board or burn insurance regulator chip fails, there is part of the machine is the built-in switching power supply , the output of two power supplies, one group is SV, for signal processing , in addition to providing a high voltage is 12V Plate backlight , if switching power supply part of the circuit failure may result in the two groups had no power output , first check 12V voltage is normal , followed by Charles 5V voltage is normal , because the a / D driver board MCU chip operating voltage is 5V, so they can not find the machine when the fault , first with a multimeter to measure voltage of 5V , or if there is no voltage 5V 5V voltage becomes low, then a power circuit input stage may be a problem , that is to convert 12V to 5V power supply section of a problem, this failure is common, check whether the regulator block open welding or damaged. Another possibility is 5V load increased , the 5V voltage is pulled low , another way that the level of the signal processing circuit is a problem, there are parts of the circuit is damaged , causing the load increased, the 5V voltage is pulled low after the issue of the level component after each investigation , replace faulty components out , 5V can be restored to normal , the fault will be solved .

 

(3) MCU failure. Often the case 5V voltage returns to normal after experiencing can not boot up normally , this situation has many causes , one is being washed away MCU program may lead to boot, there is the MCU itself is damaged , such as MCU 's I / O port is damaged, so MCU can not scan button, encounter this failure caused by the MCU to find a hardware problem is of no use , even if you change the MCU can not solve the problem because the MCU is the need for programming and writing code , unless you can write a program to buy the MCU, but often the price is hard to accept. So in most cases only with generic substitution driver board A / D.