Overhaul a 32-inch LCD TV, the faulty gray screen has a sound. Open the cover and observe that the motherboard has local burnt, see the figure
The voltage of the upper screen of the 12V is measured as 0, and the burnt part is the screen power supply circuit. Test the motherboard line red line to ground resistance is normal, no short circuit. According to the user, the same fault occurred not long ago, and another maintenance department was replaced by a motherboard. This is not, it took no more than three months to burn again. It seems that it is not necessary to change the board rashly. There must be hidden faults. What is the source of this?
Observing the logic board did not see the same, take off the screen line at both ends of the test, did not see the cable between the touch
I didn’t see anything when I was scratching. Test each logic terminal, filter capacitor, and voltage regulator block of the logic board without short circuit. Oddly, it’s frustrating to connect the two ends of the screen line, and then measure the power supply end of the logic board. The resistance is zero! Haha, the fox tail is exposed.
Because the enemy is more concealed, in order not to stun the snake, scare the enemy, take a segmented compression encirclement. Gently unplug the motherboard's end screen cable and measure the motherboard plug-in resistance. Then measure the screen line and short circuit. Carefully disconnect the screen from the logic board, and the screen and logic board are not abnormal. Plug in the screen line and find that it is short-circuited when you lift the logic board end plug upwards. It is normal to release it or press it slightly. Ok, the problem is here.
When the socket is gently lifted, the screen power supply line and the socket iron collide, causing a short circuit to burn the motherboard. The solution is easy
Put the iron sheet up a bit, insert the screen line, and then shake the screen line everything is normal, change a new motherboard, delivery!
Such a hidden short-circuit fault, rare, must not be careless! If you change your board, you will lose a lot!
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