Shenzhen 86 LCD switchCardi Smart Technology asLCD moduleManufacturers for you to share the LCD screen general troubleshooting methods are as follows:

First, the composition of the LCD screen and common faults

LCD screen is generally composed of backlight board, logic board and display.

a. Backlight panel: supply of backlight sources

Access method:

1, black screen (backlight board light source is not bright), generally for the backlight board bad.

2, black screen (when the backlight flash on the black screen), generally also backlight plate bad.

Some LCD screens have a backlight plate on each side of the screen. Any one of the backlight board is not good, there will also be a black screen failure.

b. Logic board: convert the digital signal provided by the motherboard into a logical signal that controls the transmission of the LCD screen or blocks the transmission of light

Access method:

1, black screen (backlight plate bright), this kind of fault is generally bad logic board

2, the picture has noise or there are images of color spots. This kind of fault is generally bad logic board

C. Display: Control of light through or not to let light through (poor display does not repair)

Note:

The composition of the LCD screen is relatively simple, as long as the maintenance around the backlight plate and logic board to repair it. The fault range is determined by fault phenomenon analysis and repair replacement. Then carry out circuit repair.

Second, drive plate maintenance

A) The simple composition of the drive plate, generally by the power supply, high-voltage inverter, control circuit and protection circuit, such as several parts

Power supply circuit

The total power supply of the power supply circuit is due to the power supply of the TV, usually 12V (small screen) or 24V (large screen).

2) Black screen of the drive plate (backlight plate is not lit)

1. Black screen (backlight plate is not bright) most of the drive board power circuit failure, power circuit generally has more than one level of fuse. The fuse element number usually begins with F. See the following image in the repair of the most common generally mostly fuse open. Fuses are generally marked in the circuit, when the detection of fuse suffix, first measure after the stage there is no short circuit. If there is no short circuit in the rear stage. The fuse can be replaced directly and then the test machine is aging.

2. Some screens will have a voltage or voltage-sharing circuit for power supply. When servicing, check that the power supply to the control circuit is correct.

3) Black screen of the drive board (backlight plate flash black screen)

1. Backlight plate and other sources flash a black screen, generally for high-voltage inverter and protection circuit failure. In this fault, the high voltage inverter is damaged more, and the bad part can be determined by the comparative resistance measurement of multiple transformers.

2. Another is to protect the circuit fault, the protection circuit is generally at the upper and lower ends of the drive plate or the input of each transformer. Since there are no drawings, more than the use of comparative resistance measurement repair. Step-by-step determination of faulty components by the critical point resistance of different transformer protection circuits

Third, the maintenance of the logic board

The logic board is generally composed of power supply, signal conversion, signal caching circuit.

1. First of all, the power supply, because the logic board of the power supply voltage is low, generally below 5V, so the power supply circuit failure is less. However, in the repair or measure the power supply resistance or fuse. If there is an open power supply resistance or fuse, a black screen (backlit plate is on) will fail.

2. Signal conversion is generally done by an integrated circuit. If a black screen (backlit plate is bright), the power supply is likely to be the integrated circuit is bad.

3. Signal caching circuit, generally consists of one or two caches. If the cache is poor, there may be spot-like interference in the screen, similar to the mole-shaped screen.

4. Logic board due to low voltage, component fault is not common, whether it is a black screen or the screen has a mole-like interference, the most important is the circuit and connection normal. So the check of the line is particularly important. Lineing is prone to false welding or false connections due to how many pins are. Most fault check lines or reinsert it may be normal. Some line socket due to a few plug-in will appear virtual welding, welding can be.

Four. Note

LCD screen because there are no drawings and more delicate, so in the maintenance is best not to carry live maintenance, it is advisable to use resistance measurement repair method.

It is best to wear anti-static wrists during repairs, or wash your hands before repair, wiping your hands or bodies with a wet towel. Put the static electricity. To avoid unnecessary failures

Because it is difficult to find the components of the prototype number, in the replacement of components, try to use similar specifications of the components. In replacing the fuse, pay attention to the rated voltage and current of the fuse, do not use too much difference in the replacement, not to replace with a short route.