This article analyzes and introduces Samsung screens, Chi Mei and other screens. It mainly explains the function and composition of the LCD Panel PCB, the circuit introduction of the LCD Panel PCB (T-CON board), how to identify the representative symbols of the LCD screens of various manufacturers, and the common problems on the LCD Panel PCB. Analysis, analysis of maintenance ideas for the LCD Panel PCB part and analysis of maintenance cases. 1. The role and composition of the LCD Panel PCB The information transmission between the main board and the screen body mainly includes the T-CON circuit, the LCD Panel PCB and the COF. The latter two are the signal link lines, which are the link between the OC and the PCB, so Focus on the principle and maintenance of T-CON circuit. According to the different manufacturer’s screen design, it mainly includes the following forms:
1. Separate T-CON board circuit
This is a traditional circuit combination form, a single edge strip is used by most manufacturers, and the failure rate is also the highest, especially for LG’s edge strips, as long as the water enters, the note must be replaced, and the COF will be damaged in serious cases. The LVDS signal generated by the main board is sent to the TCON board for processing and conversion into various control signals (STV, CKV, STH, CKH, POL) and image data signals (RSDS) required. Add to the OC in parallel to present the image.
2. The integrated circuit of the LCD Panel PCB and T-CON board
This is also the traditional circuit combination form, the control method is the same as above, but without a separate T-CON board, the maintenance factor is increased. It is especially important to check several main voltages during maintenance: VGH, VGL, VCOM, etc.
3. High-voltage board, T-CON board and LCD Panel PCB are integrated
4. This machine is less, Haier’s T315XW06 V5 OC uses this form
STV, CKV, STH, CKH, POL and image data signal (RSDS) to the LCD Panel PCB, generally use flat cable to enter the LCD Panel PCB. Many of the current integrated boards use this form, which brings inconvenience to maintenance.
Analysis of common problems on the LCD Panel PCB
The faults in the LCD Panel PCB are mainly manifested as: black screen, gray screen, blurred screen, vertical lines on the screen, vertical strips, etc.The main cause of the above-mentioned faults is caused by water in the LCD Panel PCB!
A. Causes of water ingress in the edge strips: Traditional CRT TVs are made of the entire glass cone with no connectors around. The current LCD screens use TAB elements, components, and COF to connect with the PCB board.The user still wipes the screen with a wet cloth like CRT, it is easy to get water in, especially when the LG screen LCD Panel PCB is inverted , The LCD Panel PCB is below, the failure rate is particularly high. As long as the water enters the LCD Panel PCB, it will corrode and seriously burn out the COF and OC. Because the user’s home is too tightly sealed and poorly ventilated in winter, it is easy to produce water vapor under the action of heating, which flows to the side along the screen On the board. In summer, under the drive of air conditioning, it is easy to cause water in the edge strips. Especially in the south, it is wet and humid, and the failure rate of the edge strips is higher. Household cleaning is also an important link that causes water to enter the LCD Panel PCB. There are also reasons such as children playing with water guns and installing TVs under the air conditioner, etc., which may cause water to enter the screen.
The faults in the LCD Panel PCB are mainly manifested as: black screen, gray screen, blurred screen, vertical lines on the screen, vertical strips, etc.The main cause of the above-mentioned faults is caused by water in the LCD Panel PCB!
A. Causes of water ingress in the edge strips: Traditional CRT TVs are made of the entire glass cone with no connectors around. The current LCD screens use TAB elements, components, and COF to connect with the PCB board.The user still wipes the screen with a wet cloth like CRT, it is easy to get water in, especially when the LG screen LCD Panel PCB is inverted , The LCD Panel PCB is below, the failure rate is particularly high. As long as the water enters the LCD Panel PCB, it will corrode and seriously burn out the COF and OC. Because the user’s home is too tightly sealed and poorly ventilated in winter, it is easy to produce water vapor under the action of heating, which flows to the side along the screen On the board. In summer, under the drive of air conditioning, it is easy to cause water in the edge strips. Especially in the south, it is wet and humid, and the failure rate of the edge strips is higher. Household cleaning is also an important link that causes water to enter the LCD Panel PCB. There are also reasons such as children playing with water guns and installing TVs under the air conditioner, etc., which may cause water to enter the screen.
The maintenance idea of the LCD Panel PCB part analyzes the gray screen, black screen or abnormal screen light-emitting maintenance methods: when the LCD screen has the edge strips, the main manifestations are the following situations: 1. The TV can be watched normally, but occasionally the grating side is bad. The phenomenon can be normal in an instant, and it is generally difficult to find. 2. The left or right grating appears on the TV screen. .3. The backlight is bright and the screen is not bright. Maintenance method: For the fault that the backlight is bright and the screen is not bright, you should first measure whether the logic board LVDS power supply 12 volts is normal. There are two situations at this time: (1) Normal. (2) The fuse has blown. If 12 volts is normal, you should measure the relevant voltages such as VCOMVGH, VGL, and focus on measuring the output voltage VG1-VG21. If it is still abnormal, the logic board is damaged. If it is normal, there is no doubt that water has entered the LCD Panel PCB. For the open circuit fault of the fuse on the logic board, it is not allowed to replace the fuse or directly short-circuit with a wire. The resistance value of the two ends of the fuse to the ground should be measured. If there is a short-circuit to ground, please check the cause. If the resistance to ground is large, it means that there is no short-circuit problem. You should disconnect the flexible cable between the logic board and the edge strip and replace the fuse. If it is normal at 12 volts, it means the LCD screen Water in. At this time, you can connect the two flexible cables from the logic board to the LCD Panel PCB only one way to determine the position of the water inlet.
