|
|
|
|
资料中心
|
| 一些常见液晶屏维修问题汇总 |
| 发布日期：2020-2-18 浏览次数：1141 [返回上一页] |
|
|
在我们的生活中，液晶屏无处不在。液晶屏在使用的过程中，会出现问题，那么要维修液晶屏就要学会判断是那一部分有问题!下面我们以液晶电视为例，来讲讲液晶屏常见的故障及部位的判断。
1、开机出现无象无音,电源灯闪一下变成常亮,屏幕在开机瞬间闪一下白光.此故障多为背光驱动板损坏.不过在维修中也遇见过是屏内的灯管损坏的。
2、出现开机一个时后花屏,音正常.此现象第一个是数字板不良(过孔不通或IC接触不好).第二是机内连线接触不好。
3、开机三无,电源灯不亮.第一个是电源板坏,第二个是CPU部分工作不正常。
4、灯闪不能开机，CPU总线工作不正常或开机程序IC(BIOS)不良,"BIOS"IC和CPU之间接触不良。
液晶电视机保养
1、温度高
液晶电视不外乎墙挂和座架式两种摆放方式，但相同机型和购买时间相同的机器，挂墙的机器比座式的故障几率大，而且相同故障也早出1-2年，这样看来，是和温度有关的，这种情况下，给修过的机器会装两个电脑风扇，以保证在保修期内不会因温度高而返修。
2、抗腐蚀性
歌厅，靠近厨房的机器比其他的机器故障率大，而且它们的毛病都来源于接插件之间的金属表面的腐蚀，甚至还会导致双面板的铜眼腐蚀，产生这种现象的源头当然是空气质量问题了，对于这种情况的维修，采用用导热硅脂密封又不影响散热的方法。当然接插件的金属要用橡皮搽搽干净。
3、出现黑点
几乎所有的液晶屏都会出现黑带，亮线的问题，修这个故障第一要有维修条件，维修完成后尽量用导热硅脂涂多点在COF的模组IC上。因为这个问题也是温度引起。
常见接触到的机器和故障现象和排除方法
1、液晶屏的问题(黑带，亮线)是最多的了，这种情况一般在没有维修条件下是做不了的，只有依靠有技术和维修条件的了。
2、LG V6 V7的屏组件的缓冲板是常坏件现象是满屏杂点，也有些是满屏有规律的竖条，这种故障可以更换一对缓冲板(就算一边坏，也是买一对。人家不会卖单个给你)或者测量出哪一块IC坏，更换就可以了。
3、不管哪种液晶屏，Y板是在PDP机器里面坏的几率占第二的了，它损坏后的现象一般是花屏，满屏彩点，或者因短路而造成电源保护，VS或VA电压瞬间有，但达不到屏上所表电压值。
4、X板也是PDP机器里的常坏组件，其表现为开机保护(富士通屏居多)，和亮度暗。
5、逻辑板的故障率也不低，在PDP LCD里都比较常见，它的表现多为屏有光，但会出现无字符，无图象，或者图象无规则乱彩，缺色，负像等。有的还不能开机。
6、LCD多见的故障是液晶屏上的问题了，暗带，线条，是最常见的，这些基本可以归纳液晶屏问题，有些要有维修条件才能修，有些是因为温度高，导致COF和液晶屏连接点的ACF脱离。这种现象可以用平头烙铁下面垫层隔热介质烫的方法修复。
7、LCD机器中，屏组件逆变电路(高压板)是故障多发件，表现为开机有光，但一会就无光，但有声音，(SHARP)除外，但光管老化和损坏都会导致高压板保护，判断光管还是高压板本身坏的方法是，取消高压板上的均值比较反馈电路。
8、很多朋友多问SHARP的LCD怎么维修，其实和普通LCD差不多，进入维修菜单后，可以看到出错项那里有故障代码，有些直接把代码清零，有些就要维修对应的故障部位了。
液晶电视背光灯常见故障判断
1、背光灯在交流开机瞬间液晶屏幕亮一下就熄灭，此时，伴音，遥控，面板按键控制功能均正常。
此种现象为背光灯电路保护所致，原因多为背光灯升压板供电异常。对于CCFL背光源电路，如果某一个背光灯管开路(常见为背光灯升压板上的灯管插座开焊或插座未插紧所导致的电路保护)或某根灯管断裂均可造成上述故障。
2、背光灯开关机无变化，伴音，遥控，面板按键控制均正常。
此故障需检测以下几个工作条件：1)，背光源升压板电路的供电，常见大屏幕为24伏，极少数用120伏，小屏幕一般为12伏;2)，CPU控制电路输出的背光灯升压板振荡器工作的开关控制信号，常见为高电平启动，多为3V—5V灯管点亮控制信号。如果上述工作条件均具备，则可以代换背光灯升压板，如果代换背光灯升压板后故障如初，多为液晶屏组件中的背光灯管损坏。
3、背光灯时亮时不亮。
常见为背光灯升压板的灯管插座与灯管接触不良，背光灯供电高或低。实际维修中，24V供电用数字表测量不应该有1V的误差(电源板上输出的24V电压无论是空载还是带载都应该稳定)。
1. When the machine is turned on, there is no image or sound, the power light flashes to be normally on, and the screen flashes white at the moment of turning on. This fault is mostly caused by the damage of the backlight drive board. However, during the maintenance, it was also found that the light tube in the screen was damaged.
2. When the machine starts for one time, the screen will turn on and the sound will be normal. The first one is that the digital board is not good (the vias are not connected or the IC is not in good contact). The second one is that the wiring inside the machine is not in good contact.
3. The first is that the power board is broken, and the second is that the CPU is not working properly.
4. The light flashes, the CPU bus does not work properly or the power on program IC (BIOS) is poor, and the contact between bios IC and CPU is poor.
LCD TV maintenance
1. High temperature
LCD TV is no more than two ways of placing: wall mounted and pedestal mounted. However, for the same machine type and purchase time, the failure probability of wall mounted machine is higher than that of pedestal mounted machine, and the same failure occurs 1-2 years earlier. In this case, the repaired machine will be equipped with two computer fans to ensure that it will not be repaired due to high temperature within the warranty period.
2. Corrosion resistance
The failure rate of the machines near the kitchen in the concert hall is higher than that of other machines, and their failures are all caused by the corrosion of the metal surface between the connectors, and even the copper eye corrosion of the double-sided board. Of course, the source of this phenomenon is the air quality problem. For the maintenance of this situation, the method of sealing with thermal conductive silicone grease does not affect the heat dissipation is adopted. Of course, the metal of the connector should be rubbed clean.
3. Black spots appear
Almost all LCD screens will have problems of black tape and bright wire. The first thing to fix this problem is to have maintenance conditions. After the maintenance, try to coat more points on the module IC of COF with thermal conductive silicone grease. Because this problem is also caused by temperature.
Common contact with machines and troubleshooting
1. The LCD screen has the most problems (black tape, bright line). In this case, it can't be done without maintenance, only depending on the technology and maintenance conditions.
2. The buffer board of LG V6 V7's screen components is often broken, which is full of screen clutter, and some are full screen regular vertical bars. This kind of fault can replace a pair of buffer boards (even if one side is broken, it is also a pair to buy). They won't sell you a single IC) or measure which IC is broken, just replace it.
3. No matter what kind of LCD screen, y board is the second most likely to be damaged in the PDP machine. After it is damaged, the phenomenon is generally flower screen, full screen color dots, or power supply protection caused by short circuit. The vs or VA voltage is instantaneous, but the voltage value on the screen cannot be reached.
4. The X-board is also a frequently broken component in the PDP machine, which is represented by power on Protection (Fujitsu screen) and dark brightness.
5. The failure rate of logic board is not low, which is common in PDP LCD. Its performance is mostly that there is light on the screen, but there will be no character, no image, or irregular color disorder, lack of color, negative image, etc. Some can't be turned on yet.
6. The common failures of LCD are the problems on LCD screen. Dark band and line are the most common. These problems can be summarized basically. Some can only be repaired under maintenance conditions. Some are due to the high temperature, which leads to the separation of COF and ACF at the connection point of LCD screen. This kind of phenomenon can be repaired by scalding the underlayer heat insulation medium under the flat head soldering iron.
7. In LCD machine, the inverter circuit of screen assembly (high voltage board) is a fault prone part, which shows that there is light when starting up, but there is no light for a while, except for sound (sharp), but the aging and damage of light tube will lead to the protection of high voltage board. The way to judge whether the light tube or the high voltage board itself is to cancel the mean comparison feedback circuit on the high voltage board.
8. Many friends often ask how to repair Sharp's LCD. In fact, it is similar to ordinary LCD. After entering the repair menu, you can see that there is a fault code in the error item. Some of them directly clear the code, and some of them are about to repair the corresponding fault parts.
Common fault judgment of LCD TV backlight
1. The backlight goes out when the LCD screen lights up at the moment of AC power on. At this time, the functions of sound, remote control and panel key control are normal.
This phenomenon is caused by the protection of backlight circuit, and the reason is that the power supply of backlight booster board is abnormal. For CCFL backlight circuit, if a backlight tube is open circuit (usually caused by the open welding of the light tube socket on the backlight booster board or the circuit protection caused by the socket not plugged tightly) or a lamp tube is broken, the above faults can be caused.
2. There is no change in backlight switch, sound, remote control and panel key control are normal.
This fault needs to detect the following working conditions: 1) the power supply of the backlight booster circuit, the common large screen is 24 V, very few use 120 V, and the small screen is 12 V; 2) the switch control signal of the backlight booster oscillator output by the CPU control circuit, the common one is high-level start, most of which is 3v-5v light tube lighting control signal. If the above working conditions are met, the backlight booster can be replaced. If the backlight booster fails as usual after replacement, the backlight tube in the LCD module is mostly damaged.
3. When the backlight is on, it is not on.
It is common for the poor contact between the lamp socket of the backlight booster board and the lamp, and the power supply of the backlight is high or low. In the actual maintenance, there should be no error of 1V in the measurement of 24V power supply digital meter (the 24V voltage output on the power board should be no-load or on load
|
|
|
|
