推荐回答(5个)
一、正常的供电电压
逻辑板的供电电压(俗称上屏电压)常见有+3.3V、+5V、+12V, 少数机为18V,这一电压来自信号板,与一只保险电阻或贴片保险相连。只有该电压正常,逻辑板才能正常工作。逻辑板供电电压的测试点一般有一保险电阻相连。
二、正确的LVDS信号
检修时一般可通过测量逻辑板LVDS信号输入端的直流电压来大致判断有无LVDS信号,正常值约在1V左右,当然具备示波器的、测试波形就更容易判断信号的有无以及畸变等信息。
三、正确的VGH、VGL、VDD、VDA(或VCC)电压
不同型号的逻辑板的VGH、VGL、VDD、VDA电压值各不相同,其中,VGH电压通常在18V-27V之间,VGL电压通常在负5.3V-6.3之间,VDD电压一般在15V左右,VDA或VCC电压一般为3.3V。 多数逻辑板均标有上述四个电压测试点。VDD、或VCC电压可能有多个值,一般通过测量TFT偏压电路外围电感或稳压块脚电压来判断。
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四、正确的液晶屏信号格式选择电压
LVDS信号格式有VESA格式和JEIDA格式两种。一半靠近LVDS插座会有2只选择LVDS格式的电阻,平根据屏的要求来选择其阻值,使格式选择端口的电压与屏对应。一般由0V、3.3V、5V、和12V几种。
五、正确的幁频选择电压
检修中注意部分液晶屏(如 奇美屏)设有幁频选择端口,以选择液屏的显示频率是50HZ或是60HZ,以适应输入信号的幁频。如果该端口的选择电压错误、屏的显示频率和输入信号的幁频不相同,会出现无显示的故障,请注意。
背光亮没有字符,说明高压板正常,有两种可能:1、测量主板屏供电,有无12v(就是很多线连接到屏上的)如果没有12v表示主板有问题,顺着12v电路走,基本上就是旁边那个八角贴片控制块坏了,2、如果有12v表示逻辑板坏了,修逻辑板需要的设备不知道你有没有。一般都是直接换屏的。
液晶电视上屏电压测试方法:屏线链接到逻辑板的接口就可以测试出来电视屏上电压。
液晶面板是决定液晶显示器亮度、对比度、色彩、可视角度的材料,液晶面板价格走势直接影响到液晶显示器的价格,液晶面板质量、技术的好坏关系到液晶显示器整体性能的高低。
液晶面板能否达到真彩显示的16.7M色彩,其含义是指在R.G.B(红绿蓝)三个色彩通道都具有在物理上显示256级灰阶的能力。产量、优劣及市场环境等多种因素都关系着液晶显示器自身的质量、价格和市场走向,因为一台液晶显示器其80%左右的成本都集中在了面板上。
TN面板
TN全称为Twisted
Nematic(扭曲向列型)面板,低廉的生产成本使TN成为了应用最广泛的入门级液晶面板,在市面上主流的中低端液晶显示器中被广泛使用。我们看到的TN面板多是改良型的TN+film,film即补偿膜,用于弥补TN面板可视角度的不足,改良的TN面板的可视角度都达到160°,当然这是厂商在对比度为10∶1的情况下测得的极限值,实际上在对比度下降到100:1时图像已经出现失真甚至偏色。
作为6Bit的面板,TN面板只能显示红/绿/蓝各64色,最大实际色彩仅有262144种,通过“抖动”技术可以使其获得超过1600万种色彩的表现能力,只能够显示0到252灰阶的三原色,所以最后得到的色彩显示数信息是16.2
M色,而不是我们通常所说的真彩色16.7M色;加上TN面板提高对比度的难度较大,直接暴露出来的问题就是色彩单薄,还原能力差,过渡不自然。
上屏供电一般为5V 或12V 一测便知 Ok 高压板能点亮说明不是高压板的问题及其控制电路的问题啦! 应该是主板
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