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电视机维修技术

电视机维修技术

电视机原理与维修

前言

随着科学技术的发展和人们文化物质生活水平的提高,家用电子产品越来越受到人们的欢迎,其中电视机是人们生活中不可缺少的组成部分。近几年来,新技术、新器件、新工艺的出现,使彩色电视机的性能和高新技术含量都有了很大的提高,而且不断有新的产品的问世,电视机市场出现了前所未有的活跃。市场热销的同时也给维修行业带来了许多新的问题,维修人员需要普及电视机的原理与维修方面的基础知识。学习电视机的维修首先要学懂电视机的原理,其次是了解常见故障与症状表现之间的关系,进而学会分析故障和排除故障。本文将着重描述电视机的原理和维修。

1. 电视机的原理

电视机的信号处理过程可以看作简单的电视机工作原理。

电视高频信号由天线接收后被送到调谐器中,在U/V调谐器中经过高放后与本机振荡信号混频,形成中频信号,其频带宽度为8MHz,包含图像中频信号和伴音中频信号。调谐器输出的中频信号经过滤波后输入到图像中频处理单元,在其中先将中频信号放大,然后对其进行视频检波,得到视频全电视信号和6.5MHz的第二伴音中频信号。视频全电视信号被分为两部分处理,一路经过6.5MHz带通滤波器,提取出6.5MHz的第二伴音中频信号,经伴音中放、鉴频器后得到伴音音频信号,最后经音频放大电路的放大,送到扬声器还原成声音;另一路经过6.5MHz陷波器,吸收6.5MHz的伴音信号,取出0,6MHz的全电视信号,它含有亮度信号、色度信号和行场同步信号及加在行同步上的色同步信号。全电视信号经4.43MHz陷波器,去掉视频信号的色度信号,输往亮度处理电路,得到亮度信号;经4.43MHz带

通滤波器,从视频信号中取出色度信号,输往色度处理电路,经解码后得到R-Y,G-Y,B-Y三个色差信号,再经短阵电路得到R、G、B三基色信号,送到显像管电路;经同步分离后去行、场扫描信号产生电路,视频全电视信号在同步分离电路中通过幅度鉴别分离出行同步信号和场同步信号,分别送到行、场振荡电路。振荡电路的频率和相位将在同步信号控制下,保持接收机行、场扫描的顺序与发射端相同,即实现同步。行、场扫描电路输出行、场偏转电流给偏转线圈,使显像管上形成光栅。

2. 电视机各部分的故障检修

2.1 电视机的整机构成

一台电视机主要由调谐器(高频头)、中频通道(视频检波、伴音解调)、音频电路、视频信号处理电路(亮度电路、色度解码电路)、行场偏转电路、行回扫变压器(含高压、副高压产生电路)、系统控制电路和开关电源等构成。

2.2 调谐器的故障检修

2.2.1 调谐器的作用

调谐器:调谐器是接收电视信号的电路,将天线接收的射频信号进行放大、变频。它的主要功能是选择电视频道,并将所选定频道的高频电视信号放大,然后与本振信号进行混频,输出中频信号。

2.2.2 调谐器的常见故障

调谐器如果出故障,最常见的收不到电视节目,不能锁定在某一频道上,图像上有明显雪花噪波,同时伴音噪声也变大,图像模糊或无色彩等。

引起上述症状的原因往往是调谐器本身不良,供电不良,调谐器外围电路损坏,中放电路提供的AGC电压或AFC电压不正常,或引线焊接不良等。

the neighbouring frequency transmission planning, the system can accommodate more than more than 80 TV channels, 2 reverse channels.

Taking into account the needs of e-commerce in the future, this system increase in backhaul bandwidth, take up to 4 channels. Wired TV distribution statistics following table: Wired TV information points distribution schedule-medical floor, rehabilitation floor, 1th, floor, 2nd, floor serial number a layer two layer three layer four layer five layer underground a layer underground two layer total medical floor 53 54 52 71 54 7 5 296 rehabilitation floor 7 5 5 4 4 2 27 2nd, floor 18 18 10 46 1th, floor-East floor 16 16 16 3 51 1th, floor-in the floor 21 15 12 5 53 1th, Floor-West floor 20 15 18 3 56 total 529 (3) information guide and the released system system used concentrated control, and unified management of way will sound video signal, and pictures and scroll subtitles, multimedia information through network transmission to the displayed Terminal, real-time to released visits information, and rehabilitation center image advertising, and medical common sense, and experts introduced, health life, information. and can at any time spots pictures, news, emergency notification, content, main distribution in Center of Hall, hospital handle district, Elevator Hall, public. Systems Management Server security management on the medical floor room, connect to the streaming media over a network control terminals, control terminals and display devices such as LCD TVs, LED screens and other equipment connected, the output information, system support

MPEG1/2/4,WMV,AVI and other video format, supports image formats such as JPG,PNG,GIF, support DTS/AC3, MP3 MPEG1/MPEG2 MP3,WMA audio format support slide presentations ( PPT). Hours second time Kok's public

security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy

2.2.3 调谐器的维修

调谐器处于整机前端,且维修较难,故在排除调谐器故障前,必须确定其他部位是正常时才可动手。判断的方法,一是鉴别调谐器IF端子至图像中放以后是否正常;二是试做选台操作,测调谐器各端子电压。若不正常,则属调谐器接口或电源故障。

(1) V/U段都收不到台,故障在调谐器U,V段公共通道,如V段混频器可能损坏; (2) V段或U段都收不到台,则为V段或U段本振停振,高放损坏,通道有断路或短路故障;

(3) V段低端有台,高端无台,则为高段切换二极管及电路故障;

(4) 收台不稳,则除调谐电压通路、AFT电压通路故障外,可能是有关调谐元器件性能变坏。

2.3 伴音电路的故障检修

2.3.1 伴音电路的作用

伴音电路的功能是对伴音信号进行解调和放大。它先将6.5MHz调频的第二伴音中频信号放大,用解调器进行调频解调,解出音频信号,再经音频放大器放大后去推动扬声器发声。

2.3.2 伴音电路常见故障

伴音电路常见的故障是,在收视状态下图像正常而无伴音或伴音较小,伴音噪声大,声音失真,有交流声。

2.3.3 伴音电路的维修

2.3.3.1 无声

这里是指图像正常而无声音的情况。造成这种现象的故障原因有:

(1)电源故障。伴音通道中既有小信号电路,也有功率放大电路,由多组电源供电,缺少某一供电电源时将会无声,这时不用测量有关电压,就可直接判断。

从产生第二伴音中频信号到扬声器的通道中,其串联员器件断路或并联短路,都将中断信号传递造成无声。

(2)有关选频回路严重失谐,如6.5MHz滤波器,鉴频调谐回路失调等,将无法检出声音信号。

(3)电子衰减直流控制电压失常,出现故障的部位可能是直流音量控制电位器损坏,或因静噪消音电路故障,而使电路处于静噪或消音状态,也可能是微处理器控制电路输出的音量控制电压通路故障。

对无声的检查排除方法最宜用从输出电路逐级向前输入信号来进行,有经验的也可用螺丝刀逐级碰触各级输入端,根据扬声器发出的噪声大小来判断故障位置,进行相应处理。 2.3.3.2 音小

凡造成上述无声现象的故障部位的都可以造成声音小的故障,可采用处理无声故障的方法检查声音小的问题。在中频变压电路中,图像中频特性曲线上的

31.5MHz伴音中频点若压缩过低,也会造成音小,这时可调节中频耦合变压器或吸收回路的线圈。

2.3.3.3 声音失真

声音失真的原因一般有:一是鉴频电路故障,主要是鉴频线圈失谐;二是音频放大电路有故障,特别是分立元器件的功放电路,部分元器件损坏,工作点漂移及反馈电路中断等造成的非线形失真,都会造成声音失真。

2.4 行、场扫描电路的故障检修

2.4.1 行、场扫描电路的作用

场、行扫描电路功能是向场、行偏转线圈提供线形良好、幅度足够的场频和行频锯齿波电流,使电子束发生有规律的偏转,以保证在彩色显像管屏幕上形成宽高

比正确而且线形良好的光the neighbouring frequency transmission planning, the system can accommodate more than more than 80 TV channels, 2 reverse channels. Taking into account the needs of e-commerce in the future,

this system increase in backhaul bandwidth, take up to 4 channels. Wired TV distribution statistics following table: Wired TV information points distribution schedule-medical floor, rehabilitation floor, 1th, floor, 2nd, floor serial number a layer two layer three layer four layer five layer underground a layer underground two layer total medical floor 53 54 52 71 54 7 5 296 rehabilitation floor 7 5 5 4 4 2 27 2nd, floor 18 18 10 46 1th, floor-East floor 16 16 16 3 51 1th, floor-in the floor 21 15 12 5 53 1th, Floor-West floor 20 15 18 3 56 total 529 (3) information guide and the released system system used concentrated control, and unified management of way will sound video signal, and pictures and scroll subtitles, multimedia information through network transmission to the displayed Terminal, real-time to released visits information, and rehabilitation center image advertising, and medical common sense, and experts introduced, health life, information. and can at any time spots pictures, news, emergency notification, content, main distribution in Center of Hall, hospital handle district, Elevator Hall, public. Systems Management Server security management on the medical floor room, connect to the streaming media over a network control terminals, control terminals and display devices such as LCD TVs, LED screens and other equipment connected, the output information, system support

MPEG1/2/4,WMV,AVI and other video format, supports image formats such as

JPG,PNG,GIF, support DTS/AC3, MP3 MPEG1/MPEG2 MP3,WMA audio format support slide presentations ( PPT). Hours second time Kok's public security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy 栅。另外行输出级通过行输出变压器,还产生高压、副高压、低压,为显像管及其他电路提供电源。

2.4.2 行扫描电路的常见故障

行扫描电路是彩色电视机完成水平扫描的电路,此外,它还为显像管提供高压和副高压,还有许多电路需要的电压。如果行电路失常,往往会引起彩电不能正常工作,无图像无光栅,图像变窄,屏幕变黑,行拉伸或相位不对,不同步,行失真等现象。

2.4.3 行扫描电路的维修

(1)屏幕变黑。如果显像管屏幕是黑的(无光栅),但是声音良好,这表明低压供电电路是良好的,那么在进行故障检修时首先应该检测行驱动电路的输入波形。如果此处波形正常,则说明故障可能出现在行驱动行输出电路,高压电路或者显像管供电电路。如果此处波形不正常,则故障可能出现在行振荡器中。

如果同步脉冲不正常,则故障出现在同步分离电路中;如果比较脉冲不正常,而行激励电路输出的信号良好,那么很可能是行输出电路和高压电路出了故障。

(2)图像变窄。图像变窄并且调整相应的部分也不能使之正常,这种故障的原因往往是行激励不足。

(3)行拉伸或相位不对,不同步。当图像扫伸成一条条斜条状态时,说明行不同步,如果图像完全呈分裂的一条条斜花纹,就表明彻底没有同步信号了。从倾斜的方向可以看出有关故障的信息,如果行向右下倾斜,表明振荡器的频率可能偏高

了,或者正好相反;如果图像整个向左或向右偏移,则说明可能是行相位不正确,即行振荡器的振荡频率正确,只是它与同步信号的相位不同。

有时因调整不当也会引起诸如此类的故障,所以在进行检修时应该首先对所有的与行同步相关的调整旋钮进行调整,如果这样做解决不了问题,再去对所有信号的波形、晶体管的电压及与之相连的集成电路的管脚处的信号一一进行检测。应该特别注意送到AFC电路的同步脉冲和比较脉冲是否正常。如果经检测发现这两个信号都没有或信号不正常,则AFC电路就不能正常工作。

(4)行失真,行振荡器及激励电路不良会引起许多形成的行失真故障现象,这种故障发生时,图像在垂直方向上呈不规律的S形,这样的失真一般是由于行扫描电路中某元器件变质所致,不是完全损坏造成的,最常见的原因是电容损坏,特别是对AFC电路送行振荡器的同步控制电压进行滤波的电容很可能损坏。

2.4.4 行输出电路的常见故障

行输出电路不良所引起的许多故障现象也可由其他电路中的故障引起,屏幕发黑或亮度不足就是两个常见的故障。

2.4.5 行输出电路的维修

(1)黑屏故障的一般检测方法。在屏幕完全变黑的情况下,应该先测量一下显像管各极电压。如果各极的电压都正常,那么屏幕变黑就可能是因显像管损坏。如果显像管高压和辅助电压都没有或不正常,那么就说明相关电路出了故障;如果这两个电压都没有,而行激励信号却是良好的,则可能是行激励电路和行输出管或与其相连的某部分出了故障。如果没有高压,则应该检测一下聚焦电流或电压。

(2)亮度不足的一般检测方法。如果显像管阳极高压幅度不足,图像亮度就不够,行幅增大严重者会导致完全没有图像,这时应检查阳极高压线是否断线或内部高压线圈和整流二极管是否损坏,若都完好,则应检查变压器所有次级负载电路及行输出电路。聚焦极高压不足,会使聚焦效果变差,导致整个图像模糊不清。如果

显像管阳极高压正常,则此故障可能是聚焦电位器或内部线圈损坏,若聚焦电压正常,则可能是显像管聚焦插针接触不良,应更换管座。

the neighbouring frequency transmission planning, the system can accommodate more than more than 80 TV channels, 2 reverse channels. Taking into account the needs of e-commerce in the future, this system increase in backhaul bandwidth, take up to 4 channels. Wired TV distribution statistics following table: Wired TV information points distribution schedule-medical floor, rehabilitation floor, 1th, floor, 2nd, floor serial number a layer two layer three layer four layer five layer underground a layer underground two layer total medical floor 53 54 52 71 54 7 5 296 rehabilitation floor 7 5 5 4 4 2 27 2nd, floor 18 18 10 46 1th, floor-East floor 16 16 16 3 51 1th, floor-in the floor 21 15 12 5 53 1th, Floor-West floor 20 15 18 3 56 total 529 (3) information guide and the released system system used concentrated control, and unified management of way will sound video signal, and pictures and scroll subtitles, multimedia information through network transmission to the displayed Terminal, real-time to released visits information, and rehabilitation center image advertising, and medical common sense, and experts introduced, health life, information. and can at any time spots pictures, news, emergency notification, content, main distribution in Center of Hall, hospital handle district, Elevator Hall, public. Systems Management Server security management on the medical floor room, connect to the streaming media over a network control terminals, control terminals and display devices such as LCD TVs, LED screens and other

equipment connected, the output information, system support

MPEG1/2/4,WMV,AVI and other video format, supports image formats such as JPG,PNG,GIF, support DTS/AC3, MP3 MPEG1/MPEG2 MP3,WMA audio format support slide presentations ( PPT). Hours second time Kok's public security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy

2.4.6 场扫描电路的常见故障

场扫描电路是为场偏转线圈提供锯齿波电流的电路。场扫描电路的故障主要表现为图像垂直方向不良,具体情况包含有图像有滚动现象,图像高度不足,图像不稳、分裂等。 2.4.7 场扫描电路的维修

(1)图像滚动现象。若图像有滚动现象,而调整场同步电位器只能暂时稳定图像,这表明行同步电路正常,因为只有垂直方向不稳定。从症状来看属同步分离电路或场扫描信号形成电路有故障,而场振荡电路是正常的。

在检测场同步脉冲和行同步脉冲的波形时,可以把示波器的扫描频率分别置于25Hz和7812Hz,如果示波器具有选测电视行和选测电视功能,在检测场信号时开关将置于选测电视场位置,在选测行信号时将开关置于选测电视行位置,这样就可以在示波器上观测到稳定的信号波形。

如果同步分离电路不良,不能对所需要的信号进行有效的分离,有视频信号混入同步信号中,就会引起图像同步不良,检测同步分离电路是否有故障,可以通过信号的检测来判断,同步分离前是视频信号,同步分离后应当没有视频信号的成分。如果同步信号中混有视频或杂波信号,则表明同步分离电路有故障。

(2)图像高度不足。图像高度不足是指图像在垂直方向有压缩的现象,遇到这

种故障时应先调整一下场幅微调电位器。如果场幅微调电位器必须旋至极端位置或将近极端位置时图像高度才正确,这表明场驱动电路中有故障;如果调整场幅电位

器时图像有反应,但无论怎么调都不能使图像高度完全正常,这时应当检查与场幅相关的电容,看有关电容是否有漏电的情况,电位器有无损坏,以及晶体管有无击穿的情况,同时,应检查从场扫描电路送到场偏转线圈的脉冲波形是否正常,场输出级供电电源是否正常,电源电压不足也会影响场扫描电路的正常工作。

(3)图像不稳,上下抖动。图像不稳的主要表现是图像上下滚动,整幅图像抖动。这种情况一般表明场频不稳定或场频偏离50Hz,应检查与场振荡电路有关的电容、晶体管或电位器等,集成电路本身损坏的情况也是不能忽视的,故应检查集成电路所有管脚的直流工作电压,看有无偏离标准值,这是判断集成电路是否损坏的依据。

(4)场失真。场失真有多种表现形式,其中包括线形失真。线形失真在多数情况下是由于偏转线圈及其相关的部分出现故障引起的,有时扫描集成电路不良也会引起这种故障。如果场失真不严重,采用电视信号发生器产生的十字阴影图信号对图像进行线形检测比较方便,如果要迅速地判断图像的线形是否良好,可以调整一下场同步控制钮,使图像慢慢地滚动起来,这样容易发觉图像的上部、中部和下部在垂直方向上是否一致,有无压缩和扩展现象。

有时场幅电位器调整不当也会影响图像的线性而造成失真,这是因为场扫描电路中各组成部件和调整控制元器件之间是互相有牵连的。遇到这种情况要检查场幅电位器调整得是否恰当,可以试调整一下,配合失真的情况再进一步调整。

如果调整各个电位器都不能解决问题,表明有故障的元器件存在。要寻找故障元器件,必须对电路中的信号波形和直流电压进行逐级检查。如果场扫描的锯齿波信号失真,必然影响图像的线形。如果场输出级送给场偏转线圈的信号波形是良好的,但图像仍然有失真现象,这种情况表明场偏转线圈或相关的部分有故障。

2.5 开关电源的故障检修

2.5.1 开关电源的作用与常见故障

它的功能是向彩色电视各电路提供各种工作电压

电源电路发生故障时往往会使彩电完全不能工作,主要表现为开机后无任何反应,既无the neighbouring frequency transmission planning, the system can accommodate more than more than 80 TV channels, 2 reverse channels. Taking into account the needs of e-commerce in the future, this system increase in backhaul bandwidth, take up to 4 channels. Wired TV distribution statistics following table: Wired TV information points distribution schedule-medical floor, rehabilitation floor, 1th, floor,

2nd, floor serial number a layer two layer three layer four layer five layer underground a layer underground two layer total medical floor 53 54 52 71 54 7 5 296 rehabilitation floor 7 5 5 4 4 2 27 2nd, floor 18 18 10 46 1th, floor-East floor 16 16 16 3 51 1th, floor-in the floor 21 15 12 5 53 1th, Floor-West floor 20 15 18 3 56 total 529 (3) information guide and the released system system used concentrated control, and unified management of way will sound video signal, and pictures and scroll subtitles, multimedia information through network transmission to the displayed Terminal, real-time to released visits information, and rehabilitation center image advertising, and medical common sense, and experts introduced, health life, information. and can at any time spots pictures, news, emergency notification, content, main distribution in Center of Hall, hospital handle district, Elevator Hall, public. Systems Management Server security management on the medical floor room, connect to the streaming media over a network control terminals, control terminals and display devices such as LCD TVs, LED screens and other

equipment connected, the output information, system support

MPEG1/2/4,WMV,AVI and other video format, supports image formats such as JPG,PNG,GIF, support DTS/AC3, MP3 MPEG1/MPEG2 MP3,WMA audio format support slide presentations ( PPT). Hours second time Kok's public security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy 光栅也无伴音。

2.5.2 开关电源的维修

开关电源的检修方法与其他部分基本相同。遇到故障机时,首先进行症状观察,然后根据电路结构进行分析、推测;接下来是进行检测,根据检测的结果再进一步分析、推测。通过检测、分析和推测找到可疑部件,然后再进行元器件的检修和代换。对于本身薄弱的机器,可以首先检测或代换易于损坏的元器件,如开关管或相关元器件。

2.6 显像管电路的检修

2.6.1 显像管电路的作用与常见故障

显像管电路功能是将R、G、B三基色信号放大后加至显像管3个阴板,控制显像管3个电子枪电子束的强弱。

显像管电路是电视主体电路与显像管之间的接口电路。电视的主体电路如有故障,使送到显像管电路的信号失常,就会使图像失常甚至完全没有图像。如果显像管电路中的某些元器件损坏,会使加给显像管电路的某些信号或电压不正常。显像管电路板污物过多,可能引起电路之间漏电,在加速极和聚集电极电路中常会出现这种情况,这是因为加速极和聚集极的直流电压比较高,再则显像管内部损坏或极间有短路或碰极的情况,都会造成图像失真。 2.6.3 显像管电路的维修

(1)色偏。在显像管电路中,主要的元器件是视放晶体管和它的偏置元器件,任何一个视放晶体管不良都会引起色偏。如果屏幕上表现为基本全红,则红视放输出晶体管出现击穿短路的故障,如果表现为缺红故障,则红输出晶体管烧断,完全无电视,同理,如果蓝输出或绿输出视放晶体管出现与上述类似的故障,则会出现全绿、全蓝或缺绿、缺蓝的故障。如果视放输出级的直流电源有故障,会使显像管3个阳极的电压几乎降低至零,则3条电子束流都会达到最大值,图像表现为全白光栅,束流过大,有些电视会自动进入保护状态,并转为无光栅、无图像。检测直流电压即可判明故障,末级视放电源的正常电压为180,200V。如果加速级电压有故障,则会出现图像暗且不清晰;如果此电压偏高,会出现回扫线;如果聚焦极电压失落或偏低,会出现聚焦现象,使图像模糊不清。在显像管座内部有放电装置,如果因其中有污物或受潮而造成漏电,会影响相关电极的电压,也自然会出现各种故障。阳极高压电路出现故障或高压嘴接触不良,会产生无图、无光栅等现象。如果高压失落,会出现无光栅现象;如果高压过高,会出现图象缩小现象,并会引起自动保护;如果高压偏低,会出现图象扩大并散焦的现象。

(2)会聚不良。彩色电视机在接收黑白方格信号时,红、绿、蓝三条线束不重合,分离成彩色条格子或彩色交叉线,称做会聚不良。荧光屏中心附近会聚不良为静会聚不良,而屏幕四周区域会聚不良成为动会聚不良。

动会聚不良主要是由偏转线圈位置变化引起的。排除方法是:在确认静会聚良好的情况下,将偏转线圈的位置固定后,若发现蓝光束比红光束偏得更大,就将偏转线圈向右倾斜;若发现红光束偏得更大,就将偏转线圈向左倾斜一些。

静会聚不良主要是由于运输不当或人为乱调使偏转线圈和会聚磁环组件的位置发生变化而产生的。排除方法是重新将偏转线圈的位置调正并紧固,然后分别小心反复调整四极磁环两磁片或六极磁环两磁片的夹角和旋转位置,使红、绿、蓝3条电子束重合。另外,还需微调相邻的色纯磁片与之配合。

当静会聚和动会聚不良经调整不能消除时,则应怀疑偏转线圈内部有局部短路

现象,会聚磁环组件失效或显像管内部荫罩板变形,这只有更换有关零件或显像管才能消除。 (3)色纯度不良。当色纯度不良时,应首先检查自动消磁线圈和热敏电阻是否开路,使开机时自动消磁电路无法工作。当荧光屏受到强磁场的影响,使屏内金属网罩局部磁化而引起色纯度不良时,其剩磁较强,用自动消磁电路已无法使其消磁,需用机外消磁的方法进行处the neighbouring frequency transmission planning, the system can accommodate more than more than 80 TV channels, 2 reverse channels. Taking into account the needs of e-commerce in the future, this system increase in backhaul bandwidth, take up to 4 channels. Wired TV distribution statistics following table: Wired TV information points distribution schedule-medical floor, rehabilitation floor, 1th, floor, 2nd, floor serial number a layer two layer three

layer four layer five layer underground a layer underground two layer total medical floor 53 54 52 71 54 7 5 296 rehabilitation floor 7 5 5 4 4 2 27 2nd, floor 18 18 10 46 1th, floor-East floor 16 16 16 3 51 1th, floor-in the floor 21 15 12 5 53 1th, Floor-West floor 20 15 18 3 56

total 529 (3) information guide and the released system system used concentrated control, and unified management of way will sound video signal, and pictures and scroll subtitles, multimedia information

through network transmission to the displayed Terminal, real-time to released visits information, and rehabilitation center image advertising, and medical common sense, and experts introduced, health life, information. and can at any time spots pictures, news, emergency notification, content, main distribution in Center of Hall, hospital

handle district, Elevator Hall, public. Systems Management Server security management on the medical floor room, connect to the streaming media over a network control terminals, control terminals and display devices such as LCD TVs, LED screens and other equipment connected, the output information, system support MPEG1/2/4,WMV,AVI and other video format, supports image formats such as JPG,PNG,GIF, support DTS/AC3, MP3 MPEG1/MPEG2 MP3,WMA audio format support slide presentations ( PPT). Hours second time Kok's public security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy

理;运输不当造成偏转线圈松脱、移位,或色纯度调节磁铁损坏而引起色纯度

不良时,应重新紧固偏转线圈并重新调节色纯度磁铁;若属显像管内栅网、荫罩板、电子枪等移位、变形而引起的色纯度不良,只有更换彩色显像管才能解决。

结束语

通过对电视机原理的详细了解和对电视机常见故障的系统分析与排除,不仅使我对电视机有了的全面了解,而且使我对微电子技术、信号处理和智能控制等新技术的具体应用有了部分了解。在此,我特别感谢我的指导老师王老师的耐心和全面的指导。

the neighbouring frequency transmission planning, the system can accommodate more than more than 80 TV channels, 2 reverse channels. Taking into account the needs of e-commerce in the future, this system increase in backhaul bandwidth, take up to 4 channels. Wired TV distribution statistics following table: Wired TV information points distribution schedule-medical floor, rehabilitation floor, 1th, floor,

2nd, floor serial number a layer two layer three layer four layer five layer underground a layer underground two layer total medical floor 53 54 52 71 54 7 5 296 rehabilitation floor 7 5 5 4 4 2 27 2nd, floor 18 18 10 46 1th, floor-East floor 16 16 16 3 51 1th, floor-in the floor 21 15 12 5 53 1th, Floor-West floor 20 15 18 3 56 total 529 (3) information guide and the released system system used concentrated control, and unified management of way will sound video signal, and pictures and scroll subtitles, multimedia information through network transmission to the displayed Terminal, real-time to released visits information, and rehabilitation center image advertising, and medical common sense, and experts introduced, health life, information. and can at any time spots pictures, news, emergency notification, content, main distribution in Center of Hall, hospital handle district, Elevator Hall, public. Systems Management Server security management on the medical floor room, connect to the streaming media over a network control terminals, control terminals and display devices such as LCD TVs, LED screens and other equipment connected, the output information, system support

MPEG1/2/4,WMV,AVI and other video format, supports image formats such as JPG,PNG,GIF, support DTS/AC3, MP3 MPEG1/MPEG2 MP3,WMA audio format support slide presentations ( PPT). Hours second time Kok's public security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy

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