电视机有图像无声音课堂教学1

电视机有图像无声音课堂教学1 课堂教学 教师:上课! 学生:老师好 教师:同学们好,请坐 这次课的课名称:电视机有图像，无声音故障的检修。 教学目标:知识目标:了解电视机有图像，无声音故障出现故障的原因 能力目标:掌握对电视机出现的有图像，无声音故障的维修方法 素质目标:通过对电视机故障的检修，提高学生的动手能力和学习兴趣。 教学重点:电视机有图像，无声音故障的分析 教学难点:电视机有图像，无声音故障的检修 教师:说到维修电视机,那么我想问下同学们知道在生活中电视机出现的故障想会有哪些呢, 学生:无图像，黑屏，图像偏色，有雪花点，收不到节目。。。 教师:还有吗, 学生:无字幕，无声音。。。 教师:嗯，很好。现在同学们都看到我们的桌子上有四台有故障的电视机，下面同学们分成四个小组选好自己要修的电视机坐好。 教师:现在桂林某维修部有一批有故障的电视机，需要对四台康佳P21SA387型号的电视机进行维修。要求电子班接到此任务后，在一天内完成故障的维修，并交有关人员验收。 工作任务联系单 维修地点 桂林某维修部 维修项目 康佳P21SA387电视机的维修 数量 4台 负责人 黄某 2013年12月派工部门 桂林某维修部 派工时间 10日 联系电话 2693479 负责人 李某 维修单位或2013年12月机电系 承接单位 部门 10日 联系电话 2691587 年 月 维修人员 完工时间 日 验收意见 验收人 教师:现在同学们都明白自己的工作任务了吗, 学生:明白了～ 教师:嗯，很好。那么，接下来，每个小组的同学派代表拿好需要的电视机图纸 和维修工具，并查找电视机出现的故障，在小组里讨论出现的故障的部分 会在哪个电路里。 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 ( ). Hours second time Kok's public security system ... Information for safe, reliable, and mature application of equipment and advanced technology to the enemy (学生拿工具和图纸，开电视，查看电视故障，分析故障可能出现的部分。)(5 分钟) 教师:同学们，查出电视机的故障了吗, 学生:查出了。 教师:电视机的故障是什么呢,第一组。。。。 学生:有图像没有声音。(学生分组回答) 教师:嗯，很好。同学们都查正确了。那么有图像无声音故障可能出现在电路中 的哪个部分呢, 学生: TV/AV切换电路，第二伴音中频处理电路，扬声器和音频功率放大电路 (学生一起分开回答) 教师:还有吗, 学生:没有了。 教师:很好，我们同学回答得很好啊。电视有图像无声音故障可能出现的部分在 第二伴音中频处理电路，鉴频电路，TV/AV切换电路了，音频放大电路， 扬声器这几个部分。 下面同学们在小组里讨论下出现这个故障在这几个部分应该怎样检修。然 后按自己的方法检修电视机。做好的可以举手告诉老师。修好后，每个小 组派代表讲解本小组检修的步骤。 (学生开始开始关机拔电源，拆电视，放电，检修电视，然后把坏的部分修好。 举手示意老师。写完的完成题目。) (教师四处走动，并查看学生工作情况。)(十分钟) 教师:同学们都做好了，很好,并且都能把故障修好了。下面，请每个小组的同 学把本组修好的电视机打开，让大家看看自己维修的成果。 学生:好。 (学生分组打开电视机) 教师:很好啊。大家都把自己的电视机修好了。现在请各小组派一个同学说一下 自己维修的步骤。 (学生分组大声的回答) 学生1:第一步，测量18V电源电压正常。第二步，测N101一脚电压正常。故 障可能出自静躁电路或N181本身。第三步，测量静躁电路元件发现V185 的c-e极击穿短路，更换同型号三极管后，伴音恢复正常。 学生2:用直观检查法检查电路板和扬声器等，发现扬声器的连接线断开，焊接 好后开机恢复正常。 学生3:用干扰法检测电路，第一步，断开N103的五十三脚，用金属导体干扰 R250或R260右端，听喇叭有“咯咯”声。第二步，查N103的十脚，电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 压正常。第三步，检查电容，电容虚焊，更换电容后恢复正常。 学生4,:测量N18125V电源电压，电压为零，检测电源电路，发现三极管被击 穿，更换三极管，伴音恢复正常。 教师:都说得很好啊。在电视机有图像无声音故障的维修的步骤。首先是检查扬 声器及其插座的连线。然后检查伴音功放和静音电路。接着，检查伴音信 号前置处理电路。最后，检查伴音中频电路和制式切换。 检查出故障后，我们直接把虚焊，烧坏，或短路的元器件修好就可以了。 在这次的维修中，做得比较好的小组是 组，第 组的焊接有待加强。 第 组的效率有待加强，第 组的同组间的配合程度有待提高。 竟然讲到电视机的维修,那么我们来了解下电视机信号处理过程。 首先天线连接的电视信号通过高频调谐器选频放大,变成38MHZ的中频图 像信号,再通过中放电路后送至同步检波器进行同步检波分成两路，一路 经过陷波器后分离出图像信号，最后在显像管输出图像;另一路经过带通 滤波器变成伴音信号，进入伴音电路后推动喇叭发出声音。 下面我们看到的是我们修的这台康佳P21SA387电视机的电路板， 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 在我们的电视机中的序号一到四是我们的伴音电路部分。?:音频处理电 路?:高频调谐器 ?:TV/AV切换电路?:小信号处理电路。 了解了电视信号的处理，下面我们就学习下伴音电路。 一、伴音电路分析 1.伴音电路的组成与作用 电视信号通过高频头变频经过中放、检波、视放后，输出视频图像信号和6.5MHz第二伴音中频信号输入伴音电路，经过6.5MHz的带通滤波器滤除视频信号，剩下的第二伴音中频信号放大后经鉴频器鉴频后输出音频信号，经音频功率放大后推动扬声器发出声音。外围AV音频输入在鉴频后。 2.实际电路分析 伴音电路由LA76810(IC201)内的伴音中频处理电路和音频放大集成电路LA4225(IC601) 组成。 在实际电路中，第二伴音信号从IC201一脚输出，从IC601的一脚输入。在经过伴音电路的处理后在四脚通过扬声器输出。二脚和三脚接地，五脚接24V电源。 看到了电视机电路，我们对比下实际电路，IC201在实际电路中是对应的是哪个模块,我请一个同学回答。 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 (学生纷纷举手) 学生1:IC201对应的是小信号处理电路序号四。 教师:回答正确啊。请坐。那么IC601对应的是哪个电路呢, 学生2:IC601对应的是伴音电路序号一。 教师:好，请坐。我们同学都很厉害都回答正确了啊。那么下面我们学习电视机有图像无声音故障的检修。 二、有图像，无伴音电视检修 打开电视机后屏幕上图像正常，但听不到伴音，将音量调至最大，仍听不到伴音。图像正常，说明公共通道正常;故障只在伴音电路，只要有一处开路或短路，使伴音信号中断，就会造成无伴音的故障。 首先检查扬声器音圈和引线是否正常，若正常，再检测其他电路。 伴音电路主要由电视小信号处理集成电路如LA76810和音频放大集成电路如LA4225组成，首先应判断故障位于哪一部分。可将外部AV信号(如DVD)送入电视机，若伴音正常，说明音频放大级正常，故障位于小信号处理集成电路;反之，若伴音不正常，故障位于音频放大级。 此外，还可以用金属镊子或万用表笔触击小信号处理集成块的音频信号输出端，即LA76810的?脚，若扬声器有“喀喀”声，说明音频放大级正常，故障在小信号处理集成块LA76810及外围元件，通过测量相关各脚的电压，排除外围故障元件后，就是集成块损坏，更换即可;若扬声器没有发出“喀喀”声，说明音频放大级LA4225及外围元件有故障，进一步测量供电电压是否正常、输入输出耦合电容及滤波电容是否损坏，若都正常，说明音频放大集成块损坏，更换即可。 小结: 1、电视机信号处理过程 2、伴音电路的分析 3、电视机有图像，无伴音故障检修 下面布置作业: 一、伴音电路的组成 二、电视机有图像无声音故障维修步骤 好,这次课就上到这里。同学们，下课～ 学生:老师再见～ 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