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故障现象:开机红光栅且越来越亮,几秒后自动停机。故障检修:从现象判断,问题应在视频通道中,而且重点在红色视放电路上。首先从信号输入端开始静态检查,经测试14根信号输入线连接无误。继而重点检查由集成电路 LM1207组成的视频信号放大器以及由分立元件组成的视频放大输出电路。根据红、绿、蓝三个通道电路对称的原理,采用静态测试关键点对地电阻值的方法。首先对视频输出电路进行测试,结果无发现明显异常之处,尔后检测集成电路 LM1207各有关脚对地电阻,发现第(27)脚(红色截止调节)对地
Symptoms: boot red grating and more and more bright, automatically shut down after a few seconds. Troubleshooting: judging from the phenomenon, the problem should be in the video channel, but also focus on the red as the release circuit. First of all static input signal from the start, the test 14 signal input line connection is correct. Then focus on inspection by the integrated circuit LM1207 composed of video signal amplifier and composed of discrete components of the video amplifier output circuit. According to the red, green, blue three-channel circuit symmetry principle, the static test of the key point to ground resistance value method. First of all, the video output circuit to test the results found no significant anomalies, and then detect the integrated circuit LM1207 foot-to-ground resistance, found that (27) (red cut-off regulation) on the ground