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[例1]故障现象 下半部图像正常,上半部图像压缩,且中间有很窄的一条水平亮带。除此之外,伴音、亮度、色度、对比度皆正常。 分析与检修 初步判断为场线性不良。仔细检查场辅出厚膜集成块7400(TDA3651AQ)周围的电路元件,特别是场线性调整电路元件3401、3408、3409、3421及2407等都正常。调场线性电位器3401,上部场幅能微微拉开,后在电位器3401(阻值为82kΩ)上串接一阻值为200kΩ的电阻,再调3401时水平亮带消失,场幅能拉开,但场线性仍然不良,图像有上卷边。看来问题不在这里。检查行、场振荡及同步集成块7875即(TDA2577A)的①、②、③脚外接电路元件2410、3810、3813无问题,此时,不
[Example 1] Symptom The image in the lower half is normal, the image in the upper half is compressed, and there is a narrow horizontal bright band in the middle. In addition, sound, brightness, color, contrast are normal. Analysis and maintenance of the initial judge as a linear field of bad. Careful inspection of the field auxiliary thick film manifold 7400 (TDA3651AQ) around the circuit components, in particular the field linearity adjustment circuit components 3401,3408,3409,3421 and 2407 are normal. Field adjustable linear potentiometer 3401, the upper field amplitude can be slightly opened, after the potentiometer 3401 (resistance value of 82kΩ) connected in series with a resistance of 200kΩ resistor, the level of brightness disappear when the redistribution of 3401, the field can pull On, but the field linearity is still poor, the image has curled edge. It seems the problem is not here. Check the line, field oscillation and synchronous block 7875 (TDA2577A) ①, ②, ③ pin external circuit components 2410,3810,3813 no problem, this time, do not