只要背光板电路异常，肯定导致液晶屏黑屏的故障

背光板黑屏的检修思路液晶屏背光板故障较多的原因，一是背光板消耗的功率较大：二是逆变电路的功率管散热不良和功率管的功率余量不足。
无论什么液晶屏．只要背光板电路异常，肯定导致液晶屏黑屏的故障　修：查N100同步分离电路未见异常，查N100(17脚PH1.LF)外围元件，发现C159(4700P/50v)电容有20K的漏电阻值。更换C159后故障修复。 故障现象：有时开机行场不同步，有时正常，正常时可以收看一两个小时。客户讲夏天故障比较频繁？输入的液晶屏，背光板往往不独立，常与开关电源合在一块电路板上。配置电源适配器的液晶屏，背光板往往是独立的，非常方便检测和更换。 此机采用三洋单片机LA7688，小信号处理全在内部。试验AV输入功能，VCD画面正常，分析故障还在LA7688中放相关电路。翻阅相关资料，中频AGC、高放延迟AGC分别由LA7688的46脚、52脚及2脚内外部电路共同完成。而46脚为中放AGC滤波，外接电容C162对内部中频放大电路影响重大，用0.47uf/50V电容代换后长时间试机图像稳定。
此故障初看不大，但是所走弯路不少，所费功夫不短。而两处信号不同故障现象稍有不同，也掩盖了故障本质






http://www.huihui.cn/share/10268086
http://www.huihui.cn/share/10268067
http://www.huihui.cn/share/10268040
http://www.huihui.cn/share/10267996
http://www.huihui.cn/share/10267978
http://www.huihui.cn/share/10267959
http://www.huihui.cn/share/10267924
http://www.huihui.cn/share/10267893
http://www.huihui.cn/share/10267875
http://www.huihui.cn/share/10267857
http://www.huihui.cn/share/10267811
http://www.huihui.cn/share/10267773
http://www.huihui.cn/share/10267604
http://www.huihui.cn/share/10267586
http://www.huihui.cn/share/10267532
http://www.huihui.cn/share/10267464
http://www.huihui.cn/share/10267441
http://www.huihui.cn/share/10267417
http://www.huihui.cn/share/10267382
http://www.huihui.cn/share/10267348
http://www.huihui.cn/share/10267288
http://www.huihui.cn/share/10267248
http://www.huihui.cn/share/10267220
http://www.huihui.cn/share/10267119
http://www.huihui.cn/share/10267067
http://www.huihui.cn/share/10267017
http://www.huihui.cn/share/10266971
http://www.huihui.cn/share/10266936
http://www.huihui.cn/share/10266907
http://www.huihui.cn/share/10266880
http://www.huihui.cn/share/10266833
http://www.huihui.cn/share/10266726
http://www.huihui.cn/share/10266677
http://www.huihui.cn/share/10266594
http://www.huihui.cn/share/10266563
http://www.huihui.cn/share/10266217
http://www.huihui.cn/share/10266475
http://www.huihui.cn/share/10266194
http://www.huihui.cn/share/10266130
http://www.huihui.cn/share/10266099
http://www.huihui.cn/share/10265905
http://www.huihui.cn/share/10265891
http://www.huihui.cn/share/10265879
http://www.huihui.cn/share/10265869
http://www.huihui.cn/share/10265859
http://www.huihui.cn/share/10265830
http://www.huihui.cn/share/10265815
http://www.huihui.cn/share/10265795
http://www.huihui.cn/share/10265774
http://www.huihui.cn/share/10265753
http://www.huihui.cn/share/10265723
http://www.huihui.cn/share/10265702
http://www.huihui.cn/share/10265686
http://www.huihui.cn/share/10265675
http://www.huihui.cn/share/10265659
http://www.huihui.cn/share/10265646
http://www.huihui.cn/share/10265627
http://www.huihui.cn/share/10265606
http://www.huihui.cn/share/10265583
http://www.huihui.cn/share/10265552
http://www.huihui.cn/share/10265539
http://www.huihui.cn/share/10265525
http://www.huihui.cn/share/10265505
http://www.huihui.cn/share/10265482
http://www.huihui.cn/share/10265455
http://www.huihui.cn/share/10265437
http://www.huihui.cn/share/10265417
http://www.huihui.cn/share/10265392
http://www.huihui.cn/share/10265373
http://www.huihui.cn/share/10265351
http://www.huihui.cn/share/10265331
http://www.huihui.cn/share/10265303
http://www.huihui.cn/share/10265267
http://www.huihui.cn/share/10265237
http://www.huihui.cn/share/10265204
http://www.huihui.cn/share/10265179
http://www.huihui.cn/share/10265128
http://www.huihui.cn/share/10265087
http://www.huihui.cn/share/10265050
http://www.huihui.cn/share/10265013
http://www.huihui.cn/share/10264984
http://www.huihui.cn/share/10264953
http://www.huihui.cn/share/10264918
http://www.huihui.cn/share/10264895
http://www.huihui.cn/share/10264848
http://www.huihui.cn/share/10264814
http://www.huihui.cn/share/10264791
http://www.huihui.cn/share/10264775
http://www.huihui.cn/share/10264760
http://www.huihui.cn/share/10264722
http://www.huihui.cn/share/10264697
http://www.huihui.cn/share/10264662
http://www.huihui.cn/share/10264638
http://www.huihui.cn/share/10264615
http://www.huihui.cn/share/10264591
http://www.huihui.cn/share/10264559
http://www.huihui.cn/share/10264532
http://www.huihui.cn/share/10264498
http://www.huihui.cn/share/10264476
http://www.huihui.cn/share/10264442
http://www.huihui.cn/share/10264423
http://www.huihui.cn/share/10264388
http://www.huihui.cn/share/10264317
http://www.huihui.cn/share/10264291
http://www.huihui.cn/share/10264267
http://www.huihui.cn/share/10264244
http://www.huihui.cn/share/10264201
http://www.huihui.cn/share/10264144
http://www.huihui.cn/share/10264119
http://www.huihui.cn/share/10264061
http://www.huihui.cn/share/10264037
http://www.huihui.cn/share/10263990
http://www.huihui.cn/share/10263968
http://www.huihui.cn/share/10263935
http://www.huihui.cn/share/10263955
http://www.huihui.cn/share/10263919
http://www.huihui.cn/share/10263896
http://www.huihui.cn/share/10263871
http://www.huihui.cn/share/10263816
http://www.huihui.cn/share/10263842
http://www.huihui.cn/share/10263803
http://www.huihui.cn/share/10263781
http://www.huihui.cn/share/10263761
http://www.huihui.cn/share/10263746
http://www.huihui.cn/share/10263724
http://www.huihui.cn/share/10263694
http://www.huihui.cn/share/10263672
http://www.huihui.cn/share/10263647
http://www.huihui.cn/share/10263617
http://www.huihui.cn/share/10263599
http://www.huihui.cn/share/10263586
http://www.huihui.cn/share/10263564
http://www.huihui.cn/share/10263535
http://www.huihui.cn/share/10263519
http://www.huihui.cn/share/10263505
http://www.huihui.cn/share/10263487
http://www.huihui.cn/share/10263471
http://www.huihui.cn/share/10263451
http://www.huihui.cn/share/10263435
http://www.huihui.cn/share/10263420
http://www.huihui.cn/share/10263403
http://www.huihui.cn/share/10263385
http://www.huihui.cn/share/10263360
http://www.huihui.cn/share/10263324
http://www.huihui.cn/share/10263298
http://www.huihui.cn/share/10263271
http://www.huihui.cn/share/10263230
http://www.huihui.cn/share/10263202
http://www.huihui.cn/share/10263175
http://www.huihui.cn/share/10263150
http://www.huihui.cn/share/10263075
http://www.huihui.cn/share/10263095
http://www.huihui.cn/share/10263042
http://www.huihui.cn/share/10263024
http://www.huihui.cn/share/10262997