测N501(TDA3654)的(9)脚为27V正常,再测(55)脚为13V,中点电压也正常,N501可认为基本工作正常. 查TDA8362的引脚功能,得知其(42)脚为帧锯齿波形成脚,外接R358和C330,拆下R358测其阻值近10MΩ,明显变值(正常值为3.6MΩ)更换R358后帧幅恢复正常. |
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