三无,有吱吱叫声,无声光。开机测行输出管集电极电压正常,行推动管基极电压高达4.5v,说明扫描块OM8838P工作不正常,测行振荡输出端40脚电压也为4.5V,怀疑扫描块损坏,换新后故障依旧,手摸行管发烫,关机,逐个检查三极管,测行ABL电路中到扫描块OM8838P的50脚间的三极管Q404(2SC1815)软击穿,更换,修复。 |
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