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故障现象:无光无声,机内有“吱吱”声。分析与检修:根据故障现象分析,怀疑故障出在电源电路或行扫描电路。卸开机壳,检查发现行偏转线圈限流电阻R_(443)烧焦,检查行偏转线圈及电容C_(442)、C_(447)、C_(448)未见异常;检查行输出管Q_(404)及逆程电容均完好,焊下电阻R_(443),测量其阻值已由正常值360Ω变为300Ω。更换此电阻后,测量电源厚膜块Q801(STR5412)第①脚电压为300V,正常。该脚电压正常,说明整流滤波电路工作正常。测第④脚+B电压为51V,正常值应为112V。该脚电压偏低。估计负载有短路故障,并怀疑行输出变压器T461不良。于是,断开
Symptoms: no light, the machine has “creak” sound. Analysis and Maintenance: According to the analysis of the fault phenomenon, suspected of failure in the power circuit or line scan circuit. Open the case, check the line deflection coil current limiting resistor R_ (443) charred, check the line deflection coil and capacitor C_ (442), C_ (447), C_ (448) no exception; check the line output Q_ 404) and the reverse capacitor are intact, resistance R_ (443) welding, measuring the resistance has changed from the normal value of 360Ω to 300Ω. After replacing this resistor, measure the voltage of the thick film block Q801 (STR5412) ① foot voltage is 300V, normal. The normal voltage pin, indicating rectification filter circuit is working properly. Measure the first four feet + B voltage is 51V, the normal value should be 112V. The foot voltage is low. It is estimated that the load has a short-circuit fault and it is suspected that the output transformer T461 is bad. So, disconnect