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故障现象:“三无”,烧坏保险和开关管。检修:开机检查时,发现电源保险丝烧断,电源开关管Q801击穿。为防止再次烧元件,避免故障扩大,用调压器逐渐升压法来检查故障,即通过调压器让电源电压从110V逐渐升高时,仍不启动。检查启动电路(D821、R800、R806),经过R812、R810加到开关集成电路IC801(TEA2261)的(16)、(15)脚上的启动工作电路均正常;又检查正反馈电路也正常。当电压升到210V时,就听到“啪”的一声,保险丝熔断。停电测量,新换上的开关管Q801(BUV488)被击穿。仔细检查IC801的(15)、(14)脚对地电阻,发现偏低,正向测6kΩ,反向测5kΩ,且这两种对地电阻相等,测(15)、(14)脚之间电阻为零。
Symptoms: “three no”, burn insurance and switch. Maintenance: boot check, found that the fuse fuse, power switch Q801 breakdown. To prevent the component from burning up again, to prevent the fault from expanding, check the fault with the step-up regulator method, which is not started when the power supply voltage is gradually increased from 110V by the regulator. Check the starting circuit (D821, R800, R806), after R812, R810 added to the switch IC801 (TEA2261) (16), (15) feet on the start of the normal working circuit; Also check the positive feedback circuit is normal. When the voltage rose to 210V, I heard “snap” sound, the fuse blown. Power outage measurement, the new switch Q801 (BUV488) was breakdown. Carefully check IC801’s (15), (14) feet on the ground resistance, found low, the positive measured 6kΩ, reverse measured 5kΩ, and the two resistance to ground equal, measured between (15), Resistance is zero.