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三、检修故障实例例1 故障现象:开机“三无”,指示灯不亮。检修:指示灯不亮,说明电源电路没有工作。拆机查看保险已开路损坏,并且发黑,查Q801、Q802、Q803、Q804均击穿,其他元件无明显损坏,把损坏的元件换新后接假负载试机,主电压为98V,说明副脉宽调控电路已正常,接通电源开机,图像、伴音正常。例2 故障现象:开机“三无”,机内有“咔咔”响声。检修:该机为“转修机”,接假负载试机,还是有“咔咔”响声,仔细听响声是因继电器RL801不断吸合发出的,测主电压和42V端及20V端输出电压,随着继电器的不断吸合,分别在3～0V、44～0V、23～0V之
Third, troubleshooting example 1 fault symptoms: boot “three no” indicator light does not shine. Overhaul: The indicator light is off, indicating that the power circuit is not working. Disassemble to see the insurance has been open circuit damage, and black, check Q801, Q802, Q803, Q804 are breakdown, no obvious damage to other components, the damaged components replaced false load test machine, the main voltage of 98V, Pulse width modulation circuit has been normal, turn on the power boot, images, sound normal. Example 2 Symptom: boot “three noes”, the machine has “Kaka” sound. Overhaul: The machine is “turn machine”, then leave the load test machine, or “Kaka” sound, carefully listen to the sound is due to the relay RL801 constantly issued, measured the main voltage and 42V-side and 20V-side output voltage, With the continuous pull of the relay, respectively, in 3 ~ 0V, 44 ~ 0V, 23 ~ 0V