此机上电开机后控制板显示一闪即灭。用MC—SH2115控制板代换试机。出现代码E7故障,测整机高压供电电路c4对地电压为+305V,正常。测低压供电电路C92对地电压为+18V.正常。测C91对地电压为+5v。正常。测电网电压检测电路取样电阻R7(240kΩ/1w)对地+23v电压偏低(正常为十3v)。用10kΩ挡检测发现电阻R7(240kΩ//1w)变值,从而造成了cPu芯片(VIN)识别欠电压而自动保护关机。更换电阻R7后整机恢复正常 |
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