查场扫描集成块LA7840供电正常,测LA76832第23脚场激励2.2V正常,换LA7840,故障依旧.检查LA7840各脚电压,发现4脚2.5V正常,5脚1.5V偏低,查5脚外围电路,发现5脚对地一电容C301(1000PF)漏电,更换后故障排除。 |
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