故障一：交流开机即烧保险，电池供电正常。分析检修：电池供电正常，说明仪器主机正常，拆下保险管，发现管壁被镀上一层熔化金属，短路严重，且故障部位一般较靠前。由于本机未附电路图，检修极不方便，须小心仔细。开盖仔细观察，发现电阻R808、R807有烧焦的痕迹，随着电路 Fault 1: AC start-up burns insurance, battery power is normal. Analysis and maintenance: The battery power is normal, indicating that the instrument host is normal, remove the fuse, and found that the pipe wall is coated with a layer of molten metal, the short circuit is serious, and the fault site is generally more forward. Since this unit does not have a circuit diagram, maintenance is extremely inconvenient and care must be taken. Open the lid and observe carefully and find that the resistors R808, R807 have scorch marks, along with the circuit