推荐回答(1个)
1、在故障点找到后,换元器件之前一定要把元器件所在部分的电路及印制电路板图搞 清楚,并把元器件各端子的含义及连接位置等记载下来,以备后查。
2、使用逻辑电笔和示波器等仪表检修时应注意,检测仪表一般有电源及信号输人两部
分连线,如逻辑电笔上述两类连线都有,电源线一定要接在待测元器件的电源上。要注意:
在一个印制电路板内一般都有两种以上电源,如汽车微机控制系统就有输人电源(12V)、
芯片工作电源(5V),所以一定要接对,否则轻则影响待测元器件及仪器的寿命,重则烧坏
它们。在使用仪表测试时,不能使探针(探头)同时接触两个端子,因为这种情况的实质 是在加电情况下形成短路,这样有可能损坏被测元器件或连线。如有条件可采用压接探头,
即探头在没有压到待测元器件的部位时,它被绝缘材料(如橡皮一类物质)包围,在被测 点用力压下时探头的头才被压出与被测点接触。
3、 不要带电插拔各类控制板和插头,这容易造成短路;也容易产生较强的感应电动势。
在断开电源的瞬时,电流变化率非常大,产生的自感电动势有时高达几千伏,高的瞬时电压 通过电源线加到微机系统,可能造成保护装置的损坏,进而使系统受损。
4、 蓄电池的任一根线都不能随便断开。在跨接起动其他车辆或用其他车辆跨接起动本
车时,须先断开点火开关(即切断数据微机电源),才能装拆跨接连线。
5、 强的电磁场不能靠近微机,例如收录机、电视机的扬声器,一般都是用较强的永久
磁铁做成的,如果距微机太近,它的磁场会使微机系统中的有关零部件损坏。另外在车上使
用电弧焊时,电弧本身是一个频谱比较宽的电磁波发射源,且强度较高,距离又近,如微机
正在工作,轻则使程序不能正常运行,重则会损坏微机的有关零件,所以在电弧焊以前应把 微机系统电源切断。
6、
在对微机系统检测或更换芯片时,操作人员一定要将身体接地,即带上搭铁金属带,将其一头缠在手腕上,另一头夹到车上,这样才能将人体产生的静电传人车体,防止对微机
零件的侵害。
7、应用高阻抗的仪表检测微机系统。如果用低阻抗的仪表对微机系统进行测量,就
相当于在微机的测试点并联一个较大的负载,可能因超负荷而损坏微机系统。有的检测 仪表中的电源电压高于微机系统的工作电压时,更不能直接用来对其进行检测。一般不
能用低阻抗的万用表对传感器进行测量,更不能用测试灯去测量微机连接的任何电气装置。
8、微机要使用独立的供电电路。汽车上电气设备较多,而且不少是脉冲式供电,这样
在接线和搭铁电阻上就有大量的干扰信号存在。为了使微机系统和附属装置能正常工作,一
般它们的供电电路和搭铁插头通常是和蓄电池主要供电系统的插头分开的,称为无噪声隔离
插头。其他辅助电气设备都不能接到这一套独立的供电电路和搭铁插头上,有时在维修过程
中,检测仪表也不能接上。否则,微机就会受到其他电器的共线干扰,严重时会使微机无法 正常工作。
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