交流声通常来自过载的电源供给器或有故障的放大器电源供给器。正规的故障查找需要使用一个优质的交、直流电压表,一个万用表和一个优质的可读取交流声数值的信号电平表。没有必要使用有效值读数的交流电压表;要精确地测量交流电压时需要用这种表,但是根据我们的经验,有一个相当好的非有效值读数的交流电压表就足够了,而且费用也小得多。一个技术人员一旦获得了当电压正常时交流表头上的读数应当是多少这种“感觉”以后,就不一定要使用真正的 The hum usually comes from an overloaded power supply or a faulty amplifier power supply. Formal troubleshooting requires the use of a good AC and DC voltmeter, a multimeter, and a good signal level meter that reads acoustical values. It is not necessary to use an AC voltmeter with rms readings; it is necessary to accurately measure the AC voltage, but in our experience it is sufficient to have a fairly good ac voltmeter for non-RMS readings Much smaller. Once a technician has gained the “feel” of how much reading should be on the meter head when the voltage is normal, it is not necessary to use a real