Problem: Hum; 问题：噪声; Problem: Hiss; 问题：嘶嘶声 - QSC DCA1222 User Manual

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TROUBLESHOOTING

Problem: hum

• The PowerLight supply eliminates internal hum fi elds, but AC transformers
in other devices may cause hum. Move cabling and signal sources to iden-
tify "hot spots" in the system. Cables with faulty shielding are a frequent
entry point for hum.

Problem: hiss

• Unplug the amplifi er input to confi rm that the hiss is coming from the
source or a device upstream; erratic or popping noises indicate an elec-
tronic fault in the offending unit.
• To keep the normal noise fl oor low, operate the primary signal source at full
level, without clipping, and avoid boosting the signal further between the
source and the amplifi er.

Problem: squeals and feedback

• Microphone feedback should be controlled with mixer controls. If noise
continues to build up with zero mic gain, there is a serious fault in the
signal processors or cables. Working in succession from the signal source
towards the amplifi er, check each device in the signal path by reducing its
gain or unplugging it.
故障排除
问题：噪声
• PowerLight 电源消除了内部噪音磁场，但其他设备的 AC 转换
器可以会导致噪声。移动线缆和信号源，以识别系统中的"热
点"。噪声经常从保护层有缺陷的线缆处进入。
问题：嘶嘶声
• 拔掉放大器输入端，检查嘶嘶声是来自源还是来自设备上游；
奇怪的声音或砰砰声说明该故障单元中的电子出现问题。
• 要保持较低的正常固有噪声电平，请在完整级别上操作主要信
号源而无需削波，并避免将信号提高到源与放大器之间的更深
处。
问题：刺耳声和回声
• 应通过混频器控件来控制麦克风的回声。如果将麦克风增益调
至零时，噪声依然持续，则说明信号处理器或线缆有严重故
障。持续从信号源朝放大器作用时，请通过减小其增益或将其
拔掉的方式检查信号路径中的每个设备。