Powered audio mixers have a built-in amplifier, and are commonly used for live music performances or venues. If not properly cared for, they can accumulate dust and debris. This can cause the knobs on the mixer to make crackling sounds, or damage the audio input connectors on the mixer. Repairing your powered mixer means dismantling the mixer, and cleaning the internal electronic components. This usually includes your mixer's circuit boards, audio connectors and transistors.
Turn off the mixer, and unplug its main power cord. Disconnect all microphone, instrument and RCA cables from the connectors on the mixer.
Remove the knobs from each section of the mixer, and store the knobs in individual plastic bags according to section. Most knobs can be easily pulled from the mixer. For instance, store the volume knobs in one plastic bag, and the equalization knobs in another plastic bag.
Loosen and remove the Phillips-head screws along the mixer's external housing. Grasp each side of the top housing, and lift it off of the rest of the mixer to reveal its internal components.
Use a can of compressed air to blow out all loose dust and debris from inside the mixer. Apply some rubbing alcohol to a clean wash cloth. Wipe down the circuit boards, transistors and audio connectors from inside the mixer.
Use a wrench or pair of vice grips to tighten all loose audio connectors inside the mixer. Replace the mixer's top cover, and re-fasten all Phillips-head screws to the mixer's housing. Replace all knobs and buttons.
All major electrical repairs should be reserved for a seasoned audio electronics technician. Attempting these repairs yourself will void your mixer's warranty.