Power down the mixer, and unplug its main power cable from the nearest wall receptacle. Disconnect all instrument, speaker and microphone cables from the inputs and outputs on the back of the mixer.
Remove all knobs from the mixer by pulling straight up on each knob until it comes free from the mixer. Divide up and store the knobs in plastic bags according to the section they were removed from. This helps alleviate confusion for when you put the mixer back together.
Remove the Phillips-head screws from the mixer's top cover. Grasp each side of the top cover, and lift it off the mixer to reveal the internal contents of the mixer. You may need to pry up the top cover with a flat-head screwdriver if you have a hard time lifting the cover by hand.
Lay the top cover facedown next to the open mixer.