6.TROUBLESHOOTING TIPS
NO POWER
Check the connections between the mixer and the power supply and the external AC power supply.
Examine the 4-pin connector as shown on page 22.
Check the wall outlet.
NO SOUND
Make sure the MIC/Line switch is in the proper position. (This is the most likely cause.)
Make sure both the master and channel input controls are turned up.
Check that the source signal cable(s) is properly connected and undamaged.
Adjust Input Gain/Trim Control potentiometer(s) to increase gain.
If there is still no sound, try changing input source(s) to different channel(s).
DISTORTED SOUND
Turn down the master volume control. If distortion persists, input channel(s) gain is the likely cause.
Check position of all line/MIC switches.
Determine the distorting input channel(s) by checking them one at a time.
Decrease gain of input channel(s) causing distortion by turning the screw on the rear panel.
EXCESSIVE HISS or HUM
Hiss: Make sure the volume control knobs for all the unused channels are turned all the way off
(i.e., at the 7 o'clock position).
Make sure that all unused input channels have the MIC/Line switch in the Line position.
Make sure the MIC/Line switch is in the correct position for both the inputs and the main output.
Hum: MIC lines can easily cause hum. Make sure to locate them away from vibration and magnetic field
sources (motors, power supplies and lines, and data lines).
Check MIC lines, especially the shield, for damage.
Another common source of hum is a ground loop, which can result from connecting two or more powered
devices together.
Turn both the Main and Auxiliary volume controls down. If the hum is still present, the ground loop or
other cause is not in the mixer, but in the devices that come after it in the audio path or in the connection
between the mixer and following equipment. (If the hum disappears, then the cause is either in the mixer
or in one of the inputs to the mixer. Turn each of the volume controls [both the individual input channels
and the two buses] down independently, to determine which one is the source of the hum.)
Check for unbalanced connections; use balanced connections, if possible. For all unbalanced
connections, try disconnecting the signal line ground to eliminate multiple ground paths.
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