QSC CMX 300Va, User Manual, Page: 17 / 100

17
EN
Troubleshooting
Problem: No Sound
Indication:
POWER indicator not lit
Check the AC plug. Also check the circuit breaker on the rear panel.
Confi rm that the AC outlet works by plugging in another device. If too many amplifi ers are used on one outlet, the building’s
circuit breaker may trip and shut off power.
An overload in Bridged Mono mode may cause the amplifi er to click off for several seconds. Check the load impedance (4

minimum), or
reduce signal level.
An amplifi er which keeps shutting off may have a serious internal fault. Turn it off, remove AC
power, and have the amplifi er serviced by a qualifi ed technician.
Indication:
SIGNAL LED responding to signal level
If the green SIGNAL indicators are lighting normally, the fault is somewhere between the amp
and the speaker. Check the speaker wiring for breaks. Try another speaker and cable.
Indication: SIGNAL LED not lit
If the green POWER indicator LED is lit and the fan is running, yet the signal LEDs indicate no
signal, check the input. Make sure the signal source is operating and try another input cable.
Connect the source to another channel or amplifi er to confi rm its operation.
Indication: CLIP LED fl ashing
If the red CLIP indicator fl ashes when signal is applied, the amplifi er output may be shorted.
Check the speaker wiring for stray strands or breaks in the insulation.
Indication:
CLIP LEDs bright and steady
The amplifi er is in protective muting.
One second of muting is normal when the amp is turned on or off.
Overheating will cause protective muting. The fan will be running at full speed and the chassis
will be hot to the touch; sound should resume within a minute as the amplifi er cools to a safe
operating temperature. Check for proper ventilation. If the fan isn’t running at all, the amplifi er
requires servicing.
Problem: Distorted Sound
Indication:
CLIP LED fl ashing
If the red CLIP indicator fl ashes before the signal indicator does, the load impedance is abnormally low or shorted. Unplug each speaker one-by-one
at the amplifi er. If the CLIP LED goes out when you disconnect a cable, that cable or speaker is
shorted. Try another cable and speaker to locate the fault.
Indication: CLIP LED not fl ashing
This could be caused by a faulty speaker or loose connection. Check the wiring and try
another speaker.
The signal source may be clipping. Keep the amplifi er attenuation controls at mid point so that
the source does not have to be overdriven.
— Figure 37 —
= lit
= blinking
= off
KEY
— Figure 38 —
POWER SIG SIG CLIP CLIP
— Figure 39 —
POWER SIG SIG CLIP CLIP
— Figure 40 —
POWER SIG SIG CLIP CLIP
— Figure 41 —
POWER SIG SIG CLIP CLIP
— Figure 42 —
POWER SIG SIG CLIP CLIP
— Figure 43 —
POWER SIG SIG CLIP CLIP
— Figure 44 —
POWER SIG SIG CLIP CLIP