Troubleshooting - QSC PL218A User Manual

TROUBLESHOOTING: NO SOUND
Problem: NO SOUND
• INDICATION: POWER INDICATOR NOT LIT
• Check the AC plug.
• Confirm that the AC outlet works by plugging in another device. If too many amplifiers are used on one outlet, the
building's circuit breaker may trip and shut off power.
• An overload in bridge mode may cause the amplifier to click off for three seconds, indicated by the half-bright
POWER LED, followed by a normal restart cycle. Check the load impedance (4 ohms minimum), or reduce signal
level.
• An amplifier which keeps shutting off may have a serious internal fault. Turn it off, remove AC power, and have the
amplifier serviced by a qualified technician.
• INDICATION: SIGNAL LED NOT LIT
• Ensure that the DATAPORT INPUT SIGNAL switch is in the proper position. If you are using the XLR or terminal
block inputs, it should be in the OFF position. If you are using the DATAPORT for your input signal, the switch should
be set to PRE PROC or POST PROC.
• If the green POWER indicator LED is at full brightness, 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
amplifier to confirm its operation.
• INDICATION: SIGNAL LEDS RESPONDING TO SIGNAL LEVEL
• If the green SIGNAL, -20 dB, and -10 dB 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: CLIP LEDS BRIGHT AND STEADY
The amplifier 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 amplifier cools to a safe operating temperature. Check for
proper ventilation. If the fan isn't running at all, the amplifier requires servicing.
• INDICATION: CLIP LED FLASHING
• If the red CLIP indicator flashes when signal is applied, the amplifier output may be shorted. Check the speaker
wiring for stray strands or breaks in the insulation.
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