QSC Audio PL224A, PL230A Problem Distorted Sound, Problem No Channel Separation, Problem Hiss

TROUBLESHOOTING: DISTORTION, NO CHANNEL SEPARATION, HUM, HISS, FEEDBACK

PROBLEM: DISTORTED SOUND

• INDICATION: CLIP LED FLASHING

•If the red CLIP indicator flashes before all three signal indicators do, the load impedance is abnormally low or shorted. Unplug each speaker one-by-one at the amplifier. 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 INDICATOR NOT FLASHING

•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 amplifier gain controls at least halfway up so that the source does not have to be overdriven.

PROBLEM: NO CHANNEL SEPARATION

•Check the yellow PARALLEL or orange BRIDGE MONO LEDs on the front panel, which indicate the switch settings on the back of the amplifier. Neither should be lit in dual-channel, bi-amp, or stereo use where different signals go to each channel. Make sure the "Parallel Input" and "Bridge Mode" switches are OFF.

•Make sure other equipment in the signal path, such as mixers, preamps, etc., is set for stereo, not mono.

PROBLEM: CH 1 IS ALL LOW FREQUENCY MATERIAL & CH 2 IS ALL HIGH FREQUENCY MATERIAL

•Check that the BI-AMPLED on the front panel is not illuminated. If it is, the MODE switch on the rear panel is in the BI-AMPposition. Move the MODE switch to the 2 CH position. This assumes you do not want to be in BI-AMP mode and that you are operating in a 2 channel mode.

PROBLEM: HISS

•Unplug the amplifier input to confirm that the hiss is coming from the source or a device upstream; erratic or popping noises indicate an electronic fault in the offending unit.

•To keep the normal noise floor low, operate the primary signal source at full level, without clipping, and avoid boosting the signal further between the source and the amplifier.

PROBLEM: SQUEALS AND FEEDBACK

•Microphone feedback should be controlled with mixer controls. If noise continues to build up with zero mic gain, there is a serious fault in the signal processors or cables. Working in succession from the signal source towards the amplifier, check each device in the signal path by reducing its gain or unplugging it.

PROBLEM: HUM

•The PowerLightTM supply eliminates internal hum fields, but transformers in other magnetic devices may cause hum. Move cabling and signal sources to identify "hot spots" in the system; then avoid those spots. Cables with faulty shielding are a common entry point for hum. Use top quality cabling.

Magnetic field from power supplies in equipment can induce hum into cabling that is located in the field. If hum is a problem, try relocating cabling so that is away from power supplies, transformers and other magnetic field producing devices.

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