QSC Audio HPR181W, HPR153F, HPR151W, HPR152F user manual Signal Indicator LED, Limit Indicator LED

SIGNAL Indicator LED

The green SIGNAL indicator alerts the user to the presence of an input signal to the HPR loud- speaker.

Normal Indication

The green SIGNAL indicator illuminates when the input signal exceeds -25 dB.

If No Indication

Check Gain settings and increase gain if necessary. Check input connections and audio source for signal. If the red LIMIT LED illuminates, refer to the LIMIT indicator section, below.

Abnormal Indication

If the green SIGNAL LED illuminates with no signal input, there may be system oscillations or some other malfunction. Disconnect the input or fully reduce the gain. If the green SIGNAL LED remains on, the amp may need servicing.

LIMIT Indicator LED

The red LIMIT indicator alerts the user to several abnormal conditions within the HPR loud- speaker:

Continuous Bright Red Light

•Indicates protective mute mode.

•The speaker normally passes through muting for several seconds after applying power, after which the light should go out, and sound should be heard.

•If the speaker enters Mute during operation, it has either overheated or developed a fault.

•Overheating should correct itself within 1-2 minutes, after which sound should resume. See below for a full explanation of thermal protection.

•Short periods of muting indicate a component fault. In this case AC power should be removed and the speaker serviced.

Momentary Bright Red Flashes

•During operation, bright flashing indicates clipping (overdrive distortion).

•This is normally due to excessive volume, and will likely be accompanied by audible distortion.

•If the speaker mutes repeatedly during peaks, there may be a component fault. AC power should be removed and the speaker serviced.

Continuous Half-bright Light

•Indicates that the internal limiter is reducing gain, due to prolonged clipping and/or excessive temperature.

•After several seconds of severe clipping, the limiter will reduce power to protect the speaker and improve the sound. This results in a steady, half-bright red indication. Any further clipping will still result in bright flashes on top of the steady half-bright indication. When the program level is reduced, the limiter will clear after several seconds, and the red indicator will go out.

•If the power module overheats, the first response is to trigger limiting, to reduce volume and limit further temperature rise. This results in a steady half-bright illumination that does not clear even after reducing program level. It may take several minutes for temperature to drop and clear the limiter. During this time, the exposed heat sink will feel uncomfortably hot to the touch. If overheating continues, the amplifier will ultimately mute, resulting in a full-bright red indication. When muting clears, the amplifier will resume operation, with thermal limiting still active until it further cools off.

•Overheating is usually caused by excessive ambient temperature, since the internal temperature rise of the power module is relatively low. Protect the speaker from excessive temperatures, such as being placed over a heater vent, or allowing direct sunlight to impinge upon the heat sink surface.

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