QSC Audio HPR122i - Manual (Page 13)

13
SIGNAL Indicator LED
The green SIGNAL indicator alerts the user to the presence of an input signal to the
HPR loudspeaker.
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 oscil-
lations 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 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 nor-
mally due to excessive volume and may be accompanied by audible distortion.
• If the loudspeaker mutes repeatedly during output peaks, there may be a component
fault; AC power should be removed and the loudspeaker 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 sec-
onds, and the red indicator will go out.
• If the power module overheats, the first response is to trigger limiting, to reduce vol-
ume and limit further temperature rise. This results in a steady half-bright illumina-
tion 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.
LED indicators.