JL Audio HD900/5 owner manual Status LED / Protection Circuitry

“Status” LED / Protection Circuitry

There is a single multi-color LED on the control panel of the amplifier to indicate the amplifier’s operating status. This LED’s behavior is as follows:

1)Flashing Green: amplifier is powering up, audio output is muted.

2)Constant Green: amplifier is on and functioning normally, audio output is active.

3)Constant Red: lights to indicate that the amplifier has exceeded its safe operating temperature, putting the amplifier into a self- protection mode, which temporarily reduces the peak power output of the amplifier. The red light will turn green and the amplifier will return to full-power operating mode when its temperature returns to a safe level.

3)Constant Amber (yellow): lights to indicate that at least one channel is in overcurrent protection mode. This could mean that the impedance of the speaker load connected to the amplifier is lower than the optimum load impedance range for the amplifier. When this light is on, a protection circuit engages and reduces the power output of the channel(s) experiencing the problem. This can manifest itself as audible distortion.

The amber indicator will also light when a short-circuit is detected in the speaker wiring (this can be a short between the positive and negative speaker wires or between either speaker wire and the vehicle chassis). This can be used to diagnose a short-circuit by only connecting one of the amplifier sections at a time (“Front” or “Rear” or “Sub” channels). The amber LED will light when you connect the section that is experiencing the problem and turn the volume up. Note that a short in the speaker wiring may show an alternating red/green status light with no signal (volume down).

4)Alternating Red and Green: lights to indicate that the amplifier is experiencing a fault that may require service of the amplifier, its wiring or the vehicle’s charging system. Audio is muted when this fault occurs. The most likely cause of this fault is a low supply voltage condition. If battery voltage drops below 8.5 volts at any point, the amplifier (except for the “Status” LED) will shut itself off to protect itself and the vehicle’s charging system. If the Remote Turn-On voltage drops below 6 volts, the “Status” LED will also turn off.

The amplifier will turn back on automatically when voltage climbs back above 9 volts. This shut-down and turn-on behavior may happen in a rapid cycle when bass-heavy program material causes a weak charging system to momentarily dip too low. If this is happening in your system, have your charging system inspected to make sure it is working properly.

If no problem is found with the supply voltage to the amplifier and you are still seeing alternating Red and Green on the “Status” LED, check that there are no short-circuits to chassis ground in any of the speaker wiring in the vehicle. Disconnect speaker connectors from the amplifier one-by-one to check.

If no problem is found with the supply or remote voltage, disconnect everything except power/ground/remote. If the amplifier is then turned on and displays an alternating red- green, the amplifier needs service.

For more information on troubleshooting this amplifier, refer to Appendix D (pages 20, 21).

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