JL Audio M500/3 Owner's Manual

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12  |  JL Audio - M500/3 Owner’s Manual  
STATUS LED / PROTECTION CIRCUITRY
There is a single multi-color LED on the top 
surface of the amplifier to indicate the amplifier’s 
operating status. 
Ò
 
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: Indicates that the amplifier has 
exceeded its safe operating temperature, putting 
the amplifier into a self-protection mode, which 
reduces the peak power output of the amplifier. 
When its temperature returns to a safe level, the 
red light will return to green and the amplifier 
will return to full-power operating mode.
4) Constant Amber (yellow): Indicates that 
an over-current condition has occurred and 
is accompanied by a muting of the affected 
channel(s). Because the muting behavior may be 
very short in duration, it may manifest itself as 
an audible, repetitive ticking noise in the output. 
Over-current conditions can be caused by a 
speaker impedance lower than the optimum load 
impedance range for the amplifier or a short-
circuit in the speaker wiring. The latter can result 
from a short circuit between the positive and 
negative speaker wires or between either speaker 
wire and the vessel chassis. The “Status LED” 
will remain amber for a few seconds, even if the 
over-current condition is of a very short duration. 
This functionality can be used to diagnose a 
short-circuit by only connecting one channel at 
a time. The “Status LED” will turn amber when 
you connect the channel that is experiencing the 
problem and turn the volume up. 
5) LED off / Amplifier Shuts Off Unexpectedly
The only condition that will shut down
an undamaged M500/3 completely is if battery 
voltage or remote turn-on voltage drops below 
10 volts. The “Status LED” will turn off when 
this occurs. The amplifier will turn back on 
when voltage climbs back above 11 volts. If this 
is happening in your system, have your charging 
system and power wiring inspected.
For more information on troubleshooting this 
amplifier, refer to Appendix D (pages 16, 17).