SFB SERIES AMPLIFIER OWNER’S MANUAL version 01/21 v2
All Sundown Audio amplifiers have multi-layer protection features to prevent damage from misuse or faulty
conditions to ensure long lasting life of your investment. If the unit senses excessive heat, short circuited
speakers, overload, or voltage fluctuation outside of the working range the protection indicator light will turn red
and the unit will turn off. In order to solve this problem, you should turn all levels down, power off the unit, then
carefully check the installation for wiring mistakes or shorts. If the amplifier is excessively warm the protection
light will not turn on as the unit will turn off to protect itself from overheating. Let the unit cool down for 30
minutes and try again. If the unit works, try moving the amplifier or make sure nothing is covering it so it can
vent heat off of the heatsink. Before you remove or uninstall the amplifier, refer to the list below for suggested
solutions.
Amplifier Doesn’t Turn On or No Output
Check the fuse(s), not just visually, but with a continuity meter and all 12+ volt, remote and ground
connection. Make sure you have 13+ volts. It is possible for a fuse to have poor internal connections,
take the fuse out of the holder for the testing.
Check the input signal from the source unit using an AC voltmeter to measure the voltage while it’s
being played. The voltage should be from 0.2 to 6.0 volts from the RCA cables.
Check the output of the amplifier, test for output at the speaker outputs of the amplifier.
Check to ensure that the speaker wires are making a good connection to the amplifier and the
subwoofers.
Amplifier Goes Into Protection
Check shorts on speaker wires or open coil.
Check input voltage from RCA, if DC signal is over 4 volts, the amplifier will go into protect. Remove
and reset the power to the unit to check if it will turn on.
Check impedance to make sure it’s over the minimum load, see the specification charts in this manual
for the minimums of your specific amp.
Check input voltage. The amplifiers covered in this manual have a working range of 10.5 to 15.5 volts.
Check chassis ground and remote using same ground.
Distorted / Attenuated / Noise Sound
Check the chassis ground connections of all audio equipment.
Check amplifier controls for errors, input level or crossover setting.
Check the speaker wires for a possible short, either between the positive and negative leads or
between a speaker lead and the vehicle’s chassis ground.
Check the nominal load impedance to verify that the amplifier is driving a load equal to or greater than
the specified minimums, see the specification charts in this manual for the minimums of your specific
amp.
Check the input signal and input signal cables to make sure signal is present at the amplifier inputs and
the cables are not pinched or loose. It may be helpful to try a different set of cables and / or a different
signal source to be sure.
Check speaker wiring for reverse polarity.
If you hear a pulsing sound from your speakers, it means that there is something being overdriven.
This could be due to a gain being set too high or a speaker impedance being too low, see the
specification charts in this manual for the minimums of your specific amp.
TROUBLESHOOTING
