Legacy Car Audio L A 3 7 0 - Manual (Page 7)

troubleshooting
Troubleshooting
Speaker Connections
2 CH Mono-Bridged Output
Bridged Mono Output 2 CH Stereo plus
Mono-Bridged
Subwoofer Output
TROUBLESHOOTING
11
Amplifier will not power up.
• Check for good ground connection.
• Check that remote DC terminal has at least +12v DC.
• Check that there is battery power on the + terminal.
• Check all fuses.
• Check that Protection LED is not lit. If it is lit, shut off amplifier
briefly and then repower it.
High hiss or engine noise (alternator whine) in
speakers.
• Disconnect all RCA inputs to the amplifier(s) – if hiss/noise
disappears, then plug in the component driving the amplifier
and unplug its inputs. If hiss/noise disappears, go on until the
faulty/noisy component is found.
• It is best to set the amplifier's input level as insensitive as
possible. The best subjective S/N ratio is obtainable this way.
Try to drive as high a signal level from the head unit as possible.
Protection LED comes on when the amplifier is
powered up.
• Check for shorts on speaker leads.
• Check that the volume control on the head unit is turned
down low.
• Remove speaker leads, and reset the amplifier. If the
Protection LED still comes on, then the amplifier is faulty.
Amplifier(s) gets very hot.
• Check that the minimum speaker impedance for that model
is correct.
• Check for speaker shorts.
• Check that there is good airflow around the amplifier. In
some applications, an external cooling fan may be required.
Distorted sound
• Check that the Level control(s) is set to match the signal
level of the head unit.
• Check that all crossover frequencies are properly set.
• Check for shorts on the speaker leads.
High squeal noise from speakers.
• This is almost always caused by a poorly-grounded RCA
patch cord.
Before removing your amplifier, refer to the list below
and follow the suggested procedures. Always test the
speakers and their wires first.
speakers
L
Mono
Subwoofer
MINIMUM
SPEAKER
IMPEDANCE
4 OHMS! R
speaker
MINIMUM
SPEAKER
IMPEDANCE
4 OHMS!
speakers
L R
MINIMUM
SPEAKER
IMPEDANCE
4 OHMS!
LA
670
LA 870
4CH AMPS
2CH AMPS
LA 370
LA
470
LA
570
LA
770
LA
970
LA 1470
LA
1870
LA
2070
4CH AMPS
LA
670
LA
870