L-ACOUSTICS LA15a 115V Manual V1.0 27/01/2003
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8.5 AC MAINS VOLTAGE PROTECTION
If the AC mains voltage is outside the allowed operational voltage (over or under voltage), the power
supply will automatically shut down. Once the mains voltage is above the minimum start voltage and
below its maximum operating voltage the amplifier will restart. It takes a few seconds for the amplifier
to self-check (this is known as the soft or slow start sequence), the gain will slowly and gradually be
increased back to the previously set level and the fans will blow at high speed before going into idle. The
two green ”ON” LEDs indicate when the power supply is operating properly.
8.6 DC PROTECTION
There are two types of DC protection: 1) Fuses on the supply branches of each channel; 2) DC crowbar
protection that shorts the output if more than 10 volts DC are detected on the outputs. Both these
circuits are activated if a DC level is detected on either channel.
9. MAINTENANCE
Under normal use your power amplifier should provide years of trouble-free service. The only user
maintenance required is to vacuum the front grill periodically.
In some extreme cases it may be necessary for authorized service personnel to clean the inside of the
amplifier. This is usually necessary after prolonged use in environments where cracked-oil smoke
machines are present.
If you are using your amplifier for heavy duty use, e.g. concert touring, it is recommended that you
have your amplifier serviced every 3 years, purely as a preventative measure.
9.1 TROUBLESHOOTING
These are typical things to check if you think your amplifier is faulty:
Fault: No output.
If the output bar graph is functioning there is nothing wrong with the amplifier. The likely cause is an
unsecured Speakon connector (at the amplifier output terminals or loudspeaker).
Check also that VHF protection is not activated. If it is, remove possible high frequency oscillations
from the relevant input.
Fault: The amplifier goes into thermal protection when driven at low level.
Check that nothing causes a short circuit at the amplifier's output, e.g. faulty cabling or a loudspeaker
component short circuit in the voice coil.
Fault: The amplifier goes into protection with the power indicators off.
Check that the AC line voltage is within the amplifier’s operating range: 65-135 V @ 115 V (or 130-
265 V @ 230 V). Over/under-voltage protection may have occurred. If the amplifier is connected by
mistake to a 3 phase supply, an internal non-resettable fuse or resistor may have blown (return the
amplifier to your supplier for service).
Fault: The amplifier does not respond even after checking above items.
In the unlikely event of a non-user rectifiable fault, return the amplifier to your supplier or an
approved service centre (see Section 11).
L-ACOUSTICS cannot be held responsible for damage or injury as a result of the top or
bottom covers being removed.
