Friday, December 18, 2015

INFINITY Reference Series 5760a car amplifier troubleshooting and circuit diagram

INFINITY  5760a

Test Conditions
# All tests to be done, unless otherwise specified, from 10Hz to 47KHz and 302Hz at 14.4V DC into 4 ohm loads and adjust the units gain so that with a .775 volt input signal the unit is at Its maximum rated output. All measurements will be done using an Audio precision system one and the supply voltage.
# An A+ line voltage of 14.4V DC shall be applied to the unit under test for all measurements unless otherwise specified. The voltage applied to the unit shall be measured at the power connection on the Amplifier.
# Signal Source
Unless otherwise specified, all tests shall be conducted with the Audio Signal Generator output configured to be balanced, less than or equal to 50 ohm source impedance, and floating. The signal source "GND" shall be connected to the Amplifier PWR GND at the Amplifier.
# Output Load
Unless otherwise specified, all tests shall be conducted with 4 ohm resistive loads having less than 10% reactive components at any frequency below 47KHz and 302Hz. Each resistor shall have a value that remains within 1 % while dissipating the rated output of the unit under test.
# Power Indicator Green LED steadily illuminates for normal operation. Illuminates up Red LED blinks when protection circuitry is engaged, and during power up.
GROUND CONNECTION
Connect the amplifier’s Ground (GND) terminal to a solid point on the vehicle’s metal chassis, as close to the amplifier as possible. Refer to the chart below to determine minimum wire-gauge size. Sand away any paint from this location; use a star-type-lock washer to secure the connection.
POWER CONNECTION
Connect a wire (see chart at right for appropriate gauge) directly to the vehicle’s positive battery terminal, and install an appropriate fuse holder within 18" of the battery terminal. Do not install the fuse at this time. Route the wire to the amplifier’s location, and connect it to the amplifier’s positive (+12V) terminal. Be sure to use appropriate grommets whenever routing wires through the firewall or other sheet metal. Failure to adequately protect the positive wire from potential damage may result in a vehicle fire. When you are done routing and connecting this wire to the battery and to the amplifier, you may install the fuse at the battery. The fuse value should be selected based on total amplifier-current draw; see chart at right.
SETTING INPUT SENSITIVITY
1. Initially turn the INPUT LEVEL control(s) to minimum (counterclockwise).
2. Reconnect the (–) negative lead to the vehicle’s battery. Apply power to the audio system and play a dynamic music track.
3. On the source unit, increase the volume control to 3/4 volume. Slowly increase the INPUT LEVEL control(s) toward three o’clock until you hear slight distortion in the music. Then reduce the INPUT LEVEL slightly until distortion is no longer heard
SETTING THE BASS BOOST
The 7520a, 7540a and 5760a are all equipped with a bass-boost control. This allows you to enhance the bass output of your system at 50Hz up to 12dB.
NOTE: Only rear channels of the 7540a are affected by the bass boost control.
AUX OUTPUT
Reference amplifiers (except 5760a) are equipped with full-range outputs that can be used to connect additional amplifiers.
NOTE: When using the low- or high-level inputs, the AUX outputs can be used to pass a full-range line-level signal to another amplifier.
TROUBLESHOOTING
PROBLEM:
No audio (POWER LED is off). CAUSE and SOLUTION:
No voltage at BATT+ and/or REM terminals, or bad or no ground connection. Check voltages at amplifier terminals with VOM.
PROBLEM:
No audio (PROTECT LED flashes every 4 seconds).
CAUSE and SOLUTION:
DC voltage on amplifier output. Amplifier may need service; see enclosed warranty card for service information.
PROBLEM:
No audio (PROTECT LED is on).
CAUSE and SOLUTION:
Amplifier is overheated. Make sure amplifier cooling is not blocked at mounting location; verify that speaker-system impedance is within specified limits.
PROBLEM:
No audio (PROTECT and POWER LEDs flash).
CAUSE and SOLUTION:
Voltage less than 9V on BATT+ connection. Check vehicle charging system.
PROBLEM:
No audio (PROTECT LED is on).
CAUSE and SOLUTION:
Voltage greater than 16V or less than 8.5V on BATT+ connection. Check vehicle charging system.
PROBLEM:
Distorted audio.
CAUSE and SOLUTION:
Input sensitivity is not set properly, or amplifier or source unit is defective. Check INPUT LEVEL setting, or check speaker wires for shorts or grounds.
PROBLEM:
Distorted audio (PROTECT LED flashes).
CAUSE and SOLUTION:
Short circuit in speaker or wire. Remove speaker leads one at a time to locate shorted speaker or wire, then repair.
PROBLEM:
Music lacks “punch. ”
CAUSE and SOLUTION:
Speakers are not connected properly. Check speaker connections for proper polarity.
POWER AMP CIRCUIT DIAGRAM 
CLICK ON THE IMAGE TO ZOOM IN