Ecler PAM2000, Service Manual

Page: 68 / 107

FREQUENCY RESPONSE
0.5V input signal.
Verify frequency response at 20Hz/2kHz/20kHz. We must get the same signal output for the actual load
at any of the frequencies.Set the frequency at 50kHz; the output level should not decrease more than 1 or 2 dB
and there should not be any noticeable distortion.
CLIPPING AT 1kHz
Introduce such a signal that the amplifier is just about to clip.Measure the voltage up at the output (with
the actual load) and check that when the voltage decreases between 0.5 and 1 dB the clipping LEDs light down.
Check each LED corresponds to its fader.
DC OUT
For this test you must disconnect the load from the amplifier.
Introduce a 1V signal at
#
5Hz with the generator. Turn the output of the generator up untill the protection
relays open and close.
OVERHEATING PROTECTION
Disconnect the thermic sensor and shortcircuit the green and violet wires.Check that, first, the THERMAL
led of the corresponding channel is lit; second, the fan is operating at maximum speed; and third, the two
protection circuit relays are open.Connect again the connector.
Use a soldering iron to heat the thermic sensor lead and check that fan speed increases proportionally to
the sensor temperature (do not heat excessively).
Remember that each module has two sensors.
Repeat the process for the other channel.
PROTECTIONS
Disconnect the amplifier from the load and introduce with the signal generator a level of approximately
100mVRMS at 1KHz. Leave the attenuators at 0dB and shortcircuit the left channel output (just for a while)
checking the PROTECT LED is lighting up and the relay opens the circuit (you can check this by placinf an
oscilloscope probe at the amplifier's output and watching the signal disappear during the STAND BY time in which
the protection circuit is working).Repeat the same process for the right channel.
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