Nexo NXAMP 4X4, Service Manual

Page: 80 / 153

4-1. Link out
Input the 1 kHz, -10 dBu sine wave to each input terminal and confirm that the output voltage obtained at each link out
terminal is -10 ±0.5 dBu.
4-2. Efficiency
Input the 1 kHz sine wave to the channel 1 input terminal and confirm that the primary power consumption is 500 ±30 W
when the output voltage obtained at the channel 1 output terminal is +34.7 dBu.
Perform the same test for channels 2-4 in the same manner.
4-3. Gain
Input the 1 kHz, 0 dBu sine wave to each input terminal and confirm that the output voltage obtained at each output
terminal is +34.1 ±1.2 dBu.
4-4. Frequency response
Perform the following test at each channel.
Input the 10 Hz, 1 kHz, 20 kHz, 0 dBu sine wave to the input terminal and one by one measure the output voltage obtained
at the output terminal for each frequency.
Confirm that the output voltage at 10 Hz is 0 ±0.5 dB when compared with the output voltage at 1 kHz (0 dB).
Confirm that the output voltage at 20 kHz is +0.5 ±0.5 dB when compared with the output voltage at 1 kHz (0 dB).
4-5. Distortion
1) Input the 1 kHz sine wave to the channel 1 and channel 2 input terminals and confirm that the distortion at the channel
1 and channel 2 output terminals is 1.0 % or less when 1800 W (with 8 Ω load) output is obtained for each terminal at
the same time.
2) Input the 1kHz sine wave to the channel 3 and channel 4 input terminals and confirm that the distortion at the channel
3 and channel 4 output terminals is 1.0 % or less when 1800 W (with 8 Ω load) output is obtained for each terminal at
the same time.
4-6. Maximum output
Perform the following test at each channel one by one.
Connect the 4 Ω 500 W resistor to output terminal.
Input the BURST signal as shown in fig. 2 to input terminal and adjust the input signal level so that a Vburst voltage of 317
Vp-p (volt peak to peak) is obtained at output terminal.
Measure the last wave of the BURST signal peak to peak by the oscilloscope’s MEASURE function. Confirm that the
measured voltage is 310 volt or more. (See fig. 2)
Fig. 2
The last one wave of burst signal
shall be measured.
Close-up
The center of the emission line shall
be adopted as the measurement value.
Signal
20 msec
1 msec
500 msec
Vburst
Cursor
NXAMP4x4
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