Alto DPA 2500, Руководство по обслуживанию

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1. If the panel shows”56”, the Connection is ok.
2. Done.
PCB Test
Instruments
1. DMM
2. Audio Analyzer unit
3. Oscillograph
4. 8 Ω (400W) load
1) Test procedures and specification
1.Set LIMITER and BRIDGE switches in the position OFF. Turn VR of CH1 and CH2 to
maximum, then turn on the power switch and the blue power LED lights up, and
OPERATING/PROTECTION LED shows red, then it turns green after 2-5 seconds or so.
a. Without signal input, adjust R1-16(CH1) and R2-16(CH2) so that the voltage of R1-17/2-17 is
132
±
2Mv. Connect a 4
Ω
load at output. Input a 5KHz –3/-0.5dB signal into CH1 or CH2
(output 2V). Verify the curve on oscilloscope and there should be no crossover distortion, then
the oscillograph shows curve distortion should be 2-3%. Adjust the R1-20, R1-21 (CH1); R2-20,
R2-21 (CH2) make sure that the crossover distortion reaches its peak. (NOTE: maintain the
power is 230V).
b. Set the output is short circuit, then adjust the LED for the LIMITER on the panel will be
illuminated and the power consumption of the short circuit protection should be less than 485W.
c. S/N: more than 88dB (A weighted is more than 100dB).
d. Compressor function test: Turn on LIMITER switch. Input a 1KHz / +10dB signal, the
LIMITER LED is lit yellow and there is no clipped signal.
e. Adjust the VR on front panel so that the output is :2V(4
Ω
). The measured frequency
response is more than 28Hz to 20 kHz+/-1dB (CH1/CH2)
f. The output is more than 59V.
i. Release the BRIDGE switch. Input a 1KHz signal into CH1(the level control of CH2 is turn to
minimum). Connect a 8
Ω
load with output terminal. Measure the bridged output voltage is