dbx 3BX III, Руководство по обслуживанию

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Model 3BX III Service Manual
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7. PERFORMANCE TESTS
7.1 Impact-Restoration Magnitude and Timing
7.1.1 Set the controls as follows:
Expansion Minimum
Impact Restoration
Maximum
Transition Level Maximum
Pre/Post Select Pre
Source/Tape Source
Bypass
out (i.e., not set)
7.1.2 Connect the sine-wave oscillator to the tone-burst
oscillator, and connect the tone-burst oscillator output to the
left and right inputs of the 3BX III.
7.1.3 Connect the oscilloscope to the output of one channel of the
3BX III. Connect the scope sweep-trigger input to the gate or
trigger output on the tone-burst oscillator.
7.1.4 Low-Band Test
7.1.4.1 Set the oscillator to 100 Hz at 0 dBV (1 V rms) and
the tone-burst oscillator to produce approximately an 80 ms
burst (8 cycles) followed by approximately 500 ms (50 cycles)
of at least 20 dB attenuation. Set the scope to 2 V/div and
20 ms/div.
7.1.4.2 Observe the output on the scope. Verify that the wave
shape is substantially as shown in Figure 9a. Then verify for
the other channel.
Figure 9a
7.1.4.3 Observe that the Impact display lights at least 10 out
of the 12 LEDs.
7.1.5 Mid-Band Test
7.1.5.1 Set the oscillator to 1 kHz at 0 dBV (1 V rms) and the
tone-burst oscillator to produce approximately an 8 ms burst
(8 cycles) followed by approximately 100 ms (100 cycles) of at
least 20 dB attenuation. Set the scope for 2 V/div and
2 ms/div.