dbx 3BX III, Руководство по обслуживанию

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Model 3BX III Service Manual
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4.1.2 Connect the sine-wave oscillator to both inputs of the unit
under test. Set it to 20 Hz and an output level of +10 dBV
(3.16 V). Connect the scope to the output of the low-band rms-
detector buffer at TP10 (U710, pin 7) and set it to 2 mV/div (AC-
coupled) and 10 ms/div.
4.1.3 Adjust VR704 for best rms symmetry, as shown in Fig. 7a.
4.1.4 Reset the oscillator to 100 Hz, +10 dBV (3.16 V).
4.1.5 Also connect a digital voltmeter to TP10.
4.1.6 Adjust VR705 for 0.00 Vdc ±10 mV. Verify that no more than
one LED in the low-band gain-change display is lit.
4.1.7 Reduce the oscillator’s output level in 10 dB steps and
verify that the voltage at TP10 changes as follows:
Input Level TP10 Voltage Tolerance
+10 dBV 000 mV dc ±10 mV
0 dBV +541 mV dc ±50 mV
-10 dBV +1080 mV dc ±100 mV
-20 dBV +1620 mV dc ±150 mV
Figures 7a 7b 7c
Wrong:
Right: