dbx 3BX III, Service Manual

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Model 3BX III Service Manual
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Figure 10c
7.2.5.3 Observe that the high-band display lights at least to
the 5
th
red LED during the burst and returns to the 1
st
red LED
between bursts.
7.3 Expansion Tracking
7.3.1 Set the unit as in 7.2.1
7.3.2 Connect the sine-wave oscillator to the left and right inputs
of the unit.
7.3.3 Connect the output of one channel to an AC voltmeter.
Figure 10b
7.2.4.3 Observe that the mid-band display lights at least to
the 4
th
red LED during the burst and returns to the 1
st
red LED
between bursts.
7.2.5 High-Band Test
7.2.5.1 Set the sine-wave oscillator and the tone-burst
generator as in 7.1.6.1. As in the low-band test, the 20 dB
figure is critical to achieving results consistent with the
pictures presented here. Set the scope to 2 V/div and
2 ms/div.
7.2.5.2 Observe the output on the scope. Verify that the wave
shape is substantially as shown in Fig. 10c, and then confirm
for the other channel.