If you press the YES switch
on
the front panel,
the'
channel.
will be assigned to mixer Group
A.
If you press the NO switch
on
the (
front panel, the channel is assigned
to
mixer Group
B.
4.14 - CHANNEL AND AMPLITUDE DAC TEST
1. Select the CHANNEL TEST
2.
Select AUDIO OUTPUT MUTED
3.
Select C2 SINEWAVE at 5kHz SAMPLING RATE
4.
Enable channels 1 through
12,
ramp amplitude DACs, Group A
5.
Use
an
oscilloscope and probe the test points indicated
in
Table 2 or 3 to verify channel operation. Probe the test
points
indicated
in Table 4 to
verify
Amplitude DAC
operation.
NOTE:
Use
caution
when
probing
pin
7
of
the
amp
DAC
opamps,
because
pin
8
is
a
power
pin.
If
the
scope
probe
shorts
pin
7
to
pin
8
the
opamp
will
be damaged.
The frequency of the sinewave
will vary depending upon the
sampling rate selected. Table 1 shows the 12 possible frequencies
available. The time
(T)
shown
in
Table 1 indicates the period of each
sinewave. Figure 1 shows how the sinewave should appear at the
outputs of the
aUas
filters (See Table 2).
TABLE
1:
SINEWAVE
PERIOD
TIMES
(T)
SAMPLI
NG
RATE
C2 C5
5kHz
15
ms
3.8
ms
10kHz
7.5
ms
1.9
ms
15kHz
5.0
ms
1.25
ms
25kHz
3.0
ms
0.75
ms
Kurzwell 250 Service Manual, Chapter 4
4 -
26
C8
0.7
ms
.35
ms
0.25
ms
0.15
ms
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