Orban OPTIMOD-AM 9300, Operating Manual

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4-8
MAINTENANCE ORBAN MODEL 9300
D) Adjust output trim VR200 to make the meter read +10.6 dBu. (0 dBu = 0.775V
rms.) Verify a frequency reading of 400 Hz.
E) Verify THD+N reading of <0.05% (0.02% typical) using a 22 kHz low pass filter
in the distortion analyzer.
F) Set the
M
ODE to
B
YPASS
.
B
YPASS
defeats all compression, limiting, and program equalization but
retains preemphasis.
G) Verify a reading (noise) of <–80 dBu at the output of the unit.
H) Using VR201, repeat steps (C) through (G) for the Right Analog Output.
3. Check frequency response of Analog I/O.
A) Verify 9300 software controls are set to their default settings. [Refer to step
(1.A) on page 4-6.]
B) Be sure you are still in
B
YPASS mode [see step (2.F)].
C) Connect the oscillator to the Left Analog Input XLR connector.
D) Inject the Analog Input XLR connector with a level of +10 dBu with the oscilla-
tor set to 100 Hz.
E) Connect the audio analyzer to the 9300's Left Analog Output XLR connector.
F) Verify a level of +10 dBu ±1 dB. Use this level as the reference level.
G) Verify that frequency response at 50 Hz, 100 Hz, 400 Hz, 5 kHz, and 15 kHz is
within ±0.1 dB of the reference level.
This procedure tests the analog input circuitry, the A/D converter, the
DSP, the DAC, and the analog output circuitry.
H) Repeat steps (C) through (G) for the right channel.
4. Check distortion performance of Analog I/O.
A) Verify 9300 software controls are set to their default settings. (Refer to page
4-6.)
B) Be sure you are still in
B
YPASS
mode [see step (2.F)].
C) Connect a THD analyzer to the Left Analog Output #1 XLR connector. Set the
THD analyzer's bandwidth to 22 kHz.
D) Connect the oscillator to the Left Analog Input XLR connector.
E) For each frequency used to measure THD, adjust the output level of the oscil-
lator to make the
C
OMP meter on the 9300 read
100
.
F) Measure the THD+N at the frequency levels listed below.