Orban OPTIMOD 6300 Operating Manual page 240

4-8
MAINTENANCE
g) Navigate to S
the N and P
EXT
PRE-E...................................................................................................Flat
AGC PRE-E ..........................................................................................Flat
MB PRE-E ............................................................................................Flat
2. Test the power supply
The power supply is a module. In case of any power supply failure, the entire
supply must be replaced by an exact replacement (available from Orban Service).
Attempts to repair the supply on a component level and/or to replace the supply
with a non-approved supply may compromise your Optimod's compliance with
the EMI and safety regulations in your country.
The +3.3V and +2.5V supplies are locally regulated on the DSP and con-
trol boards (see Section 6).
Measure the power supply's regulated voltages at the DVM and observe the rip-
ple with an oscilloscope, AC-coupled. Convenient sources of these voltages are
the inductors adjacent to power supply connectors on the I/O+DSP board. Con-
nect your probe to the sides of the inductors away from the power supply con-
nectors. The results in Table 4-1 are typical.
Power Supply Rail
+15VDC
–15VDC
+5VDC
Table 4-1: Typical Power Supply Voltages and AC Ripple
3. Adjust Analog Output Level Trim.
A) Verify 6300 software controls are set to their default settings. [Refer to step
(1.A) on page 4-7.]
B) Feed the 6300 output with the built-in 400 Hz test tone:
a) Navigate to S
b) Set the M
ODE
C) Connect the audio voltmeter to the Left Analog Output.
D) Adjust output trim VR200 to make the meter read +10.0 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 to B
ODE
B
defeats all compression, limiting, and program equalization but
YPASS
retains preemphasis.
G) Verify a reading (noise) of <–80 dBu at the output of the unit.
ETUP and set controls as follows. Scroll the display by using
REV buttons access the following controls:
DC Voltage (volts)
+15  0.5
–15  0.5
+5  0.25
> T
ETUP EST .
to T
ONE .
.
YPASS
ORBAN MODEL 6300
AC Ripple (mV p-p)
<20
<20
<20