Orban OPTIMOD-FM 8600, Operating Manual

Page: 294 / 397

4-10
MAINTENANCE ORBAN MODEL 8600
Number of Red Flashes Problem With
7 DSP B +3.3V supply
8 CPU +3.3V supply
9 CPU +2.5V supply
Table 4-1: Decoder Chart for Power Supervisor
You can monitor power supply voltages at connector J7 on the power
supply board (see page 6-51 for the parts locator drawing and page 6-52
for the schematic). When one faces the connector, the voltages can be
found on the pins in the following pattern:
(1) + unreg. (3) digital gnd (5) +15V (7) +5 V digital (9) –5V analog
(2) - unreg (4) chassis gnd (6) -15V (8) +5V analog (10) NC
Table 4-2: Layout Diagram of J7, with expected voltages on each pin
C) Measure the regulated voltages at J7 with the DVM and observe the ripple
with an oscilloscope, AC-coupled. The following results are typical:
Power Supply Rail DC Voltage (volts) AC Ripple (mV p-p)
+15VDC
+15
±
0.5
<20
–15VDC
–15
±
0.5
<20
+5VDC
+5
±
0.25
<20
–5VDC
–5
±
0.25
<20
D5VDC
+5
±
0.25
[Obscured by noise]
Table 4-3: Typical Power Supply Voltages and AC Ripple
3. Check Analog Output Trim Levels.
A) Verify 8600 software controls are set to their default settings. (Refer to page
4-8.)
B) Feed the 8600 output with the built-in 400 Hz Test tone.
To turn on the
T
EST
tone:
a) Navigate to System Setup.
b) Choose Test Modes.
c) Navigate to the Tone button and press Enter.
C) Connect the audio voltmeter to the Left Analog Output.
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) Recall the bypass preset: Navigate to the
B
YPASS
button and press
E
NTER
.
Bypass defeats all compression, limiting, and program equalization but
retains preemphasis.
G) Verify a reading (noise) of <–80 dBu at the output of the unit.