Orban OPTIMOD-FM 8600Si, Operating Manual

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OPTIMOD-FM DIGITAL MAINTENANCE
4-7
the more severe faults that could develop in the 8600Si circuitry even in high-RF en-
vironments.
See the assembly drawings in Section 6 for component locations.
Be sure to disconnect the AC line cord before removing or installing circuit boards.
Follow these instructions in order without skipping steps.
Note: To obtain an unbalanced output, jumper pin 1 (ground) to pin 3, and measure
between pin 1 (ground) and pin 2 (hot).
Note: All analog output measurements are taken with a load resistance of 10K or
higher, corresponding to the modern practice of terminating analog lines with a
bridging load.
1. 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, +1.2V, and +2.5V supplies are locally regulated on the DSP and
control 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 DC Voltage (volts) AC Ripple (mV p-p)
+15VDC
+15
±
0.5
<20
–15VDC
–15
±
0.5
<20
+5VDC
+5
±
0.25
<20
Table 4-1: Typical Power Supply Voltages and AC Ripple
2. Prepare the unit for audio measurements.
A) Use the front panel controls to set the 8600Si's software controls to their de-
fault settings as follows:
a) Navigate to
Setup
> I/O C
ALIB
> A
NLG
I
N
C
ALIB
. After writing down the old
settings (so you can restore them later) or saving them via PC Remote, set
controls as follows:
INPUT ............................................................................................ analog
AI Ref VU ..................................................................................... 0.0 dBu
R CH BAL.........................................................................................0.0 dB