Orban Optimod-FM 8300 Operating Manual page 197

OPTIMOD-FM DIGITAL
It is often more convenient to make measurements on the bench away from high RF
fields which could affect results. For example, in a high RF field it is very difficult to
accurately measure the very low THD produced by a properly operating 8300 at
most frequencies. However, in an emergency it is usually possible to detect many of
the more severe faults that could develop in the 8300 circuitry even in high-RF envi-
ronments.
See the assembly drawings in Section 6 for component locations.
Be sure to turn the power off 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 620 ±5% resistor tied be-
tween pin 2 and 3 of the XLR connector.
1. Prepare the unit.
A) Set the GND LIFT switch to the earth ground symbol setting (left position) to
connect chassis ground to circuit ground.
B) Use the front panel controls to set the 8300's software controls to their de-
fault settings, as follows:
a) Navigate to S
settings (so you can restore them later), set controls as follows:
Input ............................................................................................. analog
AI Ref VU ................................................................................... +4.0 dBu
R CH BAL.........................................................................................0.0 dB
b) Navigate to S
DI Ref VU ................................................................................ –15.0 dBFS
R CH BAL.........................................................................................0.0 dB
c) Navigate to Setup / Io Calib / Anlg Out Calib. Set controls as follows:
AO 100% ................................................................................. +10.0 dBu
AO Pre-E .............................................................................................Flat
AO FEEDS......................................................................................xmitter
d) Navigate to S
DO 100% .................................................................................. –2.8 dBFS
DO Pre-E ............................................................................................. flat
DO RATE ........................................................................................32 kHz
DO SYNC......................................................................................internal
e) Press the N
/ I C / A
ETUP O ALIB
/ I C / D
ETUP O ALIB IG
/ I C / D
ETUP O ALIB IG
button. Set controls as follows:
EXT
I C . After writing down the old
NLG N ALIB
. Set controls as follows:
I C
N ALIB
O C . Set controls as follows:
UT ALIB
4-7
MAINTENANCE