OPTIMOD-FM TECHNICAL DATA
6-13
The power supply circuits are straightforward and no explanation is required beyond the
schematic itself. Be aware that C19, C50, C52, and C53 in the switching regulator are
premium-quality low-ESR capacitors and must be replaced with equivalent types to en-
sure proper operation of the switching supply.
The output of the power supply is monitored by the power-indicator LED circuit, which
causes the power LED to flash according to a preset code to diagnose problems with the
various power supplies in the 8400. See step (2.B) on page 4-10.
Abbreviations
Some of the abbreviations used in this manual may not be familiar to all readers:
A/D (or A to D) analog-to-digital converter
AES Audio Engineering Society
AGC automatic gain control
A-I analog input
A-O analog output
BAL balanced (refers to an audio connection with two active conductors and one shield sur-
rounding them).
BBC British Broadcasting Corporation
BNC a type of RF connector
CALIB calibrate
CIT composite isolation transformer
CMOS complementary metal-oxide semiconductor
COM serial data communications port
D/A (or D to A) digital-to-analog converter
dBm decibel power measurement. 0 dBm = 1mW applied to a specified load. In audio, the load
is usually 600Ω. In this case only, 0 dBm = 0.775V rms.
dBu decibel voltage measurement. 0 dBu = 0.775V RMS. For this application, the dBm-into-
600Ω scale on voltmeters can be read as if it were calibrated in dBu.
DI digital input
DJ disk jockey, an announcer who plays records in a club or on the air
DO digital output
DOS Microsoft disk operating system for IBM PC
DSP digital signal processor (or processing). May also refer to a special type of microprocessor
optimized for efficiently executing arithmetic.
EBU European Broadcasting Union
EBS Emergency Broadcasting System (U.S.A.)
EMI electromagnetic interference
ESC escape
FCC Federal Communications Commission (USA regulatory agency)
FDNR
frequency-dependent negative resistor⎯an element used in RC-active filters
FET field effect transistor
FFT fast Fourier transform
FIFO first-in, first-out
G/R gain reduction
HF high-frequency
HP high-pass
IC integrated circuit
IM intermodulation (or “intermodulation distortion”)
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