User's Manual

Model 1150A DVOR
2-50 Rev. - November, 2008
This document contains proprietary information and such information may not be disclosed
to others for any purposes without written permission from SELEX Sistemi Integrati Inc.
Analog buffer U8:A sends a single-ended test generator waveform to A-D converter U14 for on-board testing and
verification. The U14 A-D converter is serially controlled by signals SPI_SCK, SPI_MISO, and ~SPI_CS3X of the
RMS CCA via connector P2. The U14 D-A converter has a built-in +2.5VDC reference which is filtered by
capacitors C41 and C42, buffered by amplifier U21:A, and presented to the U12 Audio D-A converter.
The audio source is either microphone input MIC+_IN from connector J1 or transformer T2. Transformer T2, which
is driven from the Control Backplane voice terminal block via connector P1, is disconnected when a microphone is
plugged into connector J1.
Parallel data, address, and control (D0X, A1X, and ~AOEX for example) from the RMS CCA enter via connector
P2, are buffered by U16 and U17, and decoded by the U1 PLD to determine the ~EXT signal. The ~EXT signal
controls the U17 bus buffer data direction.
Audio output to connector J2 originates at the Monitor CCAs, enters as SPKR+ and SPKR- through connector P1,
and arrives at headphone connector J2. If a headphone or speaker is not plugged into J2, audio output couples
through transformer T1 as SPKR_XFMR+ and SPKR_XFMR-. These signals exit connector P1 and eventually
terminate at the Voice terminal block on the Control Backplane.
2.3.2.16
Low Voltage Power Supply (1A3A4, 1A3A8) CCA Theory
There are two LVPS assemblies used on the transmitter cabinet. The low voltage power supply CCA. LVPS 1A3A4
is the low voltage power supply for transmitter 1 and 1A3A8 is the LVPS for transmitter 2. Each LVPS is identical
in construction and operation. Each is interchangeable with the other.
2.3.2.16.1
Low Voltage Power Supply (LVPS) CCA Block Diagram Theory
Refer to Figure 2-19. The LVPS CCA converts +48VDC system power to +28VDC, +5VDC, +12VDC, and -
12VDC for eventual use by the Synthesizer, Monitor, and Audio Generator CCAs.
The +48V from connector P2 is fused and feeds two DC-DC converters. One DC-DC converter creates +28VDC
while the other generates +5VDC, +12VDC, and -12VDC.
Each of the aforementioned output voltages is range-monitored by window comparators. The wired-OR’d outputs of
the window comparators assert a power-OK signal and light an LED when all output voltages are within the
tolerance windows. The power-OK signal eventually routes to the Facilities CCA for PMDT reporting.
The ~TEST signal when asserted from the LCU via connector P2 will insure the power-OK LED is lighted no
matter the output of the window comparators.
The VCO_EN signal from the LCU via connector P2 is filtered and routed out to connector P2 and eventually the
Synthesizer CCA as signal VCO_PWR.