Lexicon RV-8 Service Manual page 119

Lexicon
Video Board Connector (J29)
J29 is a 16 position FFC connector that conveys all the signals necessary for Host CPU access to the on-
board FPGA and the Video Decoder/Encoder components.
VIDEO_RESET/ is a buffered equivalent of the active low reset signal generated by U31. It provides an
initiating signal to the state machines within the FPGA on the Video Board.
SYNC_DETECT is a signal that indicates the presence or absence of video synchronization from the
Video Board.
OSD_CS/ is the chip select for the Fujitsu MB90092 OSD Controller device located on the Video Board.
VIDEO_SCLK is the serial data shift clock that comprises the SPI interface to the OSD and control logic.
VIDEO_DATA is the serial data that is part of the SPI interface to the Video Board.
VIDEO_REG comprise the remainder of the SPI interface to the On-Screen Display controller and the
video board control logic.
2
VID_I2C_SDATA is a serial data stream that communicates to the Video Codec using I C protocol.
P
P
2
Provision is made for a pull-up resistor R180 for compliance with the I C specification. The equivalent
P
P
resistor is already populated on the Video Board, and hence is not needed here.
2
VID_I2C_SCLK is the serial data stream shift clock that communicates to the Video Codec using I C
P
P
2
protocol. Provision is made for a pull-up resistor R181 for compliance with the I C specification. The
P
P
equivalent resistor is already populated on the Video Board, and hence is not needed here.
CVID_ZON3 is a composite video analog signal that is sourced from a video selector that selects
between one of five composite inputs or one of five S-VIDEO inputs on the rear panel.
Amp Power Supply Connector (J27)
J27 is a 6 position FFC connector that provides enable controls for the Amplifier Power Supply Board
Relays that activate the power amplifiers. This connector also provides a BROWN_OUT signal to the
Host CPU, where it is monitored as a Non-Maskable Interrupt (NMI). Provision is made to use
conventional ribbon cable for board interconnect via J28, but to date is not used in this design.
SOFT_RLY is a signal that is activated from the external registers on sheet 2. This signal enables a
current limited supply voltage to the power amplifiers during the final stages of boot-up. During this phase
of the boot process, readiness status is queried of each of the amp channels by the Host. This relay
signal returns to the inactive state if a problem is found within the amplifier blocks, and also when the
power supply has stabilized and current limiting on the supply rails is no longer necessary.
MAINS_RLY is a signal that is also activated from the external registers on sheet 2. This signal enables
the full supply to the amplifiers once the state of the amplifier channels are known to be good. This relay
activates before the SOFT_RLY signal is made inactive.
BROWN_OUT is a monitoring signal from the amp power supply that will trigger an NMI if the power
supply rails drop by more than 10% of their nominal voltage. This will place the RV-8 into a standby mode
with the amplifiers shut off until the supplies have stabilized.
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