Optimod-Surround 8685 V1.0 Operating Manual - Orban

OPTIMOD SURROUND PROCESSOR TECHNICAL DATA 6-9
field-repairable.
2. Color LCD Display
The color LCD is an active-matrix quarter-VGA panel. The CPU addresses its controller
chip through the CPU’s ISA bus. The controller is on a board sandwiched between
the CPU module and the base board: The graphics controller plugs into the base
board and the CPU module plugs into the graphics controller.
The backlight on the display has a finite lifetime (normally a few years of continuous
operation). Therefore, the 8685 always implements a screen-saver timeout. This is
not user-adjustable.
Input Circuits
This circuitry interfaces the digital inputs to the DSP. The digital input receivers accepts
AES3-format digital audio signals from the digital input connector and sample
rate-converts them as necessary. The digital audio from the A/D and SRC is transmitted
to the DSP.
1. Digital Input Receiver and Sample Rate Converter (SRC)
Located on Input/output board
The digital input receivers IC301A, 302A, 303A, 401A, 402A accept digital audio
signals using the AES3id interface format (AES3-1992). They apply their outputs
to sample rate converters IC304B, 305B, 306B. These accept and sample-rate convert
any of the “standard” 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz rates
in addition to any digital audio sample rate within the range of 32 kHz and 96
kHz. The SRC converts the input sample rate to 48 kHz for processing by the DSP.
Receiver IC403A accepts sync signals in AES3id or AES11id format from J403A.
The signal at J403A is also applied to word clock receiver/PLL receiver IC501. Either
IC403A or IC501 generates a reference sample rate for the 8685’s output
sample rate converters.
These chips are surface-mounted and not field-replaceable without surfacemount
rework equipment.
SDI Option:
The digital input receivers for the AES3id inputs are U300A, U302A, and U304A.
The associated sample rate converters are U301B, U303B, and U305B.
The sample rate converters for SDI audio input channels 1/2, 3/4, 5/6, and 7/8 are
U400A, U400B, U401A, and U401B respectively.