Bose AV28 - Page 17

17
Theory of Operation
The AV28 Signal Routing and Clocking Diagram, which follows, shows the fully-detailed audio
path, including clocking information. The legend at the bottom identifies which signals are analog,
which are digital, and what the relevant clock rates/sources are.
AV28 AUDIO PATH:
Signal Routing and Clocking
U1
S/PDIF
SOURCES
U304
74HC157
MUX
74HC157
MUX
U402
ZONE 1 OUT
ZONE 2 OUT
AUX EXT
OPTICAL EXT
TAPE EXT
VCR EXT
TV EXT
U501
0
1
2
3
4
5
6
OUT
CS8415
S/PDIF
MUX
AND
RCVR
OPTICAL
S/PDIF
RCVR
J501
ANALOG L/R
I
2
S: U303 PROVIDES CLOCK (ALWAYS 44.1 kSPS)
I
2
S: U1 OR U501 PROVIDES CLOCK (SOURCE DEPENDENT)
I
2
S: U303, U1 OR U501 PROVIDES CLOCK
S/PDIF: UP TO 96 kSPS
CS8405
S/PDIF
XMTR
U406
74HC157
MUX
U404
ZONE 2
S/PDIF
DIGITAL
OUTPUT
J701
OPTICAL
S/PDIF
DRIVER
S/PDIF
RECORD
OUTPUT
OPTICAL
S/PDIF
RECORD
OUTPUT
VCR EXT
AUX EXT
TAPE EXT
TUNER
DVD MIXDOWN
TV EXT
U201
TEA6422
ANALOG
MUX
1
2
3
4
5
6
1
2
3
ANALOG
L/R
SOURCES
CS4340
DAC
D/A
U503
D/A
CS4340
DAC
U202
U306
CS8405
S/PDIF
XMTR
U302
74HC157
MUX
U303
ZONE 2
ANALOG
L/R
VARIABLE
OUTPUT
ZONE 1
ANALOG
L/R
VARIABLE
OUTPUT
ANALOG
L/R
RECORD
OUTPUT
ZONE 1
S/PDIF
DIGITAL
OUTPUT
ANALOG
HEADPHONE
OUTPUT
NJM4556
BUFFER
U205
U1
CS98K
(LS500C)
DVD
DECODER
AC-97 PORT
(CONFIGURED AS I2S)
I2S
AUDIO
PORT
D0
D1
D2
D3
IN
ATAPI
XFACE
DVD ROM
74HC157
MUX
U502
74HC157
MUX
U505
CS4224
CODEC
A/D
VOLUME
CELL
D/A
U403
A/D
D/A
VOLUME
CELL
CS4224
CODEC
Port supports many sample
rates (but D0-D3 and IN
always share the same rate).
Port must always
run at 44.1kHz
sample rate
(clocked by U303).