Scope Photos - Bose Loewe Concertos Acoustimass 61247 Service Manual

Scope Photos

The bass module is muted when it is first powered up and will not un-mute until it receives an
"un-mute" or "volume up" command.
Muted data consists of all zeroes; this condition is shown in the lower trace of the codec (U100)
scope photo, mute condition.
Upper trace: LR_CLK (U100 pin 37) 44.1 kHz square wave
Middle trace: SDOUT1 (U100 pin 36) serial data out
Lower trace: SDIN1 (U100 pin 34) serial data in
Figure 9. Codec (U100) Scope Photo, Mute Condition
The significance of the SDOUT1 signal (U100 pin 36) is that it represents the digital audio data at
the start of the digital audio signal path. This data is transmitted serially to the DSP1, which re-
quires three signals to accept it:
SCLK (U100 pin 38): to clock the serial data in
LRCLK (U100 pin 37): to indicate the start of each audio sample
SDOUT1 (U100 pin 36): the serial audio data
The significance of the SDIN1 signal (U100 pin 34) is that it represents the output of the digital
audio signal chain. The data is shifted out from DSP2 using the clock signals mentioned above.
If this signal is dead, DSP2 is most likely not running. See Figure 44.
20