Table of Contents
Advertisement
1.
SCOPE
This document describes the functional test specifications for the Loewe (Beethoven) dig-
ital signal processing PCB. It is identical to the AM25/30P Series II PCB assembly test
specification 197296 except for firmware revision noted in Section 3.8, 3.9, and 3.10.
The following assembly numbers are covered;
264695-002
1.1
Mechanical Overview
This PCB assembly consists of two Digital Signal Processor PCBs on one pallet. A four
layer PCB was used to help cope with the interconnection density and to preserve signal
integrity. The DSPs, codec, and microcontroller are enclosed in a metal shield to help con-
trol EMI. (The shield covers are not installed until after board test.) R201 and R204 are not
used. They have been replaced with headers.
1.2
Electrical Overview
The PCB can accept two different types of signal inputs: a left/right analog stereo pair (sim-
ilar to AM25); and a digital bitstream capable of carrying either left/right digital PCM or
compressed Dolby Digital data.
In very general terms, signals enter the system via the ADCs or the SPDIF receiver in the
codec, subsequently, they are passed to the DSPs for processing in the digital domain,
and are passed back to the DACs in the codec for conversion back to analog. The analog
inputs (from the CD-5 or CD-20 head-end) and the analog outputs (to the amplifier PCB)
are compatible with the signal levels found on the AM-25P eq. PCB.
serial data i/o
(from CD-5)
SPDIF bitstream
(from DVD player)
line-level audio
(from CD-5)
analog
buffers
Framingham, MA 01701-9168
5v
8MHz
mC
5v
EEPROM
2
I
C
11.2896MHz
S/PDIF
3v
receiver
12v
5v-to-3v
stereo
ADC
-12v
SIZE
FSCM
A
32108
serial i/o to DSPs
3v
EPROM
3v
DSP #2
DSP #1
videostage
don. eq.
AC-3
speaker eq.
decoder
compressor
40MHz
CS4226 codec
CLASS
DWG NO.
TS
264695
uC
5VDC
EEPROM
codec
linear
buffer
3.3VDC
DSPs
smps
buffer
3v
stereo
DAC
5v
stereo
DAC
3v-to-5v
stereo
DAC
+17v
12v
-12v
analog
buffers
SHEET
REV.
36
00
2 of 16
Advertisement
Table of Contents
