Da-15 Board - Sony PCM-1630 Operation And Maintenance Manual

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BLOCK DIAGRAM
AD-23
AD-23 BOARD
The AD-23 board converts analog signals of two channels
to digital signals, which are then outputted to the SIF-1
board. The AD-23 board features a low pass filter con-
taining a phase compensation circuit whose group delay
to 16kHz is within 10J.Lsec. This enables so called linear
phase characteristics to be obtained in practice.
The analog section consists of an input amplifier, emphasis
amplifier, dither amplifier, LPF and a headphones amplifier.
The ON/OFF switches for the EMPHASIS and DITHER
are on the AD board, and are SW1 and SW2 respectively.
When SW2 is turned ON, dither signals of each channel
synchronized to the sampling interval are generated at the
noise source circuit, and these are added to the analog
signal in the dither amplifier.
In the digital section, the timing clock from the DEC-15
board is modified to make the timing suitable for AD
conversion. In the CC control circuit, a CC clock is pro-
duced which is one BITCK ahead of WDCK 1.
In the AD conversion section, AD conversion is carried out
in accordance with the CC clock produced in the digital
section. The AD conversion section consists of AD con-
verter, oscillator, sample and hold, limiter, current source,
and AD offset feedback circuits. When the CC clock is
high level, the sample-and-hold circuit samples the input
signal, and when the CC clock goes low level, conversion
starts.
The monitor signals for headphones go to DA-15 board
through attenuators and headphones amplifiers.
8-3
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BLOCK DIAGRAM
5dBm
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INPUT
AMP
MAX
DITHER LEVEL
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A TT EMPHASIS DITHER
AMP AMP
AD-23 BOARD LEVEL DIAGRAM
8-4
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-20dB
FILTER
FILTER A/D
BUFFER CONVERTER
PCM-1630