Daewoo DV-K882SY-AN, Руководство по обслуживанию

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3-4. AUDIO CIRCUIT OPERATION
1. Signal flow of Normal audio in REC mode.
The recording audio signals from IF circuit are input to the inputselector through pin 2 (left), 3 (right) of the IC201 and the
input signal are selected.
This audio AMP circuit amplifies input audio signal by about 4DB and then the signals are mixed. The AGC circuit is used
to keep the amplitude of audio signal constant. The signal from the AGC circuit is input to the REC EQ circuit through
buffer. This REC EQ circuit amplifies input audio signal by about 12DB. This signal from REC EQ circuit outputs to the pin
33 of IC201, and then the signal is recorded on tape with external AC bias to the audio head.
2. Signal flow of Normal audio in PB mode.
The audio signal from audio head to pin 34 of IC201 is fed to the PB EQ circuit.
Time constant of PB EQ circuit is controlled by I2C BUS with control byte.
Output selector circuit separates the audio signal from mute circuit into two audio signals and then the audio signals
output to pin 21 (left) and pin 22 (right) separately.
we designed that the amplitude of the output signals is –6dBm.
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Input Selector
Volume L
Audio
AGC
@
#
Volume R
+
E
REC
EQ
T
W e R
Audio input
LEFT
RIGHT
AMP 4dB
To A.HEAD
Buffer
t
PB
EQ
y Y
A.MUTE
Output
Selector
Line
Selector
“
‘
LP
Buffer
LEFT
RIGHT
Audio Output
LEFT
RIGHT
Audio input
BLOCK A-1. Normal audio signal flow in the REC mode.
BLOCK A-2. Normal audio signal flow in the PB mode.