Daewoo DV-K82 series, Service Manual

Page: 12 / 129

10 CIRCUIT
2. PLAYBACK PROCESSING
PLAYBACK ENVELOPE signal from the PRE-AMP IC is supplied to the 15th pin of A/V IC for processing the PAL
color, luminance respectively.
The output signal through Y/C MIX after each processing of chrominance and luminance is supplied to the 18th pin
of OSD IC.
1) LUMINANCE SIGNAL PROCESSING (PB)
The PLAYBACK ENVELOPE signal is equalized by the PB-EQ, which flattens the whole frequency characteristic.
And the PB-EQ is determined by the GROUP , MSB 7-8 bits.
Phase compensation part improves the pulse characteristics.
DOUBLE LIMITER restores the high frequency portion, and eliminates the spike noise, and AM components.
The signal through DOUBLE LIMITER is then demodulate, and then the RECORD NONLINEAR EMPHASIS
characteristic is compensated by the DE-EMPHASIS.
Double High Pass Noise Canceller eliminates the high frequency noise against PB signal.
The Picture Control circuit improves the picture sharpness, while its characteristic is determined by the GROUP 8,
LSB 1-4 bits.
15
25
5 42 7 40
26
17 20 PB-EQ PHASE COMP
DOUBLE LIMITER SUB-LPF
CLAMP LPF YNR N.L. DE-EM DHP NC
FM DEMOD
PIC CTL Y/C MIX
Y/C MIX
(LC89977M)
CLAMP
FM AGC
PRE-AMP 7th PIN
FIG.5 Luminance Signal Processing (PB)
PB ENVE
PRE-AMP
7th PIN
35
38 Y/C MIX FBC VIDEO AMP
luminance signal
processing
chrominance signal
processing
OSD IC 18th PIN
FIG.4 Playback Processing