Daewoo DTX-21B4, Service Manual

CP-520

V

 Service Manual 

20

4.1.4 

FEATURES 

 
Analogue Video Processing (all versions) 

·   Multi-standard vision IF circuit with alignment-free PLL demodulator 
·   Internal (switchable) time-constant for the IF-AGC circuit 
·   Switchable group delay correction and sound trap (with switchable centre frequency) for the 
demodulated CVBS signal 
·   DVB/VSB IF circuit for preprocessing of digital TV signals. 
·   Video switch with 3 external CVBS inputs and a CVBS output. All CVBS inputs can be used as 
Y-input for Y/C signals. However, only 2 Y/C sources can be selected because the circuit has 2 
chroma inputs. It is possible to add an additional CVBS(Y)/C input (CVBS/YX and CX) when the 
YUV interface and the RGB/YPRPB input are not needed. 
·   Automatic Y/C signal detector 
·   Adaptive digital (4H/2H) PAL/NTSC comb filter for optimum separation of the luminance and the 
chrominance signal. 
·   Integrated luminance delay line with adjustable delay time 
·   Picture improvement features with peaking (with switchable centre frequency, depeaking, 
variable positive/negative peak ratio, variable pre-/overshoot ratio and video dependent coring), 
dynamic skin tone control, gamma control and blue- and black stretching. All features are 
available for CVBS, Y/C and RGB/YPBPR signals. 
·   Switchable DC transfer ratio for the luminance signal 
·   Only one reference (24.576 MHz) crystal required for the TCG m-Controller, digital sound 
processor, Teletext and the colour decoder 
·   Multi-standard colour decoder with automatic search system and various “forced mode” 
possibilities 
·   Internal base-band delay line 
·   Indication of the Signal-to-Noise ratio of the incoming CVBS signal 
·   Linear RGB/YPBPR input with fast insertion. 
·   YUV interface. When this feature is not required some pins can be used as additional 
RGB/YPBPR input. It is also possible to use these pins for additional CVBS (or Y/C) input 
(CVBS/YX and CX). 
·   Tint control for external RGB/YPBPR signals 
·   Scan Velocity Modulation output. The SVM circuit is active for all the incoming CVBS, Y/C and 
RGB/YPBPR signals. The SVM function can also be used during the display of teletext pages. 
·   RGB control circuit with ‘Continuous Cathode Calibration’, white point and black level off-set 
adjustment so that the colour temperature of the dark and the light parts of the screen can be 
chosen independently. 
·   Contrast reduction possibility during mixed-mode of OSD and Text signals 
·   Adjustable ‘wide blanking’ of the RGB outputs 
·   Horizontal synchronization with two control loops and alignment-free horizontal oscillator 
·   Vertical count-down circuit 
·   Vertical driver optimized for DC-coupled vertical output stages 
·   Horizontal and vertical geometry processing with horizontal parallelogram and bow correction 
and horizontal and vertical zoom 
·   Low-power start-up of the horizontal drive circuit 

Analogue video processing (stereo versions) 

·   The low-pass filtered ‘mixed down’ I signal is available via a single ended or balanced output 
stage. 

Analogue video processing (mono versions) 

·   The low-pass filtered ‘mixed down’ I signal is available via a single ended output stage 

Digital Video Processing (some versions) 

·   Double Window mode applications. It is possible to display a video and a text window or 2 text