Service manual

SERVICE MANUAL
IC DATA AND WAVEFORMS OF KEY POINTS
(continued)
OM8839PS/TDA884X
I
2
C-bus Controlled PAL/NTSC/SECAM TV Processors
1
. Features
The following features are available in all IC’s:
Multi-standard vision IF circuit with PLL
demodulator
Alignment-free multi-standard FM sound
demodu-lator (4.5 MHz to 6.5 MHz)
Audio switch
Flexible source selection with CVBS switch and
Y(CVBS)/C input so that a comb filter can be
applied
Integrated chrominance trap circuit
Integrated luminance delay line
Asymmetrical peaking in the luminance channel
with a (defeatable) noise coring function
Black stretching of non-standard CVBS or
luminance signals
Integrated chroma band-pass filter with
switchable centre frequency
Dynamic skin tone control circuit
Blue stretch circuit which offsets colours nea
r
white towards blue
RGB control circuit with “Continuous Cathode
Calibration” and white point adjustment
Linear RGB inputs and fast blanking
Possibility to insert a“blue back” option when no
video signal is available
Horizontal synchronization with two control loops
and alignment-free horizontal oscillator
Vertical count-down circuit
Vertical driver optimised for DC-coupled vertical
output stages
I
2
C-bus control of various functions
Low dissipation (850 mW)
2
. General Description
The various versions of the TDA 884X/5
X
series are I
2
C-bus controlled single chip T
V
processors which are intended to be applied in
PAL, NTSC, PAL/NTSC and multi-standard
television receivers.
These IC’s are nearly pin compatible with the
TDA 837× TV processors but have a highe
r
degree of integration because the delay line
(TDA4665 function) and the SECAM decode
r
have been intagrated.In addition to these
functions some additional features have been
added like “Continuous Cathode Calibration”
(2-point black current loop which results in an
accurate biasing of the 3 guns), adjustable
luminance delay time, blue stretching and
dynamic skin tone (“flesh”) control.
Functionally the IC series is split up in 3
categories, viz
Versions intended to be used in economy TV
receivers with all basic functions (envelope:
S-DIP 56 and QFP64)
Versions with additional features like E-W
geometry control, H-V zoom function and
YUV interface which are intended for TV
receivers with 110° picture tubes (envelope:
S-DIP 56)
Versions which have in addition a second
RGB input with saturation control and a
second CVBS output (envelope:QFP 64)
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