akira CT-14CQS5CPT, Service Manual

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Model no.:CT-21CQS5CPT.doc
version 1.0
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SERVICE DATA
1 TV signal processor TDA935X/8X PS-N3 series
1.1 GENERAL DESCRIPTION
The various versions of the TDA935X/8X/ PS-N3 series combine the functions of a video
processor together with a -Controller and US Closed Caption decoder. Most versions have
a Teletext decoder on board. The Teletext decoder has an internal RAM memory for 1 or 10
page text. The ICs are intended to be used in economy television receivers with 90and 1
10picture tubes. The ICs have supply voltages of 8 V and 3.3 V and they are mounted in an
SDIP-64 envelope.
The features are given in the following feature list.
1.2 FEATURES TV processor
Available in TDA935X/6X/8X PS versions
·Multi-standard vision IF circuit with alignment-free PLL demodulator
·Internal (switchable) time-constant for the IF-AGC circuit
·The mono intercarrier sound circuit has a selective FM-PLL demodulator which can be
switched to the different FM sound frequencies (4.5/5.5/6.0/6.5 MHz). The quality of this
system is such that the external band-pass filters can be omitted.
·The FM-PLL demodulator can be set to centre frequencies of 4.74/5.74 MHz so that a
second sound channel can be demodulated. In such an application it is necessary that an
external band pass filter is inserted.
·Integrated chrominance trap circuit
·Integrated luminance delay line with adjustable delay time
·Picture improvement features with peaking (with switchable centre frequency, depeaking,
variable positive/negative overshoot ratio and video dependent coring) and blue- and black
stretching. All features are available for CVBS, Y/C and YPBPR signals.
·Tint control for external RGB/YPBPR signals
·Integrated chroma band-pass filter with switchable centre frequency
·Only one reference (12 MHz) crystal required for the -Controller, Teletext- and the colour
decoder
·Multi-standard colour decoder with automatic search system
·Internal base-band delay line
·Indication of the Signal-to-Noise ratio of the incoming CVBS signal
·A linear RGB/YUV/YPBPR input with fast blanking for external RGB/YUV sources. The
synchronisation circuit can be connected to the incoming Y signal. The Text/OSD signals
are internally supplied from the -Controller/Teletext decoder.
·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.
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levels of contrast reduction of main picture possible during OSD/Text insertion (‘halftone’)
·OSD/Text gain reduction control
·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