Daewoo Dtf 2950 Service Manual

							CP-850FX Service Manual 
 
Europe R&D 
50 pixels by subsampling. To prevent the introduction of alias distortion low pass filters are used for 
luminance and chrominance processing. The horizontal prescaler consists of two main 
subsampling stages. The first stage is a scaler for rational decimation factors in a range of 1 to 2. 
The second stage decimates in integer steps (1,2,3,4...32). 
 
5.3.1.8.2 Noise Reduction 
The structure of the temporal motion adaptive noise reduction is the same for luminance as for 
chrominance signal. 
The output of the motion detector is weighted. The look-up table input value range is separated 
into 8 segments. It is possible to freely program different behaviour of the noise reduction by 
using predefined curve characteristic for each segment.  
 
5.3.1.8.3 Noise Measurement 
The noise measurement algorithm is used to sort program during ATSS. This is done by the TV- 
microcontroller which reads the noise level in VSP. The value is determined by averaging over 
several fields. 
 
5.3.1.8.4 Operation Modes 
The interlaced input signal (e.g. 50 Hz PAL or 60 Hz NTSC) is composed of a field A (odd lines) 
and a field B (even lines). The 100Hz operation mode used is simply AABB, where each stored 
field in the memory is displayed double times on the TV screen.  
A still field can be displayed using FREEZE command, the operation mode becomes ABAB.  
5.3.1.8.5 Digital 656 Output 
The output data format corresponds to CCIR 656 with double-scan format (8-bit bus at a data 
rate of 54 MHz). There all frequencies and data-rates are doubled compared to standard 
CCIR656 specification. Timing reference codes (SAV, EAV) are inserted according to the 
specification. The output is set to 720 pixels per line and the display clock is set to 54 MHz. 
 
5.4.2 BACK END 
 
5.4.2.1  Digital Input Interface 
The digital input interface is set to receive 8 bit 4:2:2 Y Cr Cb multiplexed with separate H/V-
syncs and clock (ITU-R-656 format). The data inputs Y0...Y7 and C0...C7 are clocked with the 
external clock LLC2. The clock frequency is 54 MHz for 8 bit data input. The horizontal sync 
pulse at the HS pin should be an active video signal, which is not vertically blanked. A clock 
generator converts the different external line locked clock rates to a common internal sample rate 
of approximately 40.5 MHz, in order to provide a fix bandwidth for all digital filters. Therefore the 
input data is sample rate converted to the common processing frequency by the horizontal scaler. 
 
5.4.2.2 Horizontal Scaler 
The horizontal scaler supports linear or nonlinear horizontal scaling of the digital input video 
signal in the range of 0.25 to 4. Nonlinear scaling, also called “panorama vision”, provides a 
geometrical distortion of the input picture. It is used to fit a picture with 4:3 format on a 16:9 
screen by stretching the picture geometry at the borders. Also, the inverse effect can be 
produced by the scaler. See also microcontroller section to find details on format switching logic. 
 
 
						

							CP-850FX Service Manual 
 
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51 5.4.2.3  Luma Contrast and Brightness 
The luminance signal is multiplied by a factor of 0...2 (contrast adjustment). The signal can be 
shifted by ±100% of its maximal amplitude with the digital brightness value 
 
5.4.2.4  Black Level Expander/Compressor (BLEC) 
The black level expander/compressor modifies the luminance signal with an adjustable non-
linear function to enhance the contrast of the picture. 
Dark areas are stretched to black, while bright areas remain unchanged. Advantageously, this 
black level processing is performed dynamically and only if it will be most noticeable to the 
viewer. 
 
5.4.2.5 Luma Sharpness Enhancer (LSE) 
Sharpness is one of the most critical features for optimum picture quality. This important 
processing is performed in the LSE circuitry of DDP 3315C. It consists of the dynamic peaking, 
the luma transient improvement (LTI) and an adaptive mixer. The luma input signal is processed 
in the peaking and LTI block in parallel. Both output signals are combined in the mixer depending 
on the selected LSE characteristic. 
 
5.4.2.6 Dynamic Peaking 
The dynamic peaking improves the details of a picture by contour emphasis. It adapts to the 
amplitude and the frequency of the input signal. Small detail amplitudes are sharpened, while 
large detail amplitudes stay nearly unmodified. 
 
5.4.2.7 Luma Transient Improvement (LTI) 
For small detail amplitudes the dynamic peaking is the most appropriate processing to improve 
the sharpness. However, for large amplitudes even small over-and/ or undershoots of the 
peaking are too annoying. The luma transient improvement enhances the slope of picture detail 
without these effects by a non-linear processing. The contour correction signal calculated in this 
block, is limited to the adjacent extreme values to prevent over- and undershoots. The LTI 
features an adjustable gain control and an adjustable coring threshold to prevent the 
enhancement of small noise amplitudes. 
 
5.4.2.8  Mixing of Dynamic Peaking and LTI 
The contour correction signals of the dynamic peaking and the LTI block are combined by the 
mixer. Controlled by the amplitude of a picture edge, this circuitry fades between these two 
signals. Thus, small and medium picture detail is enhanced by contour emphasis (peaking) and 
large picture detail is enhanced by step-improvement (LTI). 
 
5.4.2.9  Chroma Transient Improvement 
The intention of this block is to enhance the chroma resolution. A correction signal is calculated 
by differentiation of the colour difference signals. The differentiation can be selected according to 
the signal bandwidth, e.g. for PAL/NTSC/SECAM or digital component signals, respectively. The 
amplitude of the correction signal is adjustable. Small noise amplitudes in the correction signal 
are suppressed by an adjustable coring circuit. To eliminate “wrong colours”, which are caused 
 
						

							CP-850FX Service Manual 
 
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52 by over and undershoots at the chroma transition, the sharpened chroma signals are limited to a 
proper value automatically  
 
 
  
a) Cr Cb input of CTI 
b) Cr Cb input + correction signal 
c) sharpened and limited Cr Cb
 
 
 
						

							CP-850FX Service Manual 
 
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53 5.4.2.10  Analog Back End 
The digital RGB signals are converted to analogue RGB by three 10-bit digital to analogue 
converters (DAC). Each RGB signal has two additional DACs with 9-bit resolution to adjust 
analogue brightness (40% of the full RGB range) and cutoff / black level (60% of the full RGB 
range). An additional fixed current is applied for the blanking level. 
The back-end supports the insertion of two external analogue component signals, only one is 
used for OSD/Text from the microcontroller. These signals are clamped, processed in an 
analogue matrix (RGB2), converted by a voltage/current converter (VCC), and inserted into the 
main RGB by the fast blank switch. The analogue RGB outputs are current outputs with current- 
sink characteristics. 
 
5.4.2.11  Analog RGB Insertion 
Each component signal is clamped, converted to RGB if required, and inserted into the main 
RGB by the fast blank switch. The external component signals are adjustable independently as 
regards DC level (brightness) and magnitude (contrast). 
Fast Blank selection logic Over-/underlay of the external component signal and the main RGB 
signal depends on the fast blank input signal. 
 
5.4.2.12  CRT Measurement and Control 
In order to define accurate colour on different CRT displays, the cut-off and white drive settings 
are adjusted in factory depending on the characteristic of CRT phosphor. 
To guarantee correct colours during the lifetime of the display, a build in automatic tube control 
loop measures and adjusts the black level on every field and white point every third field. The 
display processor is equipped with an 9/12-bit PDM-ADC for all picture tube measuring purposes. 
This MADC is connected to the SENSE input pin, the input range is 0 to 2.6 V. Cutoff and white 
drive current measurement are carried out with 8-bit resolution during the vertical blanking 
interval. The current range for cutoff measurement is set by connecting the sense resistor RC591 
to the SENSE input. Due to the fact of a 1:10 relation between cutoff and white drive current the 
range select 2 output (RSW2) becomes active for the white drive measurement and connects 
R533 in parallel to RC591, thus determining the correct current range. 
During the active picture, the MADC is used for the average beam current limiter
 with a 12-bit 
resolution. Again a different measurement range is selected with active range select 1&2 outputs 
(RSW1&RSW2) connecting R534 in parallel to R533 and RC591. 
These measurements are typically done at the summation point of the picture tube cathode 
currents. 
The picture tube measurement returns results on 
every field for: 
– cutoff R 
– cutoff G 
– cutoff B 
– white drive R or G or B (sequentially) 
 
The average beam current limiter (BCL) works on both the digital YC r C b input  from VSP and 
the inserted analog RGB signals (OSD and Teletext) by using the sense input for the beam 
current measurement. The BCL uses a different filter to average the beam current during the 
active picture resulting in a 12-bit resolution. The filter bandwidth is approximately 4 kHz. The 
beam current limiter allows the setting of a threshold current, a gain and an additional time 
constant. To accommodate several CRT’s, beam current threshold and gain can be modified by 
microcontroller option2. If the beam current is above the threshold, the excess current is low-
 
						

							CP-850FX Service Manual 
 
Europe R&D 
54 pass filtered with the according gain and time constant. The result is used to attenuate the RGB 
outputs by adjusting the white drive multipliers for the internal (digital) RGB signals, and the 
analog contrast multipliers for the analog RGB inputs, respectively. The lower limit of the 
attenuator is programmable, thus a minimum contrast can always be set. If the minimum contrast 
is reached, the brightness will be decreased to a programmable minimum as well.  
 
5.4.2.13  Synchronization and Deflection 
The deflection processing generates the signals for the horizontal and vertical drive. This block 
contains two numeric phase-locked loops and a security unit: 
– PLL2 generates the horizontal and vertical timing, e.g. blanking, clamping and sync signals. 
Phase and frequency are synchronised by the incoming sync signals. 
– PLL3 adjusts the phase of the horizontal drive pulse and compensates for the delay of the 
horizontal output stage. 
– The security unit observes the H-Drive output signal. 
With an external 5 MHz reference clock this unit 
controls the H-drive “off time” and period. In case of 
an incorrect H-drive signal the security unit generates 
a free running h-drive signal divided down from 
beam current 
 
5.4.2.14 EHT Compensation 
The vertical deflection waveform is scaled according the average beam current. This is used to 
compensate the effects of electric high tension changes due to beam current variations. EHT 
compensation for East/West deflection is done with an offset corresponding to the average beam 
current. 
 
5.5 MICRONTROLLER
 
5.5.1 MICROCONTROLLER FEATURES 
ƒ  8-bit 8051 instruction set compatible CPU 
ƒ  33.33-MHz internal clock (max.) 
ƒ 0.360 μs (min.) instruction cycle 
ƒ  Two 16-bit timers : schedule software tasks , and user clock 
ƒ Watchdog timer 
ƒ  Capture compare timer for infrared remote control decoding 
ƒ  Pulse width modulation unit (2 channels 14 bit, 6 channels 8 bit) : used to control AGC 
Take Over Point . 
ƒ  ADC (4 channels, 8 bit) : AFT, AGC, Local keys, OCP. 
ƒ UART 
5.5.2 ACQUISITION FEATURES 
ƒ  Multistandard Digital Data Slicer 
ƒ  Parallel Multi-norm Slicing (TTX, VPS, WSS) 
ƒ  Four Different Framing Codes Available 
ƒ  Data Caption only Limited by available Memory 
ƒ Programmable VBI-buffer 
ƒ  Full Channel Data Slicing Supported 
ƒ  Fully Digital Signal Processing 
ƒ  Noise Measurement and Controlled Noise Compensation 
 
						

							CP-850FX Service Manual 
 
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55 ƒ Attenuation Measurement and Compensation 
ƒ  Group Delay Measurement and Compensation 
ƒ  Exact Decoding of Echo Disturbed Signals 
 
 
5.5.3 PORTS 
ƒ  One 8-bit I/O-port with open drain output and optional I 2 C Bus emulation support (Port 0) 
ƒ  Two 8-bit multifunction I/O-ports (Port 1, Port 3) 
ƒ  One 4-bit port working as digital or analogue inputs for the ADC (Port 2) 
ƒ  One 2-bit I/O-port with secondary functions (P4.2, 4.3, 4.7) 
5.5.4 μ-CONTROLLER I/O PIN CONFIGURATION AND FUNCTION TABLE  
 
CONFIGURATION PIN NAME STAND BY TV ON DESCRIPTION 
3 S/SW2  Open Drain  Open Drain 
4 S/SW2  Open Drain  Open Drain  
5 OCP  Open Drain  Open Drain  Over Current Protection 
8 RESET out  Low  Open Drain  Reset video IC’s 
15 S/SW1 High impedance High impedance ADC input 
16 AGC in  High impedance High impedance AGC input – ADC input 
17 KEY  High impedance High impedance Keyboard input – ADC input 
18 AFT  High impedance High impedance AFT input– ADC input 
21 Mod SW  High impedance Push Pull High = Negative modulation, Low = 
Positive modulation (L/L’). 
22 SECAM L’  High impedance Push Pull  Low = L, High =L’ 
23 IR  High impedance High impedance Infrared Interrupt input 
24 SOUND INT  Input  input Sound interrupt input – edge 
triggered 
47 Sound Mute  Push Pull - Low  Push Pull - High Low=Mute 
48 AGC out  --  PWM out  Control tuner AGC (TOP) 
50 Relay  Push Pull - Low  Push Pull - High  
51 LED  Push Pull  Push Pull Low : LED Red 
High : LED Green 
52 Power  Push Pull - Low  Push Pull - HighSMPS operation mode 
High=ON, Low=ST-BY 
5.5.5 TUNING 
The AFC information is supplied by the demodulator IC, and becomes available on SDA55xx pin 
15 for controlling software. The controlling software uses this information for tuner frequency 
tracking ( automatic following ). The AFC windows is typically between 50 KHz and 100 KHz. The 
minimum frequency step of the tuner is 50 Khz. 
This AFC function is disabled when a program is tuned using the direct frequency entry or after 
fine tuning adjustment. Therefore it is recommended to tune channel with the TV search function 
( manual or ATSS ) or using the direct channel entry to enable the Automatic Frequency Control. 
#4 #3 Source L L Tuner L H AV2-16/9 H L  AV2-4/3 H H AV2-4/3 
 
						

							CP-850FX Service Manual 
 
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56 5.5.6 AUTOMATIC PICTURE FORMAT SWITCHING 
When AUTO mode is selected by the user, the television will automatically select the picture 
format for the user. If the user does not want to accept this selected format, he can always 
override the setting by use of the ZOOM control on the remote control. 
 
The received information used for automatic picture format control (only while AUTO is selected) 
is supplied from two sources; 
ƒ  By WSS data (Wide Screen Signalling Information : see the WSS European 
Telecommunication Standard ETS 300 294).  
ƒ  The voltage level from SCART 1 or SCART 2, pin 8 (slow switching) 
5.5.6.1 WSS Data 
This digital signal is a received at the beginning of line 23 in each frame. It is not a teletext signal, 
but the controller uses the same decoder resources to receive and decode the digital signal. 
This is bi-phase encoded using a clock frequency of 5 MHz. In total, 14 data bits are available, in 
4 groups. 
ƒ  Group 1 : Aspect Ratio    (b0, b1, b2, b3) 
ƒ  Group 2 : Enhanced Services  (b4, b5, b6, b7) 
ƒ  Group 3 : Subtitles      (b8, b9, b10) 
ƒ  Group 4 : Reserved   (b11, b12, b13) 
 
The signal contains bits in Data Group 1 which define an Aspect Ratio label, and in Data Group 3 
(b10) which defines if subtitles are available in the video. The other data groups have no 
application in this TV for picture format selection. 
The TV decoder recognises 5 bits of data (where b3 is an odd parity bit for Data Group 1). 
 
 Aspect WSS Bits Format  Name 
Position Ratio label 012310Tube 16:9 Tube 4:3 
N/A FORMAT_4_3 0 0 0 1 0 4:3 FULL SCREEN
CENTRE  FORMAT_14_9  1 0 0 0 0 ZOOM 14:9  FULL SCREEN
TOP FORMAT_14_9 0 1 0 0 0 DEFAULT DEFAULT 
CENTRE  FORMAT_16_9  1 1 0 1 0 ZOOM 16:9  FULL SCREEN
TOP  FORMAT_16_9  0 0 1 0 0 FULL SCREEN  FULL SCREEN
CENTRE FORMAT_16_9_PLUS  1 01 1 0 ZOOM 16:9  FULL SCREEN
CENTRE FORMAT_14_9_FULL 0 1 1 1 0 FULL SCREEN  14:9 
N/A FORMAT_16_9_ANAM 1 11 0 0 FULL SCREEN  16:9 
N/A  SUBTITLE_OUT_IMAGE  X X X X 1 FULL SCREEN  FULL SCREEN
 
There are the following output possibilities; 
ƒ 4:3 
ƒ 14:9 
ƒ 16:9 
ƒ ZOOM 14:9 
ƒ ZOOM 16:9 
ƒ  FULL SCREEN (for either 4:3 or 16:9 tubes) 
 
DEFAULT refers to a signal for which there is no implementation, so is treated as if there is no 
signal data available. 
 
						

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57 5.5.6.2  SCART Pin 8 Data (Slow Switching) 
When there is a signal from SCART 1 pin 8 or SCART 2 pin 8 (named the Slow Switching SSW 
signal) the TV will enter AV mode, unless the user forces another source (which is possible even 
though slow switching is present). 
 
 Aspect Switching Format  Name 
Position Ratio Voltage Level Tube 16:9 Tube 4:3 
CENTRE 4:3 HIGH 4:3 FULL SCREEN 
CENTRE 16:9 MEDIUM FULL SCREEN 16:9 
 
The SCART 1 signal SSW1 has priority over SSW2. 
5.5.6.3  Picture Format Description 
From the information collected from the above sources is the input, from which the TV must 
decide which format to select. The WSS data always has priority over Slow Switching. 
 
If no valid data is received from either source, then a default value must be assumed (this is 
controlled also by the user by the use of “ZOOM AUTO” in the “FEATURES” menu). 
5.3.1.8.1 16:9 CRT 
Formats available with 16:9 cathode ray tube; 
ƒ 4:3      (AUTO selectable) 
ƒ 14:9     (AUTO selectable) 
ƒ  ZOOM 14:9    (AUTO selectable) 
ƒ  ZOOM 16:9    (AUTO selectable) 
ƒ  FULL SCREEN  (AUTO selectable) 
ƒ  PANORAMA   (only available/selectable by the user) 
ƒ  FAVOURITE   (only available/selectable by the user) 
 
The table below gives a summary of the FORMAT modes available with a 16:9 CRT, and their 
given properties. 
 
 Zoom factor – 16:9 CRT  
Format Name Vertical HorizontalDescription Application 
4:3 100% 75% Picture is centred with 
black bars at the left and 
right hand side of the 
display Standard 4/3 picture 
with 576 active lines 
14:9 114% 87% Picture is centred with 
black bars at the left and 
right hand side of the 
display 14:9 picture – letter 
box format with 504 
active lines 
ZOOM 14:9  114%  100% Picture is displayed filling 
the full width of the screen 
by incorporating a small 
horizontal geometrical 
error (typically 8% linear) 14:9 picture – letter 
box format with 504 
active lines 
ZOOM 16:9  133%  100% Picture is displayed filling 
the full screen (width and 
height) 16:9 picture – letter 
box format with 430 
active lines 
 
						

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58 FULL SCREEN  100%  100% Picture is displayed filling 
the full screen (width and 
height) Standard 16/9 
picture with 576 
active lines 
PANORAMA 
(not AUTO) 100% 100% Picture is displayed filling 
the full screen (width and 
height) by incorporating a 
non-linear horizontal 
geometrical error Used to fit a picture 
with 4:3 format on a 
16:9 screen by 
stretching the picture 
geometry at the 
borders 
FAVOURITE 
(not AUTO) 100% to 
133% 75% to 
100% Customised picture size  User-definable 
format. 
5.3.1.8.2 4:3 CRT 
Formats available with 16:9 cathode ray tube; 
ƒ 14:9     (AUTO selectable) 
ƒ 16:9     (AUTO selectable) 
ƒ  FULL SCREEN  (AUTO selectable) 
ƒ WATERGLASS  (only available/selectable by the user) 
ƒ  FAVOURITE   (only available/selectable by the user) 
 
The table below gives a summary of the FORMAT modes available with a 4:3 CRT, and their 
given properties. 
 
 Zoom factor – 4:3 CRT   
Format Name Vertical HorizontalDescription Application 
14:9 87% 100% Picture is centred with 
black bars at the top and 
bottom of the display, 
realised by compressing 
the vertical size 14:9 picture – letter 
box format with 576 
active lines 
16:9 75% 100% Picture is centred with 
black bars at the top and 
bottom of the display, 
realised by compressing 
the vertical size 16:9 picture – letter 
box format with 576 
active lines 
FULL SCREEN  100%  100% Picture is displayed filling 
the full screen (width and 
height) Standard 4:3 picture 
with 576 active lines 
WATERGLASS 
(not AUTO) 100% 100% Picture is displayed filling 
the full screen (width and 
height) by incorporating a 
non-linear horizontal 
geometrical error Used to fit a picture 
with 16:9 format on a 
4:3 screen by 
compressing the 
picture geometry at 
the borders 
FAVOURITE 
(not AUTO) 100% to 
133% 75% to 
100% Customised picture size  User-definable 
format. 
 
 
						

							CP-850FX Service Manual 
 
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59 5.5.7  EXTERNAL SOURCE CONTROL LOGIC 
The following schematic, illustrates the logic of control for the two SCART connectors. 
 
 
The terms used in the schematic are described below; 
 
1.  AUTO represents a situation where the television has self-selected its picture source. This 
could be when the SCART SLOW SWITCHING pin has gone to a high state, and the AV 1 
input is selected without the intervention of the user. 
2.  FORCED represents the change of source which has been commanded by the user (using 
the EXTERNAL button). The user always has priority, and can override the AUTO change of 
source by the television. 
3.  AV KEY represents the EXTERNAL button of the remote control, or on the television. 
4.  S/SW 1, or S/SW 2 represent the SLOW SWITCHING inputs of the first SCART (AV 1) or 
second SCART (AV 2), these each being pin number 8. 
5.  F/SW 1 represents the FAST SWITCHING input of the first SCART (AV 1), on pin number 16. 
The second SCART, AV 2, input does not possess a FAST SWITCHING input. 
 
The HIGH state of a slow switching input represents the request from the external source to be 
selected by the television. Whether this is accepted or not depends on the position in the logic 
diagram. The general rule is that the user always has priority, so the use of the AV KEY will 
always result in a defined logic path being followed. 
Under certain circumstances, defined in the diagram, the change of state of a slow switching 
input will result in the automatic change of source by the television. This change, such as the 
change from RF broadcast to the AV 1 input, can always be overridden by the user after the 
event. 
Each line on the diagram, with its associated text, represents the exact conditions under which 
the change of state will occur. Sometimes this will be accompanied by another action which will 
be automatically performed by the television, being to either ENABLE or DISABLE F/SW 1.