Daewoo Dtf 2950 Service Manual

CP-850FX Service Manual 
 
Europe R&D 
60  
5.5.8  OVER CURRENT PROTECTION 
In case of overload, the SMPS secondary voltages will drop. The voltage on pin 5 of  
microcontroller changes Low to High. The controlling software which continuously monitors this 
voltage will switch the set to stand by mode. To power on the set again the user must switch it off 
using the main power switch. Appropriate hysteresis guaranty a reliable operation. 
 
5.6 TELETEXT DISPLAY
 
National character option bits C12, C13,...

CP-850FX Service Manual 
 
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61  
OSD Language C12 C13 C14 PRIMARY 
LANGUAGE Secondary Language X26 Language
0 0 0  English  English  West Euro 
0 0 1  German  German  West Euro 
0 1 0  Scandinavian  Scandinavian  West Euro 
0 1 1  Italian  Italian  West Euro 
1 0 0  French  French  West Euro 
1 0 1  Spanish  Spanish  West Euro 
1 1 0  Turkish  Turkish  West Euro 
English, French, 
German, Italian, 
Spanish, Dutch, 
Danish, Finnish, 
Norwegian, 
Swedish, Greek 
1 1 1  Greek  English  Greek 
0 0...

CP-850FX Service Manual 
 
Europe R&D 
62 5.7.4 NICAM DECODER 
In case of NICAM - mode, the phase samples are decoded according the DQPSK - coding 
scheme. The output of this block contains the original NICAM bitstream. 
 
5.7.5 DSP SECTION 
All audio baseband functions are performed by digital signal processing (DSP). The DSP section 
controls the source and output selection, and the signals processing. 
 
5.7.6  SOUND MODE SWITCHING 
In case of NICAM transmission, the controlling software read the bit...

CP-850FX Service Manual 
 
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63 5.8.2 MODE SELECTION 
The TDA8946J has several functional modes, which can be selected by applying the proper DC 
voltage to pin MODE. 
 
Mute : In this mode the amplifier is DC biased but not operational (no audio output). This allows 
the input coupling capacitors to be charged to avoid pop-noise. The devices is in mute mode 
when 2.5 V < V
MODE < (Vcc-1.5 V). 
 
Operating : In this mode the amplifier is operating normally. The operating mode is activated at...

CP-850FX Service Manual 
 
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64 5.10  POWER SUPPLY (STR-W6754) - Functions of Each Terminal
 
5.10.1 Vcc Terminal (Pin 4) 
5.10.1.1 Start-up Circuit 
The start-up circuit detects Vcc terminal (No.4 pin) voltage, 
and makes a control IC start and stop. The power supply of the 
control IC (Vcc terminal input) employs a circuit as shown in 
Fig.1.  At start-up, C3 is charged through a start-up resistor R2.  
The R2 value needs to be set more than the holding current of 
the latch circuit (150µA...

CP-850FX Service Manual 
 
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65 5.10.1.2 Auxiliary/Drive Winding 
After the control circuit starts its operation, the power 
supply is gained by rectifying and smoothing the 
voltage of the auxiliary winding D.
  
 Fig.3 shows the start-up voltage waveform of the 
Vcc Terminal.  The auxiliary winding voltage does  
not rise up to the set voltage after the control circuit 
starts its operation, and the Vcc terminal voltage 
starts falling.  However, because the operation stop 
voltage is set as...

CP-850FX Service Manual 
 
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66 5.10.1.3 Overvoltage Protection Circuit 
Where the voltage exceeding 27.5V(TYP) is imposed on between Vcc and GND terminals, the 
OVP circuit of the control IC starts its operation and turns latch-mode, and the control IC stops its 
oscillation.  Generally, the Vcc terminal voltage is supplied from the auxiliary winding of the 
transformer, and the voltage is in proportion to the output voltage; thus, the circuit also operates 
at that time when the overvoltage...

CP-850FX Service Manual 
 
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67 5.10.1.4   Latch Circuit 
The latch circuit is a circuit that holds the oscillator output low and stops the power supply circuit 
operation when OVP or OLP circuit operates.  The holding current of the latch circuit is 150µA 
MAX (Ta = 25C) when the Vcc terminal voltage is minus 0.3V to the operation stop. 
In order to avoid improper operations caused by noises, etc., the delay-time is provided with a 
timer circuit incorporated in the HIC, and thereafter, the...

CP-850FX Service Manual 
 
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68 5.10.2.2 Overload Protection 
 
The output characteristics of the secondary side at the time 
when the OCP circuit operates, due to the overload of the 
secondary side output, is shown in Fig.8.  Where the output 
voltage falls below the overload mode, the auxiliary winding 
voltage of the primary side also falls proportionally, and the 
Vcc terminal voltage falls below shutdown voltage to stop the 
operation.  In that case, as the circuit current is also...

CP-850FX Service Manual 
 
Europe R&D 
69 The time until the latch protection operation starts its operation can be calculated from the 
following formula since the I
SSOLP(OLP) is a constant current circuit.  That is,  
 
C (Condenser Capacity)  x ⊿V(Condenser Charging Voltage: approx. 5V) = I
SSOLP (OLP) x t (time) 
…… (2) 
 
While, the ISSOLP(OLP) contains the voltage dependent characteristics on SS/OLP terminal 
voltage, and ISSOLP(OLP) falls when SS/OLP terminal voltage rises.  The actual value does...