Daewoo Dtf 2950 Service Manual
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Page 61
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,...
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CP-850FX Service Manual Europe R&D 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...
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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...
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CP-850FX Service Manual Europe R&D 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...
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CP-850FX Service Manual Europe R&D 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...
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CP-850FX Service Manual Europe R&D 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...
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CP-850FX Service Manual Europe R&D 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...
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CP-850FX Service Manual Europe R&D 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...
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CP-850FX Service Manual Europe R&D 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...
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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...