VESTEL DVD4250D, DVD-плеер

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0 to 0.4V : TV is driven by the composite video input signal (pin 19).
Left unconnected, it is pulled to 0V by its 75R termination.
1V to 3V : the TV is driven by the signals Red, Green, Blue and composite sync. The latter is sent to the
TV on pin 19. This signal is useful when using a TV to display the RGB output of devices such as home
computers with TV-compatible frame rates. Tying the signal to 5V via 100R forms a potential divider
with the 75R termination, holding the signal at around 2V. Alternatively, if a TTL level (0 to 5V)
negative sync pulse is available, this will be high during the display periods, so this can drive the
blanking signal via a suitable resistor.
Control Voltage
0 to 2V = TV, Normal.
5 to 8V = TV wide screen
9.5 to 12V = AV mode
13. CIRCUIT DESCRIPTION
13.1 POWER SUPPLY:
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Socket PL2 is the 220VAC input.
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Socket PL3 is used for the power button on the front panel.
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3.15A fuse F1 is used to protect the device against short circuit.
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Voltage is rectified by using diodes D1, D2, D3 and D4. Using capacitor C33 (47
?
f) a DC voltage is
produced. (310- 320VDC).
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The current in the pri mary side of the transformer TR2 comes to the SMPS IC (TNY267P). It has a built -in
oscillator, over current and thermal protection circuitry and runs at 133kHz. It starts with the current from
the primary side of the transformer and fo llows the current from the feedback winding.
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Voltages on the secondary side are as follows: 12 Volts at pin11 at C42, 5 Volts at C40,3.3 Volts at C38,
-22Volts at C44,-12 Volts at D22.
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D14 TL431 is a constant current regulator. TL431 watches the 5 volts and supplies the required current to
IC2. There are a LED and a photo transistor in IC2. The LED inside the IC2 transmits the value of the
current from D25 to phototransistor. Depending on the current gain of the phototransistor IC3 keeps the
voltage on the 5-volt-winding constant.
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–22 Volts is used to feed the VFD (Vacuum Fluorescent Display) driver IC on the front panel.