Panasonic A-300MU type DVD machine in the process of optical disc, figure sound suddenly disappeared, all the functions of failure repair method of fault -Service Manual Download|Circuit Download|Download Drawings|schematic download|route map download|free download user manual

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Panasonic A-300MU type DVD machine in the process of optical disc, figure sound suddenly disappeared, all the functions of failure repair method of fault

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Error voltage sampling, detection, amplification transmission circuit by VT1101, VT1102, VT1031, VD1101, Rll01, R1102 element composition and so on.

Including VT1101 for error voltage detection and tube, VT1102 tube with VD1101 zener diode together constitute the reference voltage circuit.

The circuit is more special, increased the VT1102 tube, increase VTl102 tube in order to make the error detection circuit is the purpose of the reference voltage has strong load capacity, won't because of current sampling circuit and affect the stability of the reference voltage. Here is the source of the error voltage and the power supply voltage stabilizing process.

1. The source of the error voltage

Error voltage from T1011 switch transformer windings (15) - (16) of the output pulse voltage > VD1111 rectifier and Cllll capacitance and Lllll inductance filter after 6 v voltage output. After Rll01 and R1102 resistance partial pressure, the voltage gain of about 5.1 V voltage is added to the VT1101 tube base.

Tl01l error of the reference voltage from the switch circuit transformer windings (17) ~ (15) of the output pulse voltage - VD1131 rectifier, C1131 capacitor filter after get the 12 V voltage - R1107 resistance - VD11001 tube voltage of 5.2 V, added to the VT1102 tube base. After shot with the device from the emitter to error detection amplifier tube VT1101 emitter provides some reference voltage of 4.5 V.

2. The power supply voltage stabilizing process

When switching power supply for some reason the Tl011 transformer voltage rise twice - Cllll capacitance 6 v the voltage on both ends - VT1101 tube voltage increases, the collector current increase and smaller resistance and photoelectric coupler VT1031 within the brightness of the light emitting diode enhancement - VT1031 photoelectric triode conduction degree increase, resistance decrease. In this way, the photoelectric coupler in photosensitive pipe the voltage on the collector is because VT1031 photosensitive resistance decreases and added to the thick film IC1011 piece of 6 feet, and make the foot voltage rise. The rise in voltage into the oscillator within IC can make the oscillator output pulse width after - IC switch tube in VT oscillation pulse as ahead of time, the duty ratio decreasing to decrease the energy stored in the transformer Tl011 switch, so that the output voltage drops, achieve the goal of a stable output voltage.

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