1, adjust the menu garbled, is the motherboard failure, replace the main chip or memory, or directly replace the motherboard. Black screen fault, most of the backlight circuit fault, a small part of the motherboard fault. The white screen common problem is that the DC-DC circuit on the screen logic board is bad, which can be solved by replacing the DC-DC circuit and can be repaired without changing the board.
2, N801 (FAN7602B) is a green current mode pulse width modulation controller for flyback PWVoltage, according to the TPS65161 specifications or data manual, confirm that the output voltage is within the expected range, if the output voltage is abnormal or no output, is an indication of the fault of the TPS65161.
5, chip pin definition: pin 1IN1, input signal, high level effective, output to the CPU pin 25. Pin 2IN2, input signal, active at high level, output to pin 24 of CPU. Pin 3IN3, input signal, active at high level, output to pin 23 of CPU.
6. XTALXTAL2 pin. This type of pin belongs to external connectionThe clock pin. The former is the input of the on-chip oscillation circuit, and the latter is the output of the on-chip oscillation circuit. RST pin.
1, LM2575 is a DC-DC switching power supply integrated circuit, the input voltage is up to 40V and 60V two, model HV is the high voltage version of 60V. There are also a variety of output voltage specifications, 3V, 5V, 12V, 15V, adjustable output voltage versions. Attached is a fixed voltage version of 0V.
2, the maximum output current is 1A 2576 The maximum output current is 3A Other parameters are exactly the same.
1, the control circuit is a pulse width modulator, which is mainly composed of sampler, comparator, oscillator, pulse width modulation and reference voltage circuits. This part of the circuitIt has been integrated and made into various integrated circuits for switching power supplies. The control circuit is used to adjust the switching time ratio of the high frequency switching element to achieve the purpose of stabilizing the output voltage.
2, the start and stop of VT1 is like a conductor's baton, driving the fluctuation of the current, forming a self-excited oscillation, and the push-pull power supply creates a stable and efficient output voltage through the tacit cooperation of VT1 and VT2. Buck, boost, reverse, each mode is like a variation in the circuit, adapting to the needs of different scenarios.
3, the principle of buck circuit is a step-down) The converter is composed of a switching element and an inductor. Stretch phase (switch off) : When the MOSFET switch is off, the input voltage is connected to the inductor, which stores the current.
4, as shown in the above figure for the self-excited series switching power supply structure schematic.
5, the main circuit of the switching power supply is composed of the input electromagnetic interference filter (EMI), the rectifier filter circuit, the power conversion circuit, the PWM controller circuit, the output rectifier filter circuit. The auxiliary circuit has input over and under voltage protection circuit and output over and under voltage protectionIf no, replace the parts if they are damaged.
First of all, use a multimeter to detect which part of the switching power supply is the problem; Then check the factor module and pulse width modulation module; Then see if the voltage of the line can reach 380 volts, if it does not reach this voltage value, it can be judged that the resistance is damaged, and a new resistor needs to be replaced.
Switching power supply maintenance resistance measurement first (1) Open the boot cover, turn over the circuit board, first test the power adjustment tube 0801 (BUZ91A) D pole is short circuit to the ground.