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Lenovo B590 cannot be powered on for maintenance after charging for one night
Machine model: Lenovo B590
Malfunction: Notebook Won’t Turn On
Maintenance process: Disassemble the machine, the board number is LA-58,multimeter diode red pen GND starts typing diode value.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 1.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 2.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 3.
The measured CPU value is normal (as the diode diode value of MOSFET is very low, it is normal as long as it is not completely equal to 0).
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 4.
Memory VCC value is normal.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 5.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 6.
The value of 3V5V is normal.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 7.
The bridge is normal.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 8.
At last, when the common point is tested, it is found that the value is abnormal Short circuit. If the problem is determined, use Current heating test Dafa taught by the captain!
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 9.
Plug in my DIY numerical control power supply, and the VCC 10 current 10A will be finished.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 10.
After one operation, it was found that Capacitor of bridge VCC was broken. After removal, it was found that the common point value was still Short circuit. After burning, it was found that the chip Capacitor of VIN of CPU main VCC PWM chip was also broken, and the measured value had returned to normal after removal.
Lenovo B590 cannot be powered on for maintenance after charging for one night Figure 11.
After patching the damaged patch Capacitor, the power-on current runs up, and the screen lights up. After installation, there is no problem, and the maintenance is over.
