If the laptop shows absolutely no signs of life and draws zero current from the DC power supply, the N-Channel or P-Channel protection MOSFETs near the DC input jack are likely damaged or turned off by the charging IC.
Gently touch the side of the chip with tweezers. When the solder liquefies completely, lift the chip straight up. Preparing the Pads
Open circuit in the DC-IN path. Check the input protection MOSFETs or current sensing resistor. laptop motherboard chip level repair guide pdf
The Ultimate Laptop Motherboard Chip-Level Repair Guide Laptop motherboard chip-level repair is the highest echelon of hardware troubleshooting. Instead of replacing an entire expensive logic board, chip-level technicians isolate and replace individual micro-components like capacitors, resistors, MOSFETs, and Integrated Circuits (ICs).
With the motherboard completely disconnected from any power source (no battery, no CMOS battery, no charger): Set your multimeter to or Diode mode . Connect the black probe to a known chassis ground. If the laptop shows absolutely no signs of
Shorted MLCC Diagnostic: [Power Supply: 1V, 2A] ──> [Shorted 19V Rail] ──> [Faulty MLCC heats up] ──> [IPA Evaporates]
Indicates a catastrophic short, often a shorted high-side MOSFET or ceramic capacitor. Preparing the Pads Open circuit in the DC-IN path
Connect the power supply. Work sequentially down the power-on hierarchy. Measure voltage at the input MOSFETs, then the 3.3V/5V coils, and finally the CPU/RAM coils. Pinpoint exactly where the voltage chain breaks. Step 4: Voltage Injection for Shorts
Hold the nozzle perpendicularly about 1–2 cm above the chip and move it in small, continuous circles.
If you are looking for specific hardware assistance, please provide details such as the (e.g., LA-A991P, 820-00165), the exact symptoms you are experiencing, and any voltage measurements you have already taken. This will allow for more targeted troubleshooting advice. Share public link
Apply a generous amount of tacky flux around the perimeter of the IC.