Before the user presses the power button, the motherboard must generate standby voltages to power the Embedded Controller (EC/SIO) and the power management section of the PCH.
: DDR4 SO-DIMM supporting up to 4 memory slots System Voltage Input : 19.5 V DC input rail
The PWM controller produces the 3.3V and 5V standby voltages required for the EC. apw70 lac391p schematic portable
The fault lies in the entry protection circuitry. Check the first and second input MOSFETs for gate voltage saturation.
. If these are shorted, the board won't take power from the charger. BIOS Chip: Before the user presses the power button, the
Before applying power, check the resistance on all major coils (3.3V, 5V, RAM, PCH, CPU). Low resistance on CPU/PCH coils (1–10 Ohms) is normal, but a low reading on 3.3V or 5V coils indicates a direct short.
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. Check the first and second input MOSFETs for
If you are currently diagnosing a specific issue on an APW70 LA-C391P board, please share the you are seeing (e.g., completely dead, spins fan but no display, amber charging light blinking) or any voltage measurements you have already taken on the main coils. Share public link
: Designed for Intel mobile architectures (typically 6th Gen Skylake in the ZBook 17 G3).
: Detailed circuit diagrams are often hosted on specialist repair repositories like Laptop-Schematics or a guide on how to locate a short on this specific board?