: Always-on voltage rails generated immediately after plugging in power. These run the Embedded Controller (EC) and standby circuits.
Locate the two input N-Channel MOSFETs near the charging IC. Check if the Gate voltage is being pulled up to roughly 25V by the charging controller. If the gate voltage is low, replace the charging IC or check its ACIN/ACOK pins. Step-by-Step Diagnostic Strategy Using the Schematic
Is the LAC391P sending the enable signal? If not, the issue is with the controller (LAC391P) or logic circuit. apw70 lac391p schematic portable
The output voltage is fed back to the to maintain a stable output voltage (e.g., 1.0V1.0 cap V for CPU/GPU). D. LAC391P Monitoring
Memory and display processing are handled directly by the integrated Intel HD Graphics within the SoC. Video outputs are routed via eDP (Embedded DisplayPort) to the internal LCD panel and via HDMI for external displays. Memory and Storage Interfaces Check if the Gate voltage is being pulled
If the board has standby voltages but refuses to turn on, use the search function in your PDF reader to locate the power button signal ( ON/OFF# ) and trace it directly to the EC pinout. Ensure the signal drops to 0V when the button is physically pressed and returns to 3.3V when released.
If a main power rail shows a true short circuit (0 to 2 Ohms): If not, the issue is with the controller
, a mobile workstation known for its robust build and high-end processing power.
: It features high-density components such as professional discrete GPUs, multiple DDR4 SO-DIMM slots, and M.2 storage interfaces. Where to Find Schematics and Boardview
Used to set the output voltage via a resistor divider. UGATE/LGATE: Gate drive signals for the external MOSFETs. EN (Enable): Logic high to turn on the regulator. 🛠️ Common Repair Scenarios No Power / No Charging:
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.