Acer Spin 1 SP111-33 Power-On Issue (Troubleshooting Assistance)

[justice171]

I am seeking guidance on an Acer Spin 1 SP111-33 that does not turn on when pressing the power button.

Below are the observations and troubleshooting steps I have taken so far: Observations and Tests:

1. Verified that all critical voltages are present:
   • 3.3V and 5V are always present if DC is plugged.
   • 1.8V on the BIOS chip is present.
2. Checked the power button functionality:
   • When pressed, the voltage drops to 0V, indicating the button is functional.
3. Inspected the flex cable connecting the USB, audio, and power button to JUB1:
   • Confirmed connectivity is intact, ruling out issues with the flex cable.
4. Replaced the following components with known working ones:
   • BIOS chip
   • KBC/EC Super I/O

Additional Details:

• When only the battery is connected (DC adapter unplugged):
  • Pressing the power button causes the 3.3V and 5V rails to come up briefly and then disappear.
• When the DC adapter is plugged in:
  • The 3.3V and 5V rails remain present, but pressing the power button has no effect (no changes observed).

Despite these efforts, the laptop still does not power on. Current Suspicions:


I suspect there may be an issue in the power circuit, potentially involving a damaged diode or another failed component. However, I am uncertain about how to proceed in pinpointing the fault.

I have attached the schematic and board viewer for your reference. Could you please advise on the following:

1. Additional areas or components to test within the power circuit.
2. Specific diodes or MOSFETs to inspect in this model.
3. Any additional measurements or steps to confirm the fault location.

I would greatly appreciate your guidance in resolving this issue. Please let me know if further details or measurements are required.

Thank you for your support and expertise!