The Acer One 14 Z1402 is a staple of the budget computing segment, built upon the Wistron Woody (14276-1) motherboard architecture. This platform typically features Intel Braswell or Bay Trail-M SoC (System-on-Chip) designs, where the CPU, GPU, and PCH are integrated into a single package. For the chip-level technician, this means precise voltage regulation is critical, as any spike on the secondary rails can directly kill the primary SoC. In this guide, we break down the Wistron power-up sequence and provide the essential engineering files for successful motherboard recovery.
Board Architecture & Technical Specifications
| Feature | Specification / Component |
|---|---|
| Motherboard Model / ODM | Wistron Woody 14 (14276-1 / 14276-2) |
| Chipset / CPU Architecture | Intel Braswell SoC (e.g., Celeron N3050 / Pentium N3700) |
| Super I/O (EC/KBC) | ITE IT8587E / IT8987E |
| Charging IC | Texas Instruments BQ24735RGRR |
| Main Power Rails | DCBATOUT, 3D3V_AUX_S5, 5V_AUX_S5, 1D35V_S3, 1D05V_VCCST |
Real-World Motherboard Diagnostic Procedures
1. DC-IN Protection & DCBATOUT Generation
On the Wistron Woody platform, the first point of failure is often the input MOSFETs (PU4401/PU4402). If the laptop is completely dead with no lights, measure DCBATOUT at the current sense resistor PR4417. If you see 0V, check the BQ24735 Charging IC. Pin 20 (VCC) must have 19V, and Pin 6 (ACDET) should be approximately 2.6V via the resistor divider. Crucially, check Pin 4 (ACDRV); it should be ~25V to drive the N-channel gates. If ACDRV is low, check for a short-circuit on the main rail (DCBATOUT) by measuring resistance to ground at PR4417; a reading below 10 ohms indicates a shorted decoupling capacitor or high-side MOSFET.
2. Standby Rail Analysis (3.3V/5V Buck Converter)
The 3D3V_AUX_S5 and 5V_AUX_S5 rails are generated by the PWM controller (commonly TPS51225 or similar). Before checking the coils (PL4501/PL4502), verify the LDO outputs: VREG3 and VREG5. These are essential for the EC (ITE IT8587E) to wake up. In the Acer Z1402, a common failure is the 3.3V rail being pulled down by a faulty SoC or a leaky ceramic capacitor near the Wi-Fi slot. Resistance to ground on the 3.3V coil should be in the kilo-ohm range. If it's below 50 ohms, the SoC is likely damaged.
3. Power-On Sequence & Signal State Tracking
To diagnose a "No Power-On" state where standby voltages are present, monitor the following Wistron-specific signals in order:
- KBC_PWRBTN#: Should drop to 0V when the power button is pressed and return to 3.3V.
- PM_SLP_S4# / PM_SLP_S3#: These signals must be released by the Intel SoC. If these remain at 0V after the button press, the SoC is not receiving the RSMRST# signal or the BIOS (U12) firmware is corrupted.
- ALL_SYS_PWRGD: This signal combines the "Power Good" status from all secondary regulators. If this is missing, the CPU VCORE will never initialize. Always verify the 1.05V VCCST rail before condemning the SoC.
Download Schematic & Boardview Files
Direct download link. Verified Wistron Woody 14276-1 schematic archive.
Professional Repair Assistance
Explore our technician resources:
- 🛠️ Diagnose No-Power & Short-Circuit faults step-by-step: Interactive Laptop Diagnostic Lab
- 🛒 Original Replacement Motherboards & IC Components: Official Spare Parts Mega Store
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