hardware-boardview-skilllisted

# Hardware Boardview & Circuit Diagnostics Skill Standard operating procedure from the Megapass Intra Solusindo hardware repair bench for diagnosing dead motherboards, short-to-ground conditions, power rail sequencing failures, and silicon punch-through hazards. --- ## 1. Circuit Integrity & Impedance Baseline Before applying DC adapter power or suspecting primary controllers (Super I/O, PCH, SoC, CPU): 1. **Never plug an OEM charger into a dead board** without taking passive cold measurements first. 2. Measure resistance to ground (impedance) across all primary buck converter coils in 200Ω resistance mode: - **Main System Rail (`VIN / B+`)**: Must read >100kΩ. If 0Ω–5Ω, a high-side MOSFET or primary filtering MLCC is dead short. - **Always-On (`+3VALW` / `+5VALW`)**: Must read >50Ω (typically 1kΩ–50kΩ). Under 5Ω indicates a catastrophic secondary short. - **RAM Rail (`+1.2V_DDR4` / `+1.1V_DDR5`)**: Typically 100Ω–500Ω. - **PCH / System Agent (`+1.05V_PCH`)**: Typically 20Ω–80Ω. - **CPU Core (`+VCC_CORE`) & GPU Core (`+VCC_GT` / `VGPU`)**: **Normal baseline is ultra-low: 0.2Ω to 2.5Ω**. Do NOT misdiagnose this normal semiconductor resistance as a short circuit! --- ## 2. High-Side MOSFET Punch-Through Verification (CRITICAL HAZARD) A common fatal mistake is injecting voltage into a coil while its High-Side (upper) MOSFET is internally shorted between Drain and Source: ``` [ 19V VIN / B+ Main Rail ] │ [ Drain (D) ] ┌─────┴─────┐