Schematic Work _best_ — Bdl51 Lad711p Rev 30

| Symptom | Likely Cause | Schematic Area | Check | | :--- | :--- | :--- | :--- | | Fuse blown, dark marks | Shorted MOSFET or bridge rectifier | Primary (Block A & C) | Measure resistance across main capacitor terminals (should climb to >100kΩ). | | Fuse OK, but no 5VSB | Startup resistor open | Block B (Standby) | Locate high-value resistor (1-4.7MΩ) from +300V to standby IC VCC. | | 5VSB present, but no PS-ON | Main board failure | Connector pin (e.g., CN701 pin 2) | Force PS-ON with 1k resistor to 5VSB to test PSU alone. |

Repairing these boards requires verifying voltages in a specific order. If any rail is missing, the next stage will not trigger. LA-D711P No Display | Laptop Repairing Full Course bdl51 lad711p rev 30 schematic work

Before applying power, measure the resistance on all large inductors (coils). A low resistance (near 0 ohms) usually indicates a shorted capacitor or a failed IC on that specific rail (e.g., +1.0VALW, +1.8VALW). | Symptom | Likely Cause | Schematic Area