: "Always-on" rails that must be present even when the laptop is off but plugged in.
: Usually the last rail to appear; if this is missing but others are present, you likely have an SOC (System on Chip) or CPU power management issue. Troubleshooting Tips No Display? A common failure point on this revision is the or a lack of Not Charging? Focus on the la-e791p rev 2.0 schematic
: The enable signal from the EC to turn on the main power supplies. : "Always-on" rails that must be present even
If you are troubleshooting a "No Power" or "No Display" condition, checking these specific SMBUS addresses can help identify which component (Battery, RAM, or PCH) is failing to communicate: SMBUS Port 7-bit Address 8-bit Write 8-bit Read Battery (BAT) DIMM1 (RAM) Charger (CHGR) Thermal Sensor Common Power Rails to Probe A common failure point on this revision is
connections to the charger IC and battery, as communication errors here often prevent charging even if the DC jack is fine. Schematic Access