LA-E791P Rev 2.0 motherboard (commonly used in HP 15-bs series laptops), a highly useful piece of information for troubleshooting power issues is the SMBUS Address Table Primary Power Rail sequence Critical SMBUS & Power Address Table
Before diving into complex logic, verify these basic rails in order. If any of these are missing, the laptop will not reach the S0 (fully on) state: : Essential for the Embedded Controller (EC) to start. +3VALW / +5VALW
: "Always-on" rails that must be present even when the laptop is off but plugged in. la-e791p rev 2.0 schematic
: The enable signal from the EC to turn on the main power supplies.
How to diagnose No +VCC_CORE - LA- E791P Rev 2.0 - No display - SOC Problem - YouTube. This content isn't available. lalbabu.p.s.sahani LA-E791P Rev 2
connections to the charger IC and battery, as communication errors here often prevent charging even if the DC jack is fine. Schematic Access
: 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 : The enable signal from the EC to
, such as a dead board or no display, so I can provide more targeted test points?
How to diagnose No +VCC_CORE - LA- E791P Rev 2.0 - No display 7 Aug 2022 —
: You can find the full Rev 2.0 diagrams on professional repositories like or via repair communities on Are you currently troubleshooting a specific fault
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