Let’s dissect the schematic by its major modules.
The La-e791p follows a standard AMD mobile sequence but with HP-specific SIO enabling.
| Rail | Name | Source | Enables Next | |------|------|--------|----------------| | +3VLP | Always-on RTC | Battery/DC | SIO_RTC | | +3V_L | Deep Sleep | Linear Reg (PU201) | +3V_L -> EC_VCC | | +5V_ALW | Always on 5V | PU401 (TPS51285) | +5V_ALW -> +3V_ALW | | +3V_ALW | Always on 3V | PU402 (RT8239A) | EC_PWRBTN# | | +VDD_CORE | Vcore CPU | PU501 (RT8239B) | VR_READY | | +VDD_SOC | SoC/GPU | PU601 (SY8288) | ALL_SYS_PWRGD |
Key power-on signal: PM_RSMRST# (SIO pin 128) → PWRBTN# (SIO pin 64) → PM_PWRBTN# to CPU.
The "LA" prefix denotes a Compal motherboard design. The full identifier "LA-E791P" is silkscreened directly onto the PCB next to the RAM slots. The "Rev 2.0" is critical; Dell and Compal often release multiple revisions (Rev 1.0, 2.0, 3.0) with different component placements, resistor values, and IC pinouts. Using a Rev 1.0 schematic on a Rev 2.0 board will result in misdiagnosis.
As a repair professional, you need verified, virus-free files. While we cannot host direct files here due to copyright, you can find the LA-E791P Rev 2.0 schematic on legitimate technician forums and repositories such as:
Warning: Avoid random "free download" sites on Google that claim to have the PDF but host executable files. Always check file extensions; you want a .PDF for the schematic and .CAD or .BRD for the boardview.
Rev 1.0 of the La-e791p faced challenges like power inefficiency, signal integrity issues, and limited I/O capabilities. Rev 2.0 tackles these issues with:
This is proprietary technical data owned by Lenovo/Compal (the ODM). It is not officially available to the public. Technicians usually acquire these through the following methods:
Important: Be careful when downloading .pdf or .dz (BoardView) files from forums. Always scan files with an antivirus before opening.
Unlike consumer block diagrams, the La-e791p Rev 2.0 schematic uses net labels and cross-references. Example:
Use a PDF viewer with search and layer toggling if available. Many repair communities provide boardviews (.BRD) alongside the schematic, allowing component location on the physical PCB.
Almost every schematic starts with a Block Diagram.