Troubleshooting RSMRST# on the LA 9104

In this professional motherboard repair training video, we dive deep into the S5 standby sequence and explain the critical RSMRST# (Resume Reset) signal using real board images and schematic analysis for the Dell Inspiron 3521 (LA-9104P motherboard) . What You Will Learn: What RSMRST# means: It acts as the "permission signal" allowing the PCH to wake up . Why RSMRST# is critical: Without it, the PCH stays in reset, the power button appears dead, and the startup sequence halts . Component Relationships: How the Embedded Controller (EC) checks standby conditions (like RTC validity) before releasing RSMRST# to the PCH . Typical Voltage Levels: A healthy RSMRST# should measure approximately 3.3V; if it measures 0V, the sequence stops . Real Troubleshooting Workflow: How to properly verify the power sequence rather than immediately flashing the BIOS or replacing major components like the CPU or PCH . LA-9104P Power Sequence Flow: 19V Adapter ➔ 3VALW ➔ 5VALW ➔ EC Power ➔ RTC Valid ➔ RSMRST# Release ➔ Power Button Accepted ➔ SLP_S5# ➔ SLP_S3# ➔ PLTRST# ➔ CPU VCORE ➔ POST ➔ Display Important Tech Tip: Whenever 19V, 3VALW, and 5VALW are present but the board is dead, make sure to check RSMRST# before replacing any components! You can measure this directly at the PCH-side pullup resistor, on the EC side, or at a connected test point . -------------------------------------------------------------------------------- Need help with motherboard repair? Upload your schematic, boardview, or motherboard photos to Aries Schematic AI https://chatgpt.com/g/g-6a14024d28ec8... and ask your repair questions. Aries Schematic AI helps technicians with: • No Power • No Display • No Charging • Short Circuit • BIOS Problems • Power Sequence Troubleshooting • Signal Tracing • Schematic Analysis Link is available in the video description. Created by Harshad Patel Aries Computer Solutions For AI-powered motherboard troubleshooting: Upload your schematic to Aries Schematic AI on ChatGPT.