H-ig41-uatx Rev 1.1 Schematic Verified -

Inside the Foxconn H-IG41-UATX Rev 1.1: A Schematic Analysis

The Foxconn H-IG41-UATX Rev 1.1 is a classic Intel LGA 775 motherboard commonly found in OEM desktop PCs, particularly from HP and Compaq systems (often branded as the Pegatron M2N78-LA or similar variants). For electronics technicians and hobbyists, the schematic diagram for this board is more than just a wiring map—it is the "Rosetta Stone" for diagnosing complex power failures and bringing dead boards back to life.

This article explores the technical architecture of the H-IG41-UATX, breaking down the key sections of its schematic and explaining what repair technicians look for when troubleshooting this hardware.

Revisions in 1.1

• Corrected power sequencing timing margins to address a startup instability found in 1.0.
• Added TVS diodes on USB/PCIe connectors and increased bulk capacitance on 12 V input.
• Clarified footprint for alternate RTC battery and improved silkscreen for front-panel header.
• Minor schematic symbol and netlabel consistency fixes.

I/O, connectors, and headers

• ATX front-panel header: Standard pins for power LED, HDD LED, reset, power switch, and speaker.
• Peripheral connectors: SATA power, front-panel USB (USB2/USB3), audio headers, and fan headers with PWM control and tachometer feedback.
• Expansion and debug: Debug UART header, JTAG/SWD footprint for firmware and silicon debug, and optional mini-PCIe or M.2 outlines depending on board variant.

5. I/O Ports (PS/2, USB, Audio, COM)

Rev 1.1 often has updated ESD protection diodes (e.g., Rclamp0524P). The schematic helps bypass blown data lines. h-ig41-uatx rev 1.1 schematic

1. The Core Architecture: The Intel Bearlake Chipset

To understand the schematic, one must first understand the chipset. The "IG41" in the model name refers to the Intel G41 Express Chipset (codenamed "Bearlake").

• The Northbridge (G41 MCH): This chip handles the fast communication between the CPU, RAM, and the integrated graphics. In the schematic, you will see dense routing for the Front Side Bus (FSB) and the DDR2/DDR3 memory traces.
• The Southbridge (ICH7): This chip manages the slower I/O functions—SATA ports, USB, PCI slots, and audio.

Schematic Significance: When tracing a "no display" issue, the schematic is used to check the PWM (Pulse Width Modulation) signals feeding the Northbridge. Unlike modern processors where the memory controller is inside the CPU, on the G41, the memory controller is inside the Northbridge. If the RAM voltages (VTT) are not correct according to the schematic, the board will not POST. Inside the Foxconn H-IG41-UATX Rev 1

How to Read a Boardview for Rev 1.1

A schematic alone isn't enough. You also need the Boardview file (.cad, .brd, or .fz). Programs like OpenBoardView or LinkerCad allow you to click a net name and see exactly where the trace runs on the physical PCB.

For Rev 1.1, boardview files reveal:

• Test points (TP1, TP2) for voltage measurement.
• Via locations (critical for multi-layer boards).
• Component orientation (polarity of capacitors).

Understanding the Components

• H-IG41: This refers to the chipset used on the motherboard. "H" typically denotes a specific series or type of chipset from Intel, known for their stability and feature set. The "IG41" specifically relates to the Intel G41 Express chipset, which is a part of Intel's chipset family designed for desktops. The G41 chipset supports Intel Core 2 Duo, Core 2 Quad, and Pentium dual-core processors.

• UATX: This seems to refer to the form factor of the motherboard. However, the standard abbreviation for a smaller version of ATX is "mATX" or micro-ATX. Assuming "UATX" might be a typo or specific form factor not widely recognized, it's likely referring to a micro-ATX form factor, which is a common size for motherboards that balances compactness with expandability. Corrected power sequencing timing margins to address a

• Rev 1.1: This indicates the revision of the motherboard design. Revision numbers are used to track changes in hardware design, layout, or component usage.

4. Key Component Locations (Inferred from Rev 1.1 PCB)

• Super I/O: IT8720F-S (Lower right corner, near PCI slots). Monitors voltages and controls PSON#.
• Clock Generator: ICS9LPRS365 (Between CPU socket and PCIe x16 slot).
• Audio Codec: ALC662 (Bottom left, near line-out jacks).
• LAN PHY: RTL8103E or RTL8111DL (Near rear USB ports).
• BIOS ROM: MX25L1605D (8-pin SOIC, near SATA ports). Note: Rev 1.1 uses a 16Mbit SPI flash.