La-f952p Rev 1.0 Boardview ❲720p❳

Use your boardview software to locate the following test points, inductors (coils), and ICs: Main Power Input Rail ( +19V / +DC_IN ) Near the DC jack input connector.

The board ID corresponds to the Lenovo ThinkPad X390 and X395 series, as well as the T490s in certain configurations. It represents Lenovo’s transition to the "s" series lightweight chassis becoming the standard for business portability.

Launch OpenBoardView and use (or click File → Open) to load your boardview file. la-f952p rev 1.0 boardview

| Symptom | Suspect Component(s) | Proposed Solution(s) | Real-World Example | | :--- | :--- | :--- | :--- | | | Charging circuit (ISL88739A), Input MOSFETs (PQ306) | Check for +19V at the DC jack, then trace to the charger IC. Replace any blown MOSFET or the charging IC. Verify the charging IC's enable signals. | A client replaced a keyboard, losing the insulating layer, which shorted PC302 and PQ306, and blew the ISL88739A charger. Replacing these restored power. | | Random freezes, screen glitches | Faulty system RAM, GPU-related component | Run thorough memory diagnostics (e.g., MemTest86). If the issue persists, use the boardview to locate the GPU power management ICs and related capacitors. Visually inspect for swollen or leaking components. | A user with an oxidized board (maybe from water damage) experienced a 1-second power-on then shutdown, and the problem was never fully diagnosed, possibly due to multiple component failures. | | No display, but backlight works | EDP cable, LCD panel, LVDS circuit | This often points to a lack of image data reaching the screen. Measure the EDP lanes for voltage and clock signals. If they are present, the problem is likely the LCD panel or its cable. If they are absent, trace back to the GPU or its power management. | A forum post about a "no image" symptom mentioned that the voltage on the EDP (embedded DisplayPort) pairs was the same, which could indicate a missing data signal or a fault further down the line. | | Battery not charging, laptop runs on AC only | Battery connection, ISL88739A charger IC | First, check the physical battery connector for damage or poor contact. Test the battery in another laptop or test a known-good battery in the target machine. If that fails, the charger IC is the main suspect. | A common report: "The laptop works fine, but it won't charge the battery." Replacing the ISL88739A IC often resolves the issue. |

Having both the and boardview file readily available on your diagnostic computer will save hours of guesswork, turning blind component swapping into a precise, calculated repair. Use your boardview software to locate the following

Technicians working on this specific motherboard design frequently encounter a few recurring hardware vulnerabilities: A. Short Circuit on the Primary +B+ Rail

: Locate the primary DC-in MOSFETs ( PQ prefix) near the charging port connector. Use the boardview to track the +19V main power rail (often labeled +19V_VIN or B+ ) to check if a decoupling ceramic capacitor ( PC prefix) has shorted to ground. 2. Charging and Power Sequence Failures Launch OpenBoardView and use (or click File →

| Component | Role / Why Important | | :--- | :--- | | | These ICs generate the various voltage rails (e.g., +3V, +5V, +VCC_CORE). The SY8286BRAC is specifically responsible for generating the +3V rail for the PCH and other low-power components. | | Power Inductors (PL404, PL402) | These work in conjunction with the PWM controllers to filter the output voltage. A shorted PL404 or PL402 often indicates a shorted capacitor or a short on the output side of the power rail. | | Capacitors (e.g., PC302) | These are used for filtering and decoupling. A shorted ceramic capacitor on a power rail (especially the CPU or GPU core voltage) is a common cause of a "no power" or "shuts down immediately" issue. |