Diagnostics guides
Step-by-step fault finding for dead, shorted and half-working laptop boards.
- Diagnostics
Beep and Blink Codes: How to Use Them in Board Diagnosis
How to use beep and blink codes in laptop board diagnosis: what they mean, how to read patterns, where tables come from, POST code cards and what silence tells you.
- Diagnostics
USB-C Laptop Not Charging: PD Controller Diagnosis
How to diagnose a USB-C laptop that will not charge: reading a USB-C meter, CC and VBUS checks, the PD controller and its firmware, sink MOSFETs and the charger IC.
- Diagnostics
Reading Current Draw on a Bench Supply: What the Numbers Tell You
What the current on a bench power supply tells you about a laptop board: zero, standby, stuck and cycling patterns, shorts, and how far the power sequence got.
- Diagnostics
No Backlight on a Laptop Screen: Diagnosis Guide
How to diagnose a laptop screen with an image but no backlight: the flashlight test, backlight power, enable and PWM signals, the lid sensor, fuse and panel checks.
- Diagnostics
Laptop Works Only with the Charger Connected
Why a laptop runs on the charger but dies without it: worn battery, detection faults, the battery MOSFET, charger IC settings and connector damage.
- Diagnostics
Laptop Wi-Fi Card Not Detected: Board-Level Causes
Why a laptop does not detect its Wi-Fi card and how to check it: the M.2 slot, 3.3 V power, PCIe reset and clock, W_DISABLE, BIOS whitelists and soldered modules.
- Diagnostics
Laptop Webcam Not Detected: Board-Level Diagnosis
How to diagnose a laptop webcam that is not detected: privacy switches, BIOS settings, camera power, USB lines, the display cable and the camera module itself.
- Diagnostics
Laptop USB Ports Not Working: Board-Level Checks
How to diagnose dead laptop USB ports at board level: separating power from data, VBUS and its power switch, fuses, ESD arrays, connector damage and USB 3 lanes.
- Diagnostics
Laptop Turns On Then Off Immediately: Causes and Fixes
A laptop that powers on for a second and shuts off is aborting its power-on sequence. How to find which rail or power-good fails, and the usual culprits.
- Diagnostics
Laptop Touchpad Not Working: Board-Level Checks
How to diagnose a laptop touchpad that does not work at board level: settings first, I2C-HID and PS/2, power, flex cable, pull-ups and interrupt.
- Diagnostics
Laptop SSD or NVMe Drive Not Detected: Board-Level Causes
Why a laptop does not detect its SSD or NVMe drive: BIOS storage modes, SATA versus NVMe slots, 3.3 V power, PCIe reset and clock, and how to tell drive from board.
- Diagnostics
Laptop Running Hot at Idle: Motherboard Causes
Why a laptop gets hot while doing nothing: ruling out software, cooling faults, leaky rails, stuck regulators, a GPU that never sleeps, and finding the hot spot.
- Diagnostics
Laptop Random Shutdowns Under Load: Board-Level Causes
Why a laptop shuts down at random under load: overheating, underpowered adapters, weak batteries, regulator protection, and how to tell them apart.
- Diagnostics
Laptop Powers On but No Display: Where to Start
Fans spin but the screen stays black? How to tell a display fault from a no-boot fault, test with an external monitor, and check memory, BIOS and panel circuits.
- Diagnostics
Laptop Power Button Does Nothing: Testing the Switch Circuit
Laptop power button does nothing? How the button circuit works, checking the switch, cable and pull-up, the signal to the EC and chipset, and what else blocks it.
- Diagnostics
Laptop Not Turning On: Step-by-Step Motherboard Diagnosis
A step-by-step method for a laptop that will not turn on: adapter and input, current draw, system rail, always-on rails, EC, power button and the power-on sequence.
- Diagnostics
Laptop Not Detecting the Battery
Why a laptop reports no battery and how to find the cause: pack lockout, connector damage, SMBus pull-ups, thermistor and present pins, the charger IC and EC.
- Diagnostics
Laptop Not Charging: Charging Circuit Diagnosis
How to diagnose a laptop that runs on the adapter but will not charge: battery, adapter ID, charge limits, the charger IC, battery path MOSFETs and SMBus checks.