Learn board-level repair
Repair guides — page 2
Practical, bench-tested guides: reading schematics, using boardview software, BIOS programming, power circuits and step-by-step diagnostics. Each guide explains what to measure, in what order and why.
- Reading Schematics
Test Points in Laptop Schematics and How to Use Them
What test points are on a laptop motherboard, how to find them in the schematic and boardview, and how to measure rails and signals safely when no test point exists.
- BIOS
SPI Flash Write Protection and Status Register Bits
SPI flash write protection explained: status register bits BP, TB, SEC, SRP and QE, the WP pin, lock bits, and why a chip that reads fine refuses to erase or write.
- BIOS
Reading SPI Flash Part Numbers: Winbond, Macronix, GigaDevice
How to read SPI flash part numbers from Winbond, Macronix, GigaDevice and others: capacity digits, 1.8 V versus 3.3 V families, package and temperature codes.
- BIOS
SPI Flash Chips Explained: The 25-Series BIOS Memory
How 25-series SPI flash chips work: pinout, capacity from the part number, 3.3 V and 1.8 V families, packages, write protection and what that means for BIOS work.
- BIOS
SOIC8 Clip vs Desoldering: Safe BIOS Chip Programming
When to read a BIOS chip in circuit with a SOIC8 clip and when to desolder it: back-feeding, bus interference, unstable reads and how to remove the chip safely.
- Components
SMD Component Marking Codes: How to Identify Unknown Parts
How to identify unknown SMD parts from their markings: resistor and inductor codes, polarity marks, short transistor codes, IC top marks and datasheets.
- Components
Signs of PCH (Chipset) Failure in Laptops
Signs of a failing PCH (chipset) in a laptop: missing sleep-state signals, shorted chipset rails, dead USB and storage, heat, and how to rule out firmware first.
- Reading Schematics
Schematic Revisions: Why Rev 0.3 vs Rev 1.0 Matters
What schematic and board revisions mean, how Rev 0.x, 1.0 and later differ, how to read the change history page, and when a close revision is good enough.
- Brands
Samsung Laptop Motherboard Codes Explained
How Samsung laptop motherboards are identified: BA41 and BA92 numbers, project names, revisions and NP model numbers, and how to find the right documents.
- Power Circuits
The RTC Circuit and CMOS Battery in Laptops
How the laptop RTC circuit and CMOS battery work: the RTC rail, its diodes and crystal, RTC reset, symptoms of a flat coin cell, and how to measure and fix them.
- Reading Schematics
Reference Designators on Laptop Boards: PU, PQ, PR, PC, PL and More
Reference designators on laptop boards decoded: PU, PQ, PR, PC, PL and other prefixes, how numbers follow schematic pages, arrays, test points and not-fitted parts.
- Reading Schematics
Reading Voltage Regulator Pages in Laptop Schematics
How to read a voltage regulator page in a laptop schematic: controller pins, input and output, enable and power-good, feedback, switching parts and notes.
- Reading Schematics
Reading the USB-C Section of a Laptop Schematic
How to read the USB-C section of a laptop schematic: connector pinout, CC and SBU, PD controller, VBUS sink and source switches, muxes, retimers and Thunderbolt.
- Reading Schematics
How to Read the Memory (DDR) Pages of a Laptop Schematic
How to read the memory pages of a laptop schematic: DDR channels and signal groups, SO-DIMM and soldered memory, SPD, power rails and memory ID straps.
- Reading Schematics
Reading the Display (eDP and LVDS) Section of a Laptop Schematic
How to read the display section of a laptop schematic: eDP lanes, AUX and HPD, LVDS pairs, panel power, backlight signals, EDID and the shared display connector.
- 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.
- Reading Schematics
Pull-Up and Pull-Down Resistors in Laptop Schematics
What pull-up and pull-down resistors do on laptop boards, where they sit on enable, power-good, reset and SMBus lines, and how to fix a signal stuck high or low.
- BIOS
WSON8 BIOS Chips: How to Read and Program Them
How to read and program WSON8 BIOS chips: why clips do not fit, pogo-pin probes and sockets, desoldering the exposed pad safely, and refitting the chip afterwards.