Learn Fault Tracing in IC with Mobile Schematic Diagram — Part 2

When a smartphone will not charge properly, the charging IC is only one part of the investigation. This guide shows mobile-repair learners how to use schematics, IC datasheets, and circuit readings together to trace faults methodically—rather than treating a suspected component as the answer before testing the surrounding circuit.

Part 2 concentrates on IC circuits, with particular attention to charging and battery-monitoring functions. Its explanations connect circuit diagrams to the practical checks a technician can make on a phone’s board.

Read the circuit before testing the chip

The book introduces the role of mobile schematics and IC datasheets in fault tracing. It explains how block diagrams and pin information can help a reader understand an IC’s function and follow the relevant circuit lines. That context gives voltage and resistance readings a clearer purpose: they can be compared with the circuit’s expected operation rather than viewed in isolation.

Follow the charging circuit 🔧

A substantial part of the guide focuses on BQ charging IC functionality and related charging symptoms, including fake or slow charging, overheating during charging, a battery percentage that does not increase, and a device that will not power on. It also discusses the fuel-gauge IC’s role in reporting battery information, such as charging status and temperature, to the CPU.

Use readings to narrow the fault

Ground-resistance readings, digital-multimeter checks, and voltage test points are presented as tools for tracing a problem through the circuit. The book also points to components around the IC that may need consideration, helping readers look beyond the chip itself when diagnosing a fault.

Battery connections matter, too

The contents extend the investigation to battery-connector lines, including BATT ID and BATT THERM, and discuss associated problems and troubleshooting. These sections complement the charging-circuit material by bringing connected signals and components into the diagnostic picture.

A useful reference for repair learners

With its emphasis on schematics, datasheets, block diagrams, and meter readings, this guide is suited to people learning smartphone hardware repair as well as technicians reviewing a structured approach to IC fault tracing. For any specific handset, use the matching device schematic and component datasheet when interpreting measurements.