Amplifier repairing course

Lesson 1 • Amplifier Classes and Topologies

Distinguishes Class A, B, AB, D, and G/H designs by efficiency and distortion profile. Connects topology knowledge to expected failure modes in each class.

Lesson 2 • Signal Flow and Gain Stages

Traces audio signal from input jack through preamp, tone, and power stages to speaker output. Understanding signal flow directs systematic fault tracing.

Lesson 3 • Reading Schematics and Datasheets

Teaches schematic symbol recognition, net tracing, and datasheet parameter extraction. Accurate schematic reading is prerequisite for every repair task ahead.

Lesson 4 • Basic Electronics Review

Covers voltage, current, resistance, and power relationships essential for amplifier diagnosis. Establishes the electrical foundation all subsequent repair work depends on.

Lesson 1 • Electrical Safety Essentials

Covers lethal voltage hazards, stored charge in capacitors, and lockout procedures. Safety protocols established here apply throughout every hands-on chapter.

Lesson 2 • Test and Measurement Equipment

Introduces multimeters, oscilloscopes, signal generators, and dummy loads for amplifier testing. Correct instrument use is foundational to accurate diagnosis.

Lesson 3 • Essential Hand and Bench Tools

Identifies screwdrivers, pliers, desoldering tools, and component testers required for repair. Proper tool selection reduces component damage and repair time.

Lesson 1 • Component-Level Fault Confirmation

Verifies suspected components with in-circuit and out-of-circuit resistance, capacitance, and transistor tests. Confirmation prevents unnecessary part replacement.

Lesson 2 • Signal Injection and Tracing

Uses signal generator injection and oscilloscope tracing to locate the stage where signal is lost or distorted. Injection tracing is the fastest method for multi-stage faults.

Lesson 3 • Static and Dynamic Voltage Measurements

Covers DC bias measurements at rest and AC signal measurements under drive conditions. Comparing measured values to schematic references pinpoints faulty stages.

Lesson 4 • Visual and Mechanical Inspection

Teaches burn marks, bulged capacitors, cracked solder joints, and mechanical damage identification. Visual inspection often reveals the fault before any instrument is used.

Lesson 1 • PCB Trace and Pad Repair

Repairs lifted pads, broken traces, and damaged vias using conductive epoxy and jumper wires. Board repair skills recover amplifiers that would otherwise be scrapped.

Lesson 2 • Desoldering and Component Extraction

Teaches pump, wick, and hot-air desoldering for safe component removal without board damage. Proper extraction preserves pads for reliable replacement component installation.

Lesson 3 • Post-Rework Inspection and Testing

Uses visual inspection, continuity testing, and powered verification to confirm rework quality. Systematic post-rework checks prevent repeat failures and customer returns.

Lesson 4 • Surface-Mount Component Rework

Addresses SMD resistor, capacitor, and IC rework using hot-air station and fine-tip iron. SMD rework skills are essential for modern Class D and digital amplifier repair.

Lesson 1 • Power Supply Fundamentals

Reviews rectification, filtering, and regulation stages that produce amplifier supply rails. Understanding supply architecture is prerequisite for supply fault diagnosis.

Lesson 2 • Switching Power Supply Troubleshooting

Addresses SMPS startup faults, PWM controller failures, and snubber circuit issues in modern amplifiers. SMPS repair requires oscilloscope skills developed in earlier chapters.

Lesson 3 • Rectifier and Filter Capacitor Replacement

Covers diode bridge testing, capacitor ESR evaluation, and safe high-capacitance replacement. Correct capacitor selection restores supply stability and extends amplifier life.

Lesson 4 • Voltage Regulator Repair

Tests three-terminal and adjustable regulators, replaces failed devices, and verifies output. Regulator repair restores stable bias voltages for preamp and driver stages.

Lesson 1 • Noise and Hum in Preamp Stages

Identifies ground loops, decoupling capacitor failures, and noisy transistors as hum and noise sources. Preamp noise is amplified by subsequent stages, making early-stage repair critical.

Lesson 2 • Tone Control Network Diagnosis

Tests passive and active tone control networks for frequency response deviations using a sweep generator. Tone faults are isolated by comparing measured response curves to design specs.

Lesson 3 • Preamp Stage Circuit Analysis

Analyses common-emitter and op-amp preamp topologies for gain, bandwidth, and bias conditions. Stage analysis guides targeted component testing rather than random substitution.

Lesson 4 • Input Selector and Switching Faults

Diagnoses dirty rotary switches, relay contacts, and jack socket failures causing intermittent or no input. Mechanical faults in selectors are frequently misdiagnosed as active-stage failures.

Lesson 1 • Driver and Predrive Stage Repair

Diagnoses driver transistors and resistors that control output device switching and current delivery. Driver faults often destroy output transistors if not repaired first.

Lesson 2 • Bias Circuit Adjustment and Thermal Tracking

Adjusts Vbe multiplier or bias trimmer to set correct quiescent current and verifies thermal tracking. Incorrect bias causes crossover distortion or thermal runaway.

Lesson 3 • Output Stage Topology Review

Revisits complementary push-pull, Darlington, and MOSFET output configurations at component level. Topology knowledge determines correct replacement device selection and bias procedure.

Lesson 4 • Protection Circuit Diagnosis and Repair

Tests speaker protection relays, DC offset detectors, and current-limiting circuits that guard speakers. Protection faults cause silent output or unprotected speaker damage.

Lesson 1 • Noise Floor and Hum Measurement

Quantifies residual noise and hum at the output with input shorted using an oscilloscope. Noise floor results validate preamp and power supply repairs completed in earlier chapters.

Lesson 2 • Power Output and Distortion Measurement

Measures rated power output into a dummy load and THD using an oscilloscope or distortion analyser. Power and distortion results confirm the output stage repair meets original specifications.

Lesson 3 • Frequency Response and Bandwidth Testing

Sweeps the amplifier from 20 Hz to 20 kHz and plots response deviation from flat. Bandwidth testing reveals remaining tone-stage or feedback-loop issues after repair.

Lesson 4 • Bench Test Procedure Development

Builds a repeatable test sequence covering power, bias, noise, and frequency response checks. A documented procedure ensures no performance parameter is overlooked before delivery.