Electronic Repair: Learn How to Test Electronic Components

Learn to test voltage regulators, including 78xx series such as 7812, with a multimeter, without power, and verify input, ground, and output continuity.

Test transformers with a multimeter to identify primary and secondary windings and verify correct connections. Check continuity to confirm two separate primary inductors and all secondary terminals connected.

Learn to test optocouplers with a multimeter, verifying four-pin and six-pin devices by checking anode-to-cathode diodes and collector-to-emitter transistors, ensuring no shorts.

Learn to test relays with a multimeter by identifying the four terminals (two inductor, two switch), energizing the coil with 12 volt to close the switch, and checking resistance.

Learn to test bridge rectifiers with a multimeter in diode mode, verify four pins and correct polarity, and test diodes individually to confirm good rectifiers.

Learn to test Schottky diodes with a multimeter, differentiate them from standard diodes, and identify low forward voltage drops on flyback power supplies and heatsinked components.

Test dc motors and windings with a multimeter, checking for low resistance between positive and negative terminals. Power with a 5-volt dc adapter to observe rotor rotation and polarity effects.

Learn how to test transistors used in amplifiers with a multimeter diode test, identify base, collector, and emitter, and use the base-emitter versus base-collector rule to evaluate a transistor.

Test a triac with a multimeter, identify its three pins, verify continuity between gate and pin 1 or pin 3 at about 0.6-0.7 volts, and use a heatsink.

Test switches and SMD and THT buttons using a multimeter to check continuity between ground and the 3.3 volt rail, and verify button operation with the buzzer.

Learn to test diodes with a multimeter, identifying cathode and anode, and checking normal, zener, smd, and bridge rectifier diodes by reading forward voltages and swapping probes.

Learn how to test inductors on a laptop motherboard with a multimeter, using continuity and low resistance checks to confirm a good coil.

Learn to identify and test current sense resistors, typically near the power jack or battery connector, using a low-range multimeter or diode test to verify 0.02 ohms.

Learn to test n-channel and p-channel MOSFETs with a multimeter by checking drain-to-source continuity, swapping probes to verify reading patterns, and identifying bad MOSFETs on real boards.

Learn how to test light emitting diodes on laptop motherboards using a multimeter, checking the cathode and anode with color indicator lights to verify operation.

Learn to test electrolytic capacitors with a multimeter, identify polarization, and verify no continuity to distinguish good capacitors near the chipset and in power supplies.

Learn to test circuit continuity with a multimeter, trace component paths, and assess cable serviceability by checking zero resistance along connected points.

Test ceramic and pF capacitors on a laptop motherboard with a multimeter in continuity mode, checking high resistance on good capacitors and distinguishing low resistance in chipsets from shorts.

Learn how to test integrated circuits (ICs) on a laptop motherboard using three methods: heat check with a finger, verify input/output signals, and inspect surrounding ceramic capacitors for shorts.

Learn how diodes work and how to test them with a multimeter using the diode, buzzer, or continuity setting, reading 0.695–0.700 volts in forward direction and no reading when reversed.

Learn how to test zener diodes with a multimeter, identify cathode and anode, and verify good diodes using diode and continuity tests across surface mount and through-hole types.

Test smd diodes on a laptop motherboard with a multimeter in buzzer mode; verify polarity with red on positive and black on negative, noting readings around 600–700 for good diodes.

Learn how to identify eight-pin MOSFETs, distinguish source, gate, and drain pins, and test them with a multimeter using continuity and diode checks to verify proper isolation and operation.

Learn how to test motherboard MOSFETs with a multimeter, identify source and drain pins, and interpret resistance readings to distinguish shorted from normal circuitry.