1, Power system malfunction
The power supply is the core power source of LED linear lamps, and its stability directly affects the normal operation of the lamps. Power failures can be divided into three categories: input terminal abnormalities, output terminal failures, and triggering of protection mechanisms.
Input power supply issue
Voltage fluctuation: LED linear lights are usually designed with a wide voltage input (such as AC100-277V), but when the voltage fluctuation exceeds ± 15%, the driving power supply may activate overvoltage/undervoltage protection. For example, in industrial electricity scenarios, the start stop of large equipment may cause instantaneous voltage drop in the power grid, leading to the extinguishing of lighting fixtures.
Line break: Loose wiring terminals, damaged wires, or poor switch contact can all cause current interruption. Use a multimeter to measure the input voltage. If the voltage is normal but the light fixture does not light up, it is necessary to check the wiring points carefully.
Polarity reversal: Some driving power supplies are designed as non isolated, and if the input L/N line is reversed, it may cause damage to the internal circuit. Strictly follow the wiring labels in the product manual.
Driver power failure
Electrolytic capacitor bulge: The electrolytic capacitor in the driving power supply is prone to aging and failure in high temperature environments, manifested as a decrease in capacity or leakage. For example, when the ambient temperature exceeds 60 ℃, the lifespan of the capacitor may be shortened to one-third of its nominal value.
IC chip burnout: Overcurrent, overvoltage, or lightning surge may cause damage to the PWM control chip. Preliminary judgment can be made by observing whether there are burn marks on the power supply casing and smelling for any odor.
Transformer short circuit: The insulation damage of the transformer winding of the flyback drive power supply can cause a short circuit, manifested as severe heating of the power supply and no output. LCR bridge is required to measure the inductance of the transformer and compare it with the nominal value.
Protection mechanism triggered
Over temperature protection: When the internal temperature of the lamp exceeds 85 ℃, the driving power supply may activate thermal protection. It is necessary to check whether the heat dissipation aluminum profile has accumulated dust, whether the heat dissipation paste has dried up, or whether the installation spacing of the lighting fixtures is too small.
Short circuit protection: If there is a short circuit between LED chips, the driving power supply will cut off the output. Short circuit points can be located through segmented troubleshooting: disassemble the lamp body and measure the forward and reverse resistance of each section of the lamp strip using a multimeter diode.
2, Damaged light source component
As the luminous core, the failure mode of LED beads directly affects the lighting effect. Common faults include dead lights, light decay, and color temperature drift.
Single or multiple LED beads fail
Electrostatic breakdown: LED chips are sensitive to static electricity, and not wearing an anti-static wristband during production or installation may cause damage to the PN junction inside the chip. It is possible to observe whether there are cracks or black spots on the surface of the lamp bead through a microscope.
Overcurrent burnout: If the output current of the driving power supply exceeds the rated value of the lamp bead (such as the rated current of 3030 lamp bead is usually 300mA), it will cause the gold wire to melt or the chip to carbonize. Use a constant current source to test the lamp beads separately and observe whether they emit light.
Encapsulation defect: The silicone encapsulation layer of inferior lamp beads may have pores, causing water vapor to penetrate and trigger vulcanization reaction, resulting in blackening of the lamp beads. This type of malfunction is more common in humid coastal environments.
Overall malfunction of the light strip
FPC/PCB open circuit: The FPC substrate of flexible light strips may experience copper foil breakage during frequent bending, while the solder pads of aluminum substrate light strips may detach due to thermal stress. The continuity of the circuit can be detected by visual inspection or the on/off range of a multimeter.
Gold finger oxidation: If the connection terminal between the light strip and the driving power supply is exposed to a humid environment for a long time, the contact resistance will increase, leading to heat generation. Use sandpaper to polish the oxide layer and apply conductive paste.
3, Installation and wiring issues
Incorrect installation methods or wiring operations are common human factors that cause lighting fixtures to not light up.
wiring error
Reverse connection of neutral wire: Although LED lights are not sensitive to polarity, if the driving power supply has a built-in lightning protection module, reverse connection may cause module failure. Use a phase detector to confirm the correctness of the wiring.
Parallel quantity exceeding limit: The output power of a single drive power supply is limited. If there are too many parallel light strips (such as a 100W power supply carrying more than 8 meters of light strips), it will cause the output voltage to drop. Calculate the load power according to the product specifications.
Waterproof joint failure: If the waterproof joint of outdoor lighting fixtures is not tightened, rainwater infiltration can cause a short circuit. The joint needs to be disassembled and reassembled, and waterproof glue needs to be injected.
Inappropriate installation environment
Space sealed: Installing linear lamps in light boxes without ventilation holes will trigger over temperature protection if heat cannot be dissipated. At least 5cm of heat dissipation gap needs to be reserved.
Chemical corrosion: Acid and alkali gases in the factory workshop may corrode the metal parts of the lamp body, leading to poor contact. Luminaires with a protection level of IP65 or higher should be selected and regularly cleaned.
4, Abnormal control system
Intelligent LED linear lamps rely on control signals to achieve dimming and color adjustment functions, and signal transmission failures can cause the lamps to fail to respond.
Signal transmission interruption
DMX512 bus fault: If using DMX control, it is necessary to check whether the terminal resistor is installed (120 Ω) and whether the signal line uses twisted pair shielded wire.
Wireless signal interference: Wi Fi and Bluetooth devices in the 2.4GHz frequency band may interfere with ZigBee or LoRa control signals. Need to adjust the channel or add signal repeaters.
Program conflict: When multiple control systems (such as smart switches+APP) simultaneously control lighting fixtures, it may cause command conflicts. Unified access control or priority setting is required.
Dimmer not compatible
Cutting edge phase dimming: Traditional thyristor dimmers may flicker or fail to turn off when they do not match the LED driving power supply. Special LED dimmer (such as 0-10V, DALI) should be selected.
Insufficient dimming depth: The minimum output current of some driving power supplies is too high (such as 10%), resulting in visible dimming to low brightness. You need to choose a product that supports 1% -100% dimming depth.
5, Environmental and aging factors
During long-term use, environmental factors and material aging will gradually reduce the reliability of lighting fixtures.
natural aging
Light attenuation: The luminous flux of LED chips decays over time, and the national standard requires a light attenuation of ≤ 3% after 3000 hours. If the lamp is used for more than 50000 hours, the light attenuation may exceed 30%.
Capacitor failure: The lifespan of electrolytic capacitors in the driving power supply follows the "10 ℃ rule", which means that for every 10 ℃ increase in ambient temperature, the lifespan is halved. Aging power supplies need to be replaced regularly.
Sudden environmental incidents
Lightning surge: Lamps without SPD (Surge Protective Device) installed are prone to breakdown during thunderstorms. T1 level surge protectors need to be installed in the distribution box.
Mechanical impact: Collisions during transportation or installation may cause detachment of the lamp beads. Vibration testing (such as sine wave 10-55Hz, 1G acceleration) is required to verify the reliability of the structure.
6, Troubleshooting and Maintenance Process
Visual inspection: Observe whether the lamp body is damaged or burnt, and whether the wiring terminals are loose.
Voltage measurement: Use a multimeter to measure the input/output voltage and confirm if the power supply is working properly.
Segmented isolation: Disconnect some light strips or power outputs to locate the faulty section.
Replacement test: Replace the suspected faulty component with a known normal power supply or light strip.
Data recording: Establish fault files, identify high-risk problem types, and optimize procurement and maintenance strategies.
