I. Core Causes Classification
Power Supply Issues (Most Common)
Aging Driver: Electrolytic capacitor degradation reduces capacity (lifespan shortens to 2–3 years in high temperatures), increasing output current ripple.
Power Mismatch: Driver power lower than fixture demand (e.g., 30W driver for 40W light).
Harmonic Interference: Substandard EMC filtering in cheap drivers (THD >30%) causes current fluctuations.
Voltage Fluctuations: Input voltage <90V or >265V (exceeds driver IC operating range).
Dimmer Compatibility
Incorrect Dimmer Type: TRIAC dimmers used with non-dimmable LEDs disrupt phase-cut synchronization.
Insufficient Minimum Load: Traditional dimmers require ≥25W resistive load; LEDs (e.g., 5W) cause flickering.
Signal Interference: EMI disrupts 0–10V/PWM wiring (e.g., parallel high-voltage cables).
Circuit Faults
Loose Connections: Poor terminal crimping (contact resistance >0.5Ω) causes intermittent disconnects.
Live/Neutral Reversal: Switching neutral wires creates voltage potential fluctuations.
Poor Grounding: Ground wire resistance >4Ω induces common-mode noise.
Fixture Defects
LED Gold Wire Fracture: Thermal stress cracks solder joints (common in COB packaging).
Thermal Failure: Junction temperatures >120℃ trigger cyclic overheat protection.
PCB Leakage: Insufficient creepage distance (<3.2mm) causes discharge in humid environments.
II. Diagnostic Workflow (Four-Step Method)
Basic Checks
→ Confirm dimming compatibility ("Dimmable" label).
→ Measure input voltage with multimeter (±10% tolerance).
→ Swap driver with a known-good unit.Waveform Monitoring (Requires Tools)
→ Oscilloscope test: Driver output should be smooth DC (ripple <10%).
→ Analyze TRIAC conduction stability (use FLUKE 1736 power analyzer).Thermal Imaging
→ Scan with infrared camera (e.g., FLIR E5):
▪ Driver >85℃ → Cooling failure.
▪ Localized LED hot spots → Gold wire breakage.Insulation Test
→ Megohmmeter check: Cable insulation >10MΩ.
→ Humidity/IP test (e.g., submersion for IP65 fixtures).
III. Solutions Reference Table
| Fault Type | Solution |
|---|---|
| Capacitor Failure | Replace with 105°C-rated capacitors (e.g., Nichicon PW series; lifespan >8,000h). |
| TRIAC Flickering | Install MLV (magnetic attenuator) or switch to digital dimming (e.g., Lutron Diva DVCL). |
| Voltage Drop | Shorten wiring distance or increase wire gauge (<3V drop per 100m). |
| Overheating | Add aluminum heatsinks (thermal conductivity >5W/mK) or reduce power to 70%. |
| EMI Interference | Install ferrite rings (100Ω @100MHz) or π-filters on power input. |
IV. Preventive Maintenance
Driver Selection:
↑ Reserve 20% power headroom (e.g., 36W driver for 30W fixture).
↑ Prioritize UL Class 2 / IP67 / THD<15% certified units.Installation Protocol:
↑ Use DALI protocol for dimming (bus voltage <30V, EMI-resistant).
↑ Deploy Class II insulated fixtures in damp areas (no grounding needed).Lifespan Management:
↑ Test capacitor ESR every 2 years (normal <0.5Ω).
↑ Replace preemptively per 10°C rule: Halve lifespan for every 10°C >40°C ambient.
⚠️ Industry Alert: Avoid cheap drivers with inflated specs (<60% actual output). Opt for Mean Well, Philips to reduce failure rates by 80%.
🛠️ Unresolved Cases: Check inrush current with oscilloscope (possible NTC thermistor failure) or validate LED-driver IC compatibility (e.g., BJT chips with MOSFET drivers).