FAQ
TL;DR: Fast LED blinking is usually a bad driver cap; one post estimates “90% is the fault of the electrolytic capacitor.” Replace/load‑test before swapping LEDs. [Elektroda, teskot, post #18320508]
Why it matters: This FAQ helps DIYers diagnose and fix outdoor LED floodlights that blink, flash, or pulse without replacing the whole lamp.
- Typical protection pulsing period: 1–5 seconds when the driver trips, recovers, and repeats. [Elektroda, paul0, post #18321783]
- Open‑circuit measurement example: ~60 V reported on a disconnected LED string. [Elektroda, sebaele22, post #16857118]
- DC bus after mains bridge: Expect over 300 V DC; verify before deeper checks. [Elektroda, zdzichra, post #16857542]
- Always measure the driver under load; no‑load readings can mislead. [Elektroda, paul0, post #18321783]
- First swap candidates: electrolytics at the driver output to cure cycling. [Elektroda, 750kV, post #18320455]
Quick Facts
- Typical protection pulsing period: 1–5 seconds when the driver trips, recovers, and repeats. [Elektroda, paul0, post #18321783]
- Open‑circuit measurement example: ~60 V reported on a disconnected LED string. [Elektroda, sebaele22, post #16857118]
- DC bus after mains bridge: Expect over 300 V DC; verify before deeper checks. [Elektroda, zdzichra, post #16857542]
- Always measure the driver under load; no‑load readings can mislead. [Elektroda, paul0, post #18321783]
- First swap candidates: electrolytics at the driver output to cure cycling. [Elektroda, 750kV, post #18320455]
Why does my LED floodlight blink every two seconds?
That rhythm matches a driver going into protection, then recovering. Many constant‑current supplies pulse every 1–5 seconds when the LED load voltage drifts outside the allowed range. Load‑testing confirms this behavior and separates driver faults from LED faults. [Elektroda, paul0, post #18321783]
How can I tell if the driver or the LED module is bad?
Load the driver with a suitable resistor so the output sits within its rated voltage window. If the voltage stays stable, suspect the LED string or joints. If it still pulses or shuts down, the driver is faulty. “Measurements should be made with the power supply loaded.” [Elektroda, paul0, post #18321783]
What voltage should I see after the bridge rectifier?
Measure the high‑voltage DC bus across the main electrolytic after the bridge. Expect over 300 V DC on 230 V mains. If it is low or heavily rippled, check the bridge and bulk capacitor before anything else. [Elektroda, zdzichra, post #16857542]
Should I measure the driver with the LEDs disconnected?
Avoid no‑load measurements for diagnosis. Many LED drivers behave abnormally when open‑circuit, including pulsing or shutdown. Always test under a realistic load within the driver’s voltage range to get meaningful readings. [Elektroda, paul0, post #18321783]
Which parts fail most often in these blinking lamps?
Electrolytic capacitors are the primary culprits. One experienced repairer reports “90% is the fault of the electrolytic capacitor,” often near a series resistor (e.g., labeled R6). Replace suspect caps first. [Elektroda, teskot, post #18320508]
How do I load‑test the LED driver safely? (3 steps)
- Calculate a power resistor so the driver’s current creates a voltage inside its rated range.
- Connect the resistor and power on briefly; observe if output stabilizes.
- If stable, inspect LEDs/solder; if pulsing or tripping, service the driver. [Elektroda, paul0, post #18321783]
Can damaged LEDs or bad solder cause slow flashing?
Yes. Heat can open micro‑cracks or weak joints, breaking the series string. Cooling restores contact, creating a blink cycle. Look for discolored chips or odd color points along the series chain indicating a failing LED or bridge. [Elektroda, paul0, post #18320418]
Voltage jumps with LEDs connected and disconnected—what does that mean?
A jumping output under load and no‑load points to a failing driver. The control loop cycles because it cannot regulate current. In brief: “The driver is dead.” Replace or repair the supply. [Elektroda, zdzichra, post #16857171]
What should I replace first on a pulsing driver output?
Swap the electrolytic capacitors at the driver output. A leaky or shorting cap can fool the limiter into thinking LED current is nominal, causing shutdown and cycling. Use quality replacements. [Elektroda, 750kV, post #18320455]
What capacitor specs are safe when substituting?
Match or increase capacitance, and use equal or higher voltage rating. A 25 V or greater rating was advised for the small electrolytic near the resistor in this design. [Elektroda, teskot, post #18320912]
What is an LED driver (sometimes called an inverter) in these lamps?
It is a constant‑current power supply with an allowed output voltage range. It regulates LED current; if voltage exceeds or drops below the window, it shuts down or pulses to protect itself and the LEDs. [Elektroda, paul0, post #18321783]
Can I convert a failed mains LED floodlight to 12 V or 24 V use?
Yes. Some users remove the failed driver and run the LED string from a suitable 12 V or 24 V supply. This can repurpose the lamp for vehicles or outbuildings when original electronics are unreliable. [Elektroda, zdzichra, post #16857041]
What if the transformer has an inter‑turn short?
A shorted transformer causes erratic operation and overheating. Repair is difficult without rewinding equipment. In that case, replacing the driver module is the practical fix. [Elektroda, zdzichra, post #16857542]
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