This article documents a third and fourth failure of a 24W LED oyster. The luminaire was purchased complete on eBay for about $45.
About 12 months after the last driver replacement, the driver has again failed. Again it is the mains filter capacitor that has failed.
The driver was replaced with the same type, we will see how long it lasts.
Within a few days of replacing the driver, the lamp failed again. This time it was the LED plate.
The LED plate is a 48S2P configuration of 0.5W 5730 LEDs. The fail either as short circuit or open circuit. If one fails short circuit the plate keeps working just two LEDs are dark. If one fails open circuit, its pair will overheat and go open circuit then the whole plate is dark.
A test with a LED tester above quickly identified two LEDs that were open circuit.
A PTC heater plate like the one above was used to solder and unsolder the LEDs. (Mine had those screws replaced with countersunk screws.) The LED plate section carrying the faulty LEDs was placed over the middle of the heater plate, and in about 10s the bad LEDs can be lifted off with tweezers.
Some little dabs of solder paste onto the track lands, and then the new LEDs are placed with tweezers observing polarity. The LEDs have a clipped corner which is not so easy to see, I use the location of the middle pad (2) which is offset towards the anode end. Then hold the plate down on the heater pad until you see the silver of molten solder at the terminals of the LED… takes perhaps 5s or so. Don’t subject the plate to sudden acceleration forces before the solder has solidified as it will dislodge one to many LEDs… depending on how many were over the heater pad.
It has been working for some weeks now, it is only a matter of time before it fails again… weeks or years. This luminaire gets over 12h use per day, >4000h per year, so it is a high use luminaire. MTBF is well less than 10,000h, perhaps around 5000h.
The reason for repairing it on each failure is to understand the reason for the failures.
Conclusions
As previously noted, the operating temperature is quite high, more so in the warmer months. The mains filter capacitor is the most common failure, and though I have replaced them to prove that, I now replace the whole driver board… and they are getting more expensive, especially considering they only last one to two years. Part of the green fraud of LED lighting.
LED failures are less common on these LED plates… but a more difficult repair than driver replacement.
I have studied failure of LED lighting over 10 years or so, and just like the Compact Fluorescent Lights before them, they just do not live up to claims of life, efficiency, cost effectiveness. Post mortem analysis informs that conclusion.
Don’t get me wrong, I like LED lighting except that it is not much more reliable than late production CFLs, early CFLs were also a green fraud… no all of them were!