I bought 10 Thomas Watt LED bulbs and 8 are dead in less than a year (each last about 2-3 months). Soometimes a couple of days before they stop working, they flicker when I switch them on or after they are warm.
I have open some of the bulbs and for some of them, I saw a little black dot on one or two LEDs. I removed the LEDs and solder the connections (cf the picture). After this repair, the LED bulb works for a while and then stop working again.
On a forum someone having similar LED light bulb wrote that the LEDs get twice the current that they are supposed to get. Is this my problem? How can I solve this?
On the "SMD side" of the PCB:
- DB1 (right) is a brigde rectifier (MB10F)
- DS1 (top left) is apparently a Fast / Ultrafast Diode (ES1J)
- the resistor: RS1 (1045)= 10.1mΩ, RS2 and 3 (4870) = 487Ω, RS4(514) = 510kΩ
On the "DIP side" of the PCB:
- U1= 51LP F45
Answer
You probably have this IC:
https://pl.mouser.com/datasheet/2/268/20005311A-1021742.pdf
https://datasheet.lcsc.com/szlcsc/KIWI-KP1051CLPA_C261508.pdf
http://www.chimicron.com/datasheet/maxic/MT7822.pdf
Or something similar one but it does not matter much because it fit your PCB arrangement.
As you can see from it the LED peak current is set by parallel connected \$R_{S2}, R_{S3}\$ resistors.
And this current will probably be equal to \$I_{LED} \approx \frac{0.6V}{2.35\Omega} \approx 250\textrm{mA}\$
https://www.chimicron-en.com/
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