Optonica 20 Watt LED Bar 4000K Repair
Recently another good friend brought his now defect Optonica led light bar. It was almost brandnew and already defect after only about 10 months of use. And because his warranty period was still good he already got a new replacement led bar why he gave me his now defect led bar.
Both caps on each end of this led bar have a connector to input 230VAC to all 100 leds. Which also makes it possible to easily connect another led bar to this one. There is also a small tumble powerswitch on the side of the bar.
Both wires were first unsoldered so the led stripe board could be shifted and pulled out of the round holder bar. And after prying out the mini tumble switch I also was able to extract a small power regulator board that was hidden under the led board inside the housing. More on that later.
After the ledstripe was extracted the first leds that were suspected to be bad showed black spots on top of them. And they indeed were defect including 7 other leds without any black spot marks.
And they all showed a very low voltage when I tested them with my handy led tester. And obviously none of those leds did work anymore.
Below LED TV Backlight tester is great in finding the bad leds and can also be used to safely test small smps power adapters on the 230VAC as I already wrote about in an older article on this blog.
Below photo shows the max test voltage when connected to the 230VAC input of the led bar after it is completely fixed. And the photo after that shows the working led bar connected to the TV backlight tester.
Because of the regulator power board that is connected inbetween the led stripe and the 230VAC input, the with my TV backlight tester measured operating voltage and here shown leds current deviates from the real values when the led bar is directly fed from the power line. Also giving light more brightly.
In total 9 leds were replaced. Below are the replacement SMD2835 leds shown that are used to replace the bad leds. 100 of them are about 1.67 euro/dollar free shipping. I only had warm white 3200 Kelvin leds in stock, but did order NATURAL WHITE 4000 kelvin 2835 leds that originally were used in this led bar according to the label.
Below photos show the stripe with 100 leds, and the 230VAC through both ends wiring.
Next photos show the cheap hot plate with a 230VAC PTC element that I used to easily remove the bad leds from the stripe. Both top and bottom plate are shown here.
This in the past cheap Aliexpress bought hot plate gets hot in seconds and takes a long time to cool off!
And here follows the more interesting part of this repair after removing and examining the earlier mentioned power voltage regulator board that is also hidden in the bar housing. That board carries a DP2866A Non-isolated Buck offline led-driver chip. Although searching for that chip resulted in finding the probably identical BP2866A led driver ic instead. That datasheet can be found here:
https://datasheetspdf.com/pdf-file/1258882/BPS/BP2866D/1
The yellow transformer looking part was measured being a 3.76mH coil with my Mastech tweezer tester.
Following photos show all parts more clearly.
Above left photo showed the DP2866A and photo right the diode. Next photo shows the board solder side.
Previous 2 with my portable digital LCD G600 microscope taken snapshots showed both ecaps with 2.2uF 250V and 8.2uF 400V value.
And above snapshots showed the red capacitor being a 400V 100nF value. And the blue 07D471K part must be an overvoltage protecting VDR.
Underneath the above visible red C1 400V 100nF capacitor there most likely is a bridge rectifier placed with board marking DB1. As shown more closely on next board side view photo.
Before I was able to pull out the hidden board with the DP2866A Non-isolated Buck offline led-driver chip I first had to pry out the small tumble switch to get it out of the way.
Following photos show the completely fixed led bar that will be of good use in my electronics shack.
After this successful repair the question remains why these leds go bad in such a short period of time? Something I also noticed in a previous led-staircase-light repair that also did quit working long before a reasonable use of time.
And I therefore do hope that my friends new Optonica replacement led bar doesn’t also suffer the same led problem in time!
Stay safe and always keep in mind that the led bar in this repair is directly connected to the unsafe 230VAC power line!
Until another repair.
Albert van Bemmelen, Weert, The Netherlands.
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14 Comments
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Parasuraman S
May 20, 2023 at 9:33 am
Vow! Information packed and very detailed article! I appreciate your patience in putting every minute detail of your repair work! Many thanks, dear!
Albert van Bemmelen
May 24, 2023 at 8:53 pm
PS: Of the 9 leds I replaced, only one led was still fine! So they are likely placed in sets of 2 leds in series.
Mark
May 20, 2023 at 3:12 pm
Thanks Albert for a well described, detailed, thoughtful diagnosis.
Albert van Bemmelen
May 20, 2023 at 8:54 pm
I used the words 'led stripe' but I probably was wrong as it should be 'led strip' instead? I get confused with the name Meryl 'Streep' which is 'streep' in Dutch which again is 'Strip' in English. But also the English Stripe is Dutch for Streep.
Maarten
May 21, 2023 at 3:51 pm
Hi Albert,
Nice report!
In my experience, sometimes designers go for the maximum current that a LED can withstand when designing a power supply. I usually leave some headroom so even the 'weakest' LED will operate within its specification.
Did you check the current through the string? Often you can lower the current without noticing any decrease in the light output... (Too bad the datasheet provided does not state how to calculate the current sense resistor at pin 7).
Albert van Bemmelen
May 24, 2023 at 9:01 pm
I only checked the current through all leds with my connected led tester. But specs of the led model SMS2538 given by the manufacturer mention a voltage of DC 3-3.4V at a current of 120mA with dissipated max power of 0.5 Watt each. And with 60 to 65 Lumen(LM).
Albert van Bemmelen
May 24, 2023 at 10:22 pm
Above description of the specs of the brandnew received SMD2835 Cool White and Natural White leds was different and better compared to the shown specs of the previously ordered and in the article used SMD2835 leds.
Albert van Bemmelen
May 25, 2023 at 1:20 am
PS: The bigger resistor on the small powerboard next to the VDR was with code red-red-gold-gold probably a 2.2 ohm 5% resistor but probably just a inrush current limiter resistor or an AC input noise reduction limiter together with the 400V 100nF capacitor. And likely not the resistor that is connected between IC pin 7 and 1 (notice the odd IC pin numbering!).
If the led bar gets defect again another time I will analyse the circuit further but for the moment I'm just glad that the strip was fixed and working.
Albert van Bemmelen
May 27, 2023 at 5:07 pm
Maybe this almost identical led driver chip will give more information on the here used DP2866A:
Waleed Rishmawi
May 23, 2023 at 1:23 pm
a very detailed repair with data sheets provided and highly appreciated. would you give any recommendation on the hot plate you used to desolder the led light off the strip? I have seen that on the net but not sure if it a good one worth having or fake? thanks and have a good blessed day
Albert van Bemmelen
May 24, 2023 at 9:14 pm
The in the article used hotplate worked excellent with the ledstrip in the now fixed ledbar. Because the heat went easily through the top of the thin stripboard. But in the past it hardly worked with those thicker plated copper strips from certain television sets. So for the affordable cheap price in this example it certainly is completely worth the money! Removing the leds is with this hotplate only a matter of seconds!
The 70 x 120 mm version can be found here.
Albert van Bemmelen
May 26, 2023 at 9:47 pm
Although the DP2866A datasheet couldn't be found the chip is easily available on Aliexpress. Here:
Albert van Bemmelen
May 27, 2023 at 5:05 pm
Here is a link to a very similar led driver datasheet that may give more details on how this (D/B)P2866A chip controls the long led bar
Yogesh Panchal
May 27, 2023 at 10:38 pm
Albert,
Good fix! Out of one faulty 20W Batten, I just made two LED batten by eliminating damaged LED Segment & Using 7W LED Driver kit from old salvaged BAD LED Bulb.
i will share the article Shortly.