How To Fix LED Bulb
One evening, when I returned home from a call, I switched on the night light in my room; however, it failed to light up and instead began emitting a crackling noise. The moment I heard the noise, I immediately switched it off. I then turned on the main light, put away my belongings, and went to freshen up. After dinner, I took the bulb to my workbench to troubleshoot the fault.
Bulb is of MCPCB type,5w with 6400 color temperature Rating.
For inspection I just pulled off top Dome.
It was repaired earlier, I bypassed the faulty LED; I don’t remember exactly when. I searched my Article & found it here is the link https://jestineyong.com/led-bulb-repaired-2/ it was in 2024, it last almost 1.8 Years.
Pulled off PCB from the bulb by pulling out two Clips from Holder connector side of the bulb.
For confirming noise of crackling, I connected the bulb on mains.
& I Found crackling noise is because of the Sparking on the PCB. This is “capacitive dropper” type power supply without any current control IC. It was very difficult to take this photo. for capturing this sparking light moment because it continuous Blinking with spark noise.
Made of one Dropping Capacitor Class X2 ,3nos- Resistors, 4nos. Diode & one electrolytic capacitor.
Sparking location looks like some oxidation, scrapped the traces using blade & again connected the PCB on mains & turned on & Checked O/p Voltages on PCB. this time no sparking but bulb was not light up…this time I decided to find faulty LED on live power.
Meter shows 288v DC. Voltage should drop down when load is connected but here voltage not dropping because open Circuit on Load PCB.
(Please do not try if you non- Technical Person Doing DIY or are not aware of secure way).
I took an insulated tweezers and started searching for the faulty LEDs one by one; when I shorted out a defective LED, the entire unit lit up. So here I found the culprit.
So here I found the culprit. But wait, the bulb suddenly goes off, may be tweezer get miss contact, I tried again but no success. I disconnected the unit from the power & inspected the LED unit by close look & I found one more LED is fused having burn mark on it. This indicates LEDs are degraded.
Above picture showing the first LED was found bad while testing & nearby next LED is suddenly burned having black spot in middle. So there is no sense to repair it further if not having same type & rating Bulbs for replacement. Hence decided to replace the Bulb PCB to DOB having driver circuit on board. (old Bad PCB is MCPCB Type which required external LED Driver supply). So I took one 9W DOB from my spare collection.
While Replacing the DOB keep always in mind to apply proper thermal paste & heatsink because DOB is porn to overheat than MCPCB.
New DOB Details:
Finally connected New DOB in the bulb casing.
After assembling everything back & putt the bulb on wall Bulb holder & powered it works fine.
Note: what I observed, there is brightness difference in DOB Vs MCPCB, here in this case MCPCB was of 5w & I replaced DOB with 9w, it lights up with the same brightness intensity.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles on CIRCA BP Monitoring Machine Error 3
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