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LED Lamp Repaired

By on December 23, 2015
led lamp repair how to








One of my friends sent me six blown made in China led lamps and asked me why the life span of these lamps were between a week up to few months? I had to open it up to troubleshoot so that I can give him an answer. After opening of the lamps I found in all of them the PCB and other components turned to charcoal due to explosion of electrolyte capacitor. Five LED lamps were badly blown and one was in better condition.

Below are the components found in the circuit board :

1- Smd diode M7

2-Electrolytic cap with 2.2 microfarad 450 volt

3- Transistor MJE 13003

4- Resistor with code of 123 SMD and another one with code 100

6- SMD transistor 3Y =S8050


8- Smps transformer

All above components were installed on the primary side. In secondary side there was just one Smd resistor plus one Schottky diode

led lamp repair

led lamp repairing

As you can see in following picture the big cap was bulgy and exploded

bulgy capacitor

led light repair

how to repair led light

After replacing the electrolytic cap the LED lamp start to work again.

Why these led lamps won’t last long enough?

The minimum requirement for rectification and converting the AC to DC needs at least two diodes (full wave rectifier). Using only one diode (half wave rectifier) will produce a dirty DC and in the long run the filter capacitor will blow. This is not the first time I’m seeing such design in a China made products. If the manufacturer added another diode for rectification (full wave rectifier), I believe the capacitor would have a longer life and will benefit the users and the manufacturer in the long run.

I fully recommend Mr Jestine Yong ebook about SMPS Power supplies repair to all manufacturers and students. If you would like to learn how to troubleshoot and repair of SMPS.






This article was prepared for you by Mr Beh from Iran.

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  1. Albert van Bemmelen

    December 23, 2015 at 5:17 pm

    Thanks Beh for this article! I have seen a lot of defective SL lamps on the inside before but I believe it is my first view on the inside of a led lamp. I heard in the news recently that the manufacturers at least in Europe all Lie on the consumed current and value of given Lux. Being that they use more current and even give less Light. So it is not all bright technology (;-) . Cheers!

    • beh

      December 24, 2015 at 11:02 am

      Hi Albert
      yes on the body of this lamp is written 3 watt consumption of energy but as you told who can prove this ? this needs special equipment and performing the tests .i wished i could give a correct answer to this question.
      thanks for comment

  2. Parasuraman S

    December 24, 2015 at 7:06 am

    Good, descriptive article! Voltage will increase if two diodes are used on both sides of AC input (full wave rectifier). Then you might need more components to reduce it. Moreover, they would have designed the switching and pulse width taking into account the half wave rectified DC. So, probable reason is economy!

    • beh

      December 24, 2015 at 11:11 am

      Hi Parasuraman S
      yes if they add the extra diode in the circuit the voltage is increasing
      and a voltage regulator is required and the pcb getting bigger and this need more space and more components the size of this pcb is only 22x15mm the smallest one that i have ever seen yes could be the economical reasons forced the manufacturer to make this lamp in this way.
      thanks for comment

  3. Gerald

    December 24, 2015 at 8:21 am

    Hi Beh,

    Well done, thanks for sharing. Like Albert this is the first time I see the inside of those LED lamps. I have a number of them installed at home since a couple of years ago and none has failed so far (touching wood). I have taken apart a large number of CFL that failed after a couple of months and all of them failed because of the electronic components, none of them failed because of the CFL itself. Your interesting article shows that the history repeats itself. New technologies but the same old mistakes; cheap and poor quality components. Well, this keeps us on the job 😉

    Cheers and Happy New Year to all the Electronic Repair members.

    • beh

      December 24, 2015 at 11:23 am

      Hi Gerald
      yes as you told the poor quality of electrolyte cap also could make this problem this cap is belong to a unknown manufacturer with name of XZ.
      actually these kind of productions are not belong to big manufacturer in china just small work shops are assembling these lamps but in a huge amounts and then instant export to thirsty world of consuming the electronics.
      GERALD happy new year and thanks for comment.....beh

  4. Justin

    December 24, 2015 at 2:14 pm

    Ooh! Very nice!

    • beh

      December 24, 2015 at 4:02 pm

      you are welcome

  5. Yogesh Panchal

    December 24, 2015 at 2:56 pm

    Beh, good job! thanks for sharing.

    • beh

      December 24, 2015 at 4:03 pm

      you are welcome Yogesh

  6. Robert Calk

    December 24, 2015 at 2:58 pm

    Thanks for the article, Beh. It's better to pay extra for quality devices when we can.

    • beh

      December 24, 2015 at 4:03 pm

      yes this is true and thanks

  7. Royce

    December 24, 2015 at 7:18 pm

    Yes a very good article, thank you for info.

  8. beh

    December 26, 2015 at 1:51 am

    ROYCE thanks for support

  9. Dennis,

    December 26, 2015 at 10:56 pm

    Beh, well presented. Thank you

    • beh

      January 4, 2016 at 12:57 pm

      you are welcome DENNIS

  10. reza

    December 30, 2015 at 1:03 pm

    Hi mr beh
    thank u for sharing this good article.

    • beh

      January 4, 2016 at 12:59 pm

      thank you MR REZA

  11. Humberto

    January 8, 2016 at 11:27 pm

    Hi beh, cheap devices China made cause a lot of troubles, they save electronis in the design.
    Thanks for the article, I had never seen one of these devices inside

  12. beh

    January 13, 2016 at 10:36 pm

    Hi Humberto
    yes these cheap device are every where and are very problematical .
    thanks for your comment and you are welcome


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