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Floodlight Power Adapter Problem Repaired

By on July 26, 2013

Last May I posted about repairing LED Floodlight. You can check the link again below:

Today posting is about repairing the LED Floodlight power adapter. Few days ago my friend sent to me another batch of LED Floodlight. This batch had the power adapter outside and it was quite easy to remove from the unit.



The complaint was no power and the first thing I checked was the main fuse and it was open circuit. The power board does not have any burn mark or bulge electrolytic capacitors. As usual, once the main fuse open we have to check on the bridge rectifier.


If you are a newbie I suggest that you check the 4 bridge diodes (1N4007) off board. Since I’m used to check bridge diodes on board, I found two diodes shorted. I don’t just stop at this point, I carried on my inspection to check on power transformer with Blue Ring Tester and found the primary winding to be good. The secondary diode also was tested good.

I concluded that at that very moment only the diodes and the fuse were at fault. Usually when I found one or two bridge diodes shorted I would replace the four of them. If not I’m sure later on (perhaps in few months’ time) the other two bride diodes may give way too.


After replacement of the diodes I connected a 100 Watt bulb across the fuse solder points. I then used my faithful Greenlee Digital Multimeter and set to Volt range and placed the probes on the output terminal. When the power was applied, the bulb did not even light up at all (this indicates there was no short circuit) and I could see the voltage result from my multimeter.

With this test, now I can remove the bulb and put in the main fuse without worrying that the power section or the semiconductors would blow again. From the photo you could see the output voltage measured 26.39 volt and the LED Floodlight happily lighted.

output voltage


Just in case if the bulb is extremely bright and would not go dim then I have no choice other than to direct replace the power IC and retest.


After done this repair work I began to check on another similar power adapter and found that there was only a shorted secondary diode. The part number was SR5150 rated at 5 ampere 150 volt as seen from the photo below.

schottky diode


Conclusion- This is a small power adapter thus it is not tough to repair it. Just follow some simple troubleshooting procedure and I believe you can have the same success like me. If you want to be good in power supply repair you can check out my best seller power supply repair ebook HERE.







Jestine Yong

Please give a support by clicking  on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments. By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.



  1. shihab kably

    July 26, 2013 at 6:58 pm

    thank you for sharing this experience

  2. Sanan

    July 26, 2013 at 8:25 pm

    Hi Jestine,

    Could you please give a clear explanation to the connection of 100 Watt bulb across the fuse solder points. What is the purpose of that and what does it indicate? Simply put, what is the process going on when we do connect a light bulb across the fuse solder points. I need a simple explanation to that. Thank you in advance for the time you take to reply to my message.

    • Mike

      July 27, 2013 at 4:38 am

      If there is a short the light bulb will light up. This method is used to save fuses...

      • Jestine Yong

        July 27, 2013 at 9:27 am

        HI Mike,

        You are right and also to save the components you have just replaced.


  3. peter djuh

    July 27, 2013 at 3:56 am

    thanks alot Mr Yong, GOD will continue blessing for these your wonderful articles

    • Jestine Yong

      July 27, 2013 at 9:27 am

      Hi Peter,

      You are welcome.


  4. Waleed Rishmawi

    July 27, 2013 at 5:07 pm

    thanks for sharing the article with us. your experience is appreciated by me and a lot of tech. around the world. God bless you

    • Jestine Yong

      July 28, 2013 at 2:37 pm

      Thanks Waleed.


  5. Hla Htay oo

    July 27, 2013 at 6:27 pm

    Dear Mr. Yong,

    I am Mechanical Engineer but very obsess in electronic repairing like this kind of SMPS and related things. I started receiving your SMPS repair articles from my G-mail couple days ago and indeed very useful for me to learn and go for practicle. Thanks a lot Mr. Yong...

    • Jestine Yong

      July 28, 2013 at 2:38 pm

      HI Hla,

      You are welcome.


  6. sodjah

    July 29, 2013 at 7:25 pm


  7. Mark Tembo

    July 30, 2013 at 8:13 pm

    Thanks a lot! Nice artical

  8. mathias

    August 1, 2013 at 6:39 pm

    Hello Mr Jestine Y. thaks for all Ur articles.I have problems with laptop power adapters they return power to the source. as in the case of using a generator pls I need Ur help. thanks. email

    • Jestine Yong

      August 3, 2013 at 5:38 pm

      HI Mathias,

      Sorry I don't get your meaning. Does the adapter have output voltage? What have you checked in the adapter?


  9. ben

    August 6, 2013 at 5:31 pm

    Hi Yong
    thanx with the postings Great work,sorry, better late then never,for my commet.

  10. Henry

    August 8, 2013 at 10:32 am

    Hi Justine,
    Another nice article. Thank you.
    Looking at the picture I can not find the 2 Amp fuse.
    Could you please point out to its location on the board?

    • Jestine Yong

      August 8, 2013 at 11:49 pm

      Hi Henry,

      The location is on the right side of the power supply board. Since I have removed the fuse you will not be able to see the fuse location. For your information the main fuse is usually located at the ac supply input.


  11. Ner

    August 13, 2013 at 9:34 am

    Very good tips on repairing. Thanks for sharing


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