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12V, 5A LED Driver SMPS Repaired

By on November 9, 2016










One of my friends had informed me a few months back that one side of the Serial LED lights do not light up. When I went there and saw, it was fixed on the roof. He had two sets fit on the roof, one on each side. So, I had told him to get an electrician to remove the driver unit and bring it to me. Since getting an electrician to get such work done is almost impossible here, one has to wait until a major work arises.

So, this got delayed and finally, the unit was delivered to me yesterday. I opened the unit and just look at what I found inside and what caused the breakdown, and damages on the PCB:



The strange coincidence is that only the other day, an article was published in this forum about lizard causing a similar damage!  As mentioned by me there, I had to once again witness the charred lizard and experience the nauseating rotten smell, though far less this time! Another coincidence is that the fuse had not only blown, but the glass cracked and shattered!  This could be caused by the fuse wire developing resistance over a period of time and burning like the filament of an incandescent lamp before finally blowing off, which broke the glass!

I disposed of the dead lizard, cleaned the PCB and the bottom plate using Spirit thoroughly. Cleaned my hands with Hand Wash to prevent any contamination.  On inspection of the PCB, I saw that positive rail was charred in one spot. Fuse was blown, as mentioned earlier and the Bridge Rectifier was dead short! The heat produced due to sudden rush of current, had created several dry solders in the primary section, and some of the soldered joints were like cast iron! Checked all the components in the primary, removing some of them like the Mosfet. Did not find anything wrong. Completed dry solder patch up. Connected a jumper in the positive rail and did a thorough cleaning of the PCB once again.


Connected a 60W bulb in place of the fuse and a mains cord, and tested the board. The bulb lit for a second and became dead, and the output was showing 12.11V, indicating that everything was well in the unit:


From the second photo at the beginning of this article, you will notice that the connections are dye stamped on the body; First two pins AC line in, third one Earth Pin, fourth and fifth are ground (-) and sixth and seventh are positive (+) for connecting the Serial LEDs. The power supply is rated for 12V, 5A.

So, connected 3.15A Fuse by soldering terminals at both ends. Rechecked the unit connecting a 12V 30W Automobile Bulb. It lit brightly:


Here is the unit fit along with the defective components:


Another ‘dirty’ job completed ‘neatly’!


This article was prepared for you by Parasuraman Subramanian from India. He is 66 years old and has more than 30 years’ experience in handling antiques equipment Valve Radio, Amps, Reel Tape Recorders and currently studying latest techs classes conduct by Kerala State Electronics Technicians’ Association. He was a BBA graduate, retired as MD of a USA company.

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You may check on his previous repair article below:




  1. Albert van Bemmelen

    November 9, 2016 at 2:40 pm

    Another dead Lizard caused a dead 12V 5A Led driver Board. I'm sure glad we do not have Lizards in my country. Thank you Parasuraman Subramanian for the article. We do have Stone-Martens who bite open Car Cables underneath the Motorhood. (But maybe you also have those in your country too?). Apparently because the Car Cables attracts them because of the fish smelling 'plastics'. We can buy spraycans with Anti-Marter-Spray to avoid these dangerous Cable 'attacks'. My friend's VW Passat had one of these visitors too and afterwards one of the Cables coming from the Engine Control Unit was eaten through. Sadly he was never able to figure out what its function was. Because the Cable disappears in one gigantic closed Motorblock. And removing or opening that is a very intensive and therefore costly operation. The 'eaten' Cable was not mentioned in the Car Manual either.

  2. Gerald

    November 9, 2016 at 6:23 pm

    Hi Parasuraman,

    Nice article, thanks for sharing. Wow, this lizard got really fried...
    When I was in Indonesia the electricity supply company decided to upgrade from 110V to 220V, almost overnight... The panic and problems it created is another story. Anyway during the first months of the 220V we had a number of shorts from behind the power outlets and light switches, all caused by fried lizards. Looks like that the lizard had learned to live and keep their distances with the 110V but didn't survive the upgrade to 220V! It made me sad.


  3. Bhupendra

    November 9, 2016 at 8:43 pm

    Hello Sir,
    I am interested your article 12v 5a power supply.If fuse is blown bridge diode and switching transistor /MOSFET also damage.Sir I am also repairing 12v 10a,20a & 30a CCTV camera power supply.

  4. Paris Azis

    November 10, 2016 at 1:35 am

    Hi Parasuraman

    Another one successful repair, saving this PSU from the dump. Good news for its owner,bad news for the lizard! The poor creature was found in the wrong place at the wrong time...A good lesson for anyone of us working with mains voltages...

    Best Regards

  5. Robert Calk

    November 10, 2016 at 2:14 am

    Poor lizard... Thanks, Parasuraman.

  6. Bulent NUR

    November 10, 2016 at 2:56 am

    Nice job, thanks for sharing!

  7. Cliff

    November 10, 2016 at 4:36 am

    Had the same problem in dish washer with garden slug control board burnt out
    beyond repair new board £130

  8. Mark

    November 10, 2016 at 5:58 am

    Hey Parasuraman,
    Seems to be a real problem with lizards!
    Our main problem in the automotive industry, particularly in the harsh conditions of Australia are rats that chew through the wiring. They can do some unbelievable damage. It creates all sorts of havoc and makes diagnosing a real pain!
    It was a lucky break to see all the components listed on the board. That certainly makes tracing circuits a lot easier.
    Well done on a successful repair!

  9. Muiddin

    November 10, 2016 at 10:40 pm

    Wow! I like the order by which the problem was solved.good job .thank you

  10. mahmoud_tajpour

    November 11, 2016 at 3:51 am

    Hi Parasuraman thanks for sharing because this is the best for me.

  11. Parasuraman S

    November 11, 2016 at 7:52 pm

    I thank each one of you for your encouraging comments.

  12. Tito Kanshulu

    November 12, 2016 at 10:46 pm

    Good work Sir. I do not know what these lizards want. I faced a similar situation with somebody's TV. About how the gecko got into the tv remains a mystery because the tv was tightly covered.

    • Parasuraman S

      November 14, 2016 at 2:42 pm

      From the eggs that get dropped inside. The eggos hatch because of the heat! But what surprises me always is how does it survive without food or water (?) for such a long time?

  13. Humberto

    November 16, 2016 at 12:31 am

    What a lizard! Good repair and photos and explanations too.

  14. Muthukumar

    November 16, 2016 at 10:02 am

    Hai sir I following in your article ,I learned in electronic step by step pls guide me sir,

    • Parasuraman S

      November 17, 2016 at 6:57 pm

      Very nice to hear that it has been useful to you. Many thanks!

  15. GMB

    November 29, 2016 at 6:48 am

    Can you fix the poor Lizard??! 😉

    • Parasuraman S

      January 14, 2017 at 2:25 pm

      Only the Creator can do it!


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