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Crude Drawing To Find Out Burnt Components Part Number

By on May 25, 2018
electronics drawing for repair power supply












This Brite Lite Adapter belongs to one of my friends, who brought it to me knowing my craze to restore any electronic gadget, irrespective of its cost. The complaint was ‘dead’!

power adapter repair

Opening is possible by just peeling away the silver sticker at the bottom, and removing one holding screw.

how to repair power adapter

On visual inspection, found that one transistor had burst, and on further cold tests, a few other components were too found defective. One 2N3904 was burst, another MJE13003 short, opto-coupler short, Diode short, 2 SMD resistors open, green capacitor burnt, and another changed value.  All these were in the primary. On the secondary, one diode was short! So, this was a massive heart attack!

Whenever we see such mass failure, we have to check whether the SMPS Transformer is ok. I checked it with Ring Tester and found it to be ok. But in order to make sure, I removed the MJE13003 and connected a Universal Module, after replacing the diode in the secondary side. The LED lit indicating that all was well in the secondary side.

universal power module

Removed them one by one, noting down the reference number from the PCB and the corresponding component.

bad components in power supply

While replacing the 13003 transistors, we need to be careful, as the order of pins might not be same, as you can see from the below pictures:

electronics drawing for repair

I also drew one circuit diagram, which could help me in future (crude drawing!), from another working adapter that I use with my torch.

The circuits were identical. That is how I knew that the burnt transistor was 2N3904 and the value of burnt SMD resistor!

power supply hand drawn schematic

Then I drilled holes (using a special hand-drill) in order to replace the resistors, as the SMD was not available. I had to use three resistors in series to arrive at the value of 360 Ohms!

screw driver for opening power supply

fix power adapter

power adaptor fix

After rechecking that everything was ok, I powered it through the Serial Bulb.

how to fix and repair power adaptor

Assembled it back and left it on connecting the load and found it to be working fine.

how to repair a dead power adapter

Finally, the Adapter was saved from dump, though this might have made a hump on my back!


This article was prepared for you by Parasuraman Subramanian from India. He is 69 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.

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You may check on his previous repair article below:




  1. Anwar Shiekh

    May 25, 2018 at 10:50 pm

    Your stubbornness is something to admire

    • Robert Calk Jr.

      May 27, 2018 at 5:35 am

      Yes, Parasuraman has the tenacity of a tiger!

  2. Mihai

    May 26, 2018 at 12:46 am

    Good job Mr. Parasuraman,thanks for sharing your experience!

  3. Suranga Electronics

    May 26, 2018 at 12:58 am

    Good Repair job, Mr.Parasuraman.

  4. Paul

    May 26, 2018 at 1:11 am

    Thank you Mr Parasuraman Subramanian for work and best professional skills

  5. Graeme

    May 26, 2018 at 1:56 am

    Could you please expand on the "Universal Module" i am not familiar with this device.

    • Parasuraman

      May 27, 2018 at 12:40 pm

      I have discussed in detail with diagrams on Universal SMPS module in my previous articles, which is also covered by Justine Yong in his book. Hence did not want to repeat it.

  6. Albert

    May 26, 2018 at 10:59 am

    Another impressive job counting all the destroyed components in this power circuit. I do hope that "the Hump on your back" thing you mentioned was of no real significance after finishing this repair succesfully in the end!
    I still wonder though what you meant with: "you removed the MJE13003 and connected a Universal Module"? What universal module exactly were you talking about since you left out any info or schematic on this part?

    • Parasuraman

      May 27, 2018 at 12:41 pm

      Please my response above.

  7. James

    May 26, 2018 at 3:04 pm

    More wisdom for us to take in, thanks.

  8. Christian Adzic

    May 27, 2018 at 3:04 am

    Clear explained repairing with schematic.
    Good job and well done.

    I have a question:
    You wrote you connected a Universal Module to the transformer, If I understand it right.
    What kind of universal module is that?

    My best regards.

    • Parasuraman

      May 28, 2018 at 9:03 am

      Kindly see my replies above.

  9. Robert Calk Jr.

    May 27, 2018 at 5:34 am

    Good job, Parasuraman. Plus you got an article from the repair. Sounds like something I would do...

  10. Parasuraman

    May 28, 2018 at 9:09 am

    To all those who asked about universal module : Please read my earlier article:

  11. Justice

    May 30, 2018 at 7:03 pm

    Good work Parasuraman thank you.

  12. Yogesh Panchal

    June 12, 2018 at 1:07 am

    Excellent! sir,


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