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Two Adapters Survived Sudden Voltage Surge

By on September 16, 2023
power adapter repair








These two adaptors survived the onslaught by sudden spikes; rather the electrolytic capacitors took the beating and saved the other costly components. Both of these ACAs belong to the hospital where I work and were brought to me in dead condition.

Case 1:

power adapter repair

As you could perhaps make out, all the caps in the output were bulgy. Same was the case with the tank capacitor too. I saw rust in the mounting screws of the diode in the secondary and the Mosfet in the primary.

As the ACA passed the preliminary ring test, I replaced all the electrolytic caps in the ACA and did a neat retouch of soldering spots. Then cleaned the board thoroughly using IPA. The board looked healthy after that.

fixing power adaptor

When I applied power through a Series bulb, the LED in the output lit up and on measurement on a load of 25W/12V bulb, it was a steady 12V. This indicated that the work was successful and the ACA was back to give its second round of service. The entire operation took only around half an hour or less.

how to fix a power adapter

Case 2:

Repair power adapter

Apart from bulged capacitors, there were corrosion all around. It had affected the TL431, Opto Coupler and the mounting screws as well. But all these disappeared neatly when I cleaned the board with CPC 2-26 followed by IPA spray. Replaced all the electrolytic caps, after checking SMPS transformer with Ring Tester.

Looked for any defective components both in the primary and secondary. Retouched the board with fresh solder and once again cleaned the board using brush and IPA. The board looked healthy after this work. I applied power through a Series Bulb and saw the LED lit up. Gave a load of 25W/12V lamp and checked the output in a multimeter with a positive result.

repairing power adapter surged

This entire work also took only less than half an hour, may be because of practice and knowing what to do step by step.

how to fix a broken power adapter

Perhaps you would notice from the label above that the Adaptor was bought on 18th January, 2012 and it is now revived for serving another length of time. What a saving at a negligible cost!

Missions accomplished successfully and double satisfaction got gathered to its collection without fail!

Note: My intention of sharing these works here is to drive home the fact that discarding these defective devices and going for a replacement is not a good proposal. We should save as much as possible and continue it as long as possible.


This article was prepared for you by Parasuraman Subramanian from India. He is 72 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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  1. Albert van Bemmelen

    September 16, 2023 at 5:26 pm

    Luckily you always have enough spare e-caps stocked for servicing! And again very nicely done SMPS repairs resulting in another good article!

    • Parasuraman S

      September 16, 2023 at 11:01 pm

      Many thanks for your comments and encouragement!

  2. Waleed Rishmawi

    September 16, 2023 at 5:27 pm

    Good job on the repair and thanks for sharing. Have a blessed day

    • Parasuraman S

      September 16, 2023 at 11:01 pm

      Many thanks, dear friend!

  3. Yogesh Panchal

    September 16, 2023 at 5:44 pm

    Good Fix!Sir

    • Parasuraman S

      September 16, 2023 at 11:01 pm

      Many thanks!


    September 16, 2023 at 8:08 pm

    Dear Sri Parasuraman
    Thanks for sharing two articles one on LED Bulb service and another one for
    Adapters. Enjoyed the repairing techniques you have adopted.
    With respects

    • Parasuraman S

      September 16, 2023 at 11:02 pm

      Many thanks, dear Natarajan!

  5. Anwar Yunas Shiekh

    September 16, 2023 at 10:36 pm

    When I replace a collection of capacitors I keep the good ones so I can later make a fast repair while I wait for new ones to come in.

    • Parasuraman S

      September 17, 2023 at 8:06 am

      Using a used capacitor is not advisable, however good it might be on test. It can fail on load. Many thanks for your comments!

  6. Imoudu.O

    September 17, 2023 at 2:51 am

    Good,fast fix.No method of testing secondary side of smps transformer yet I suppose!!

    • Parasuraman S

      September 17, 2023 at 8:08 am

      When testing the primary with Ring Tester, if there are any shorts in the secondary, it won't light up. So, to a certain extent, that check is enough! Many thanks for your comments!

  7. ivan rivera

    September 17, 2023 at 10:44 am

    Un gran saludo a todos
    Segun mi creencia el abultamiento de los condensadores electrolíticos se debería al tiempo de uso ,la temperatura, producto de los pequeños espacios sin enfriamiento y fundamentalmente a la mala calidad de los dieléctricos y a la perdida de tamaño a traves del tiempo Saco esa conclusion al comparar estas fuentes de poder con las antiguas japonesas Sony Panasonics JVC Que al sufrir
    transientes solo afectaban varistores y fusibles ,quedando el resto intacto Bueno creo que pase por alto que ahora estas fuentes funcionan a mayor velocidad de conmutación y las corrientes de fuga en los diodos que preceden a los condensadores electrolíticos, les provocan un aumento de su temperatura de trabajo
    A big greeting to all
    According to my belief, the bulging of the electrolytic capacitors would be due to the time of use, the temperature, a product of the small spaces without cooling and fundamentally to the poor quality of the dielectrics and the loss of size over time. I draw that conclusion when comparing these. power supplies with the old Japanese Sony Panasonics JVC That when suffering
    Transients only affected varistors and fuses, leaving the rest intact. Well, I think I overlooked that now these sources work at a higher switching speed and the leakage currents in the diodes that precede the electrolytic capacitors cause an increase in their temperature. job

    • Parasuraman S

      September 17, 2023 at 6:36 pm

      Good observation and expertise! Many thanks for your comments and valuable inputs!


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