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Saving Computer SMPS – PART 5

By on May 20, 2023
atx power supply repair








Continuing my efforts to reuse as much Computer SMPS as possible, following two cases are being shared to promote service of such ATX Power Supplies. There is a general tendency to discard and buy a new one, indirectly adding up E-Waste. My intention is to arrest such throw-aways!


bad atx repairatx repair

Capacitors were found bulged and were removed.

I did a ring test and found it healthy:

ring tester check ok

On checking the caps, the values were way out:

testing capacitor

Replaced all the capacitors and retouched the board very well and cleaned it thoroughly using IPA. Then looked for any man made shorts, which are likely as we do the retouch fast without observing the tip of the iron touching adjacent points. There were two such cases, which I rectified. Then applied power with a load of 12V, 25W automobile bulb, along with the SMPS fan.

The ATX power supply checker showed healthy result. I allowed it to run for some time, before closing the cover and taking up the next. Incidentally, this again is a part of my free service to the hospital. I do not even collect the cost of spares!

fixing atx

  1. MERCURY KEZ-M200 :

repair atx power supply

I have worked on this SMPS long back. The tank capacitors were found burst. Fuse was blown. All rectifier diodes were short. Removed these and then did a ring test with a healthy result. Then replaced these defective components. The board was in good condition without a need for retouch.

All other electrolytic capacitors were found to be ok. ESR reading was also good! So, applied power like in case (1) above with a good result:

how to fix a bad atx power supply

Mission accomplished with double satisfaction getting added to the collection!


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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You may check on his previous article on Saving Computer SMPS – PART 4




  1. Anwar Yunas Shiekh

    May 20, 2023 at 6:50 am

    Keep 'em PARTS coming; power supply repairs are the best!

    • Parasuraman S

      May 20, 2023 at 3:42 pm

      Many thanks for your encouraging comments!

  2. Albert van Bemmelen

    May 20, 2023 at 2:36 pm

    I kept a lot of these boards from old no longer working power units for spare parts and threw away the large metal cases since they take up too much space. And on those boards I noticed that mostly all power transistors were still fine. Which points evidently to those bad e-caps like you many times explained. And coils and transformers probably hardly ever deteriorate.

    • Parasuraman S

      May 20, 2023 at 3:43 pm

      Your observations and comments are very accurate and apt! Many thanks!

  3. Yogesh Panchal

    May 20, 2023 at 2:49 pm

    Still we have jobs coming because of electrolytic capacitors.
    Good Fix! Sir.

    • Parasuraman S

      May 20, 2023 at 3:43 pm

      Many thanks, dear!

  4. Arunkant L Pandit

    May 21, 2023 at 2:43 pm

    Your free service and paying for components from your pocket is indeed a noble work of humanity.This is a good way to pay back to society. Nice job Sir.

    • Parasuraman S

      May 22, 2023 at 12:15 am

      Many thanks for your encouraging comments and support!

  5. M Yachad

    May 22, 2023 at 12:21 pm

    That is the FIRST time I have seen "Nichicon" capacitors burst like the Chinese junk. In 30+ years of this work, I have never seen any Panasonic or Nichicon capacitor burst. I find it very hard to accept that a genuine Nichicon will fail like that. Could these perhaps be counterfeit?

    • Parasuraman S

      May 23, 2023 at 10:44 am

      Let it be any brand, the quality of capacitor deteriorates over time and it burs on sudden overload. I have seen many Nichicon caps also like these. Many thanks for your input and comments!


    May 22, 2023 at 7:35 pm

    If you was close to me, I have a lot of working smps and some not working, you have got some, Sometimes the owner will just throw away a computer just because of a little fault and buy another one.

    • Parasuraman S

      May 23, 2023 at 10:46 am

      Yes, I have felt the need to be within the proximity of many of the experts here. But what to do, we all have our bread is fixed in one place and we need to be living there! Many thanks for your comments and encouragement!

  7. Bonkie

    May 22, 2023 at 10:42 pm

    good job sir
    i keep learning from you guys

    • Parasuraman S

      May 23, 2023 at 10:46 am

      Many thanks!

  8. Waleed Rishmawi

    May 23, 2023 at 1:30 pm

    computer power supply expert. keep up the good work and keep them up and running. have a blessed day

    • Parasuraman S

      May 24, 2023 at 8:39 am

      Many thanks for your supporting comments!

  9. Allen

    May 23, 2023 at 6:39 pm

    Thanks for the video.I have watched several of your videos and have enjoyed all of them. they are very informative.

    • Parasuraman S

      May 24, 2023 at 8:40 am

      Video? I have not posted any Video! Anyhow, many thanks for your comments!


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