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350 Watts ATX ALLIED SMPS Repaired

By on December 8, 2015
atx power supply repair











This Switch Mode Power Supply (SMPS) was brought to me and the complaint was it had a malfunction due to the PC was restarting continuously once and again.


The brand name was ALLIED model AL-C350ATX with the following features:

  • Voltage: 115/230 V ~
  • Current: 8A/4A
  • Frequency: 50/60 Hz
  • 350W max.

atx power supply repair

First step was to take out the upper cover, only four screws.

atx repairing

At simple sight there were some perceptible bulged e-caps in the secondary side of the circuit, let´s see some photos.

power supply atx repair

Note: Some of the capacitors were spilling out the electrolyte. There were in total 9 defective e-caps.

bad e-caps

All of them were substituted for similar ones, let’s see some photos.

repairing power supply

The critical components (switching transistors, Rectifier Bridge, big filter capacitors of the primary side, etc.) were checked on with the Digital Multimeter, and all of them were ok.

The SMPS was then put into functioning and see in the photos below the result.

repairing power supply atx

All the output voltages were ok this time, and when the owner of the PC connected the SMPS it worked perfectly fine (no more restarting). One week later I saw him and asked about his PC, and he told me it was working fine.

Mission accomplished.












This article was prepared for you by Humberto Rodriguez, one of our ‘Master Authors’ from Cuba.

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Note: You may check his previous repair article in the below link:



  1. gabriel

    December 8, 2015 at 11:01 am

    Thanks for that tip Humberto

  2. Merlin Marquardt

    December 8, 2015 at 11:26 am

    Bad caps. Good repair.

  3. Yogesh Panchal

    December 8, 2015 at 3:14 pm

    Good Job! Humberto.

  4. Albert van Bemmelen

    December 8, 2015 at 3:57 pm

    Good job Humberto. I noticed that you prefered showing the Voltages on a Analog Meter. Are you saving on the 9 Volt batteries? (LOL).

  5. Parasuraman S

    December 8, 2015 at 4:54 pm

    Good Job! These electrolytic capacitors seem to be top in the list of components that fail in any electronic device! Thanks for sharing!

  6. Allan

    December 9, 2015 at 2:04 am

    Hi Humberto, great diagnosis and thanks for sharing. I like this so much.

  7. Robert Calk

    December 9, 2015 at 2:06 am

    Good job, Humberto. That's a nice looking analog VOM you have. Maybe in your next article you can show us a good photo of the PCB?

  8. Ulises Aguilar Pazzani

    December 9, 2015 at 10:09 am

    Mr Rodriguez . Your are a great tech .like readding Your articles

  9. reza

    December 13, 2015 at 10:12 pm

    Hi Dear Humberto Rodriguez
    very good.

  10. Abdul Haleem

    December 14, 2015 at 11:26 pm

    Thanks Humberto Rodriguez. In my experience e caps in ATX PS fail due to heat or insufficient cooling inside the ATX housing. What I normally do is check for speed of the cooling fan, dismantle the fan and lubricate its bearing or replace the fan if necessary. I also advice customers to periodically put one of their hands behind PS and feel if there is enough air flow to confirm the fan is running.

    • mahienn

      February 11, 2016 at 6:41 am

      thank u sir
      abdul haleem

  11. Gurpreet Singh

    December 15, 2015 at 6:50 pm

    So many faulty capacitors. Good job. Thanks for sharing this article.

  12. raul salazar

    December 24, 2015 at 1:44 pm

    thank you so much for ur articles

  13. mahienn

    February 11, 2016 at 6:42 am

    good job sir
    Humberto Rodriguez


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