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What Do You Think About This Question?

By on April 3, 2012

Got an email from a member

“Jestine

I want your opinion on this. I talked to an electrical technician over the weekend. He told me repairing SMPS is not worth it. His experience is that when a SMPS goes bad it weakens other parts and the chance of fire is to great. Replacing the SMPS is best. What do you think on this?
Thank You”

So what is your opinion on this question?

 

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20 Comments

  1. Galib

    April 4, 2012 at 8:03 am

    I am little bit agree with that but not all the time . In my experience - sometimes I found that SMPS is not starting-up, even all parts are OK in SMPS section ! I have searched over internet - they all highlights at capacitors in those problems . But I have little bit different opinion in that condition . I highlight on Resistor - specially Biasing and Feedback Resistor . Those Resistor Values are absolutely OK but surprisingly SMPS does not start !!! If I Replace those Resistor with new same value or increase value or decrease value, then SMPS turns back it's life again !! I don't know why it happens !!! It is totally unknown to me !! can you suggest me - why this kind of problem rises .

    Thanks

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    • Jestine Yong

      April 4, 2012 at 10:47 am

      HI Galib,

      It could be the resistor breakdown when under load. I personally have seen it one or two only but one of my repair friends told me he had experienced a start up resistor 220k tested good with digital multimeter but fail when under load.

      Jestine

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  2. siebo

    April 4, 2012 at 11:37 am

    i disagree. i repaired many power supplies and they're still working fine. If it takes to much time to repair then replacing is cheaper in some cases

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    • Jestine Yong

      April 5, 2012 at 1:33 am

      HI Siebo,

      In fact I also disagree because I have repaired lots of power supplies in my entire career. After repaired we let it run in a burn in test and if there is any weaken components it will surely surface. Even if the problem did not come out during the burn in test at least those weaken components are original components. Unless if you use substitution parts and replace a higher than normal fuse ampere.

      Jestine

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  3. beh

    April 4, 2012 at 7:38 pm

    HI JESTINE

    please tell me what do you mean other parts are getting weak. which parts are getting weak ? the parts in main board ?...and/or?
    beh

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    • Jestine Yong

      April 5, 2012 at 1:29 am

      Hi beh,

      He is referring to the power supply board. The parts are getting weak could mean those corresponding components that could be not in good condition. For example the resistor and cap value are slightly up and etc.

      Jestine

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  4. beh

    April 5, 2012 at 5:51 am

    HI JESTINE
    i agree with you if we change culprit parts in smps the board will work to a indefinte period and dose not weaken any things else those parts that thier life span is finnished
    thanks
    beh

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  5. THULANI

    April 5, 2012 at 8:04 am

    Jestine i think the most problem in power supply there caps they dry up esr

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  6. wael

    April 5, 2012 at 6:57 pm

    15 years of smps repair and have never seen resistor that fail under load

    resistors when they fail they increase in value(markedly)

    or open circuit

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    • Jestine Yong

      April 6, 2012 at 12:23 am

      Hi Wael,

      Good question-it can be increase in value or open circuit.

      Jestine

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  7. bob lou

    April 9, 2012 at 11:06 am

    I used to work in a electronic repair shop...we fixed dozens of vcr's and tv's with switch mode power supplies. The secret to repairing these units is to use the correct parts. And sometimes only an orginal part will work...

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    • Jestine Yong

      April 9, 2012 at 9:07 pm

      Hi Bob,

      You are right. Using original part replacement will get your equipment to work without worrying anything.

      Jestine

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  8. Arnel

    April 9, 2012 at 3:59 pm

    I have also experience of the different smps of personal computer P.S.U.I just always encounter a a bad resistor and a power transistor in primary part of the circuit.I just collect a transistor or resistor in other P.S.U that could not be use.But It will works but supposedly it will not work longer.It will breakdown or else it will burnt the other part.
    I encounter also replaced the powerboard of the Dell LCD with the same output of the dell powerboard.It will works but In a month of use the powerboard was also burned.

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    • Jestine Yong

      April 11, 2012 at 12:28 am

      HI Arnel,

      The power board burnt or the components burnt?

      jestine

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  9. Jackson Lui

    April 10, 2012 at 6:07 am

    Hi Jestine,
    I can see that a failure of one part could well overstress the other parts. But I could play safe and just replace the unit. (Depends on what kind of service equipment. If the service contract have plnalty. Eg. Banking equipments. Keep the down-time between failure must be less.).  No choice to replace the new parts.
    With Best Regards
    Jackson Lui -Hong Kong.

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    • Jestine Yong

      April 10, 2012 at 9:17 am

      HI Jackson,

      Thanks for the suggestion.

      Jestine

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  10. Damdin

    April 10, 2012 at 8:59 pm

    I do not agree with this. I repaired so many PC PSUs, notebook adaptors since 2008, until now I didn't heard that they failed. There were even hard to repair cases with too many burnt components, but after replacing them, even hand wound chokes they're still working fine.

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    • Jestine Yong

      April 10, 2012 at 9:34 pm

      Hi Damdin,

      Nice to see you again and thanks for the good comment!

      Jestine

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  11. Malcolm Telford

    April 11, 2012 at 11:02 pm

    It's interesting, but the problem with the argument is that if you did not repair smps then you'd end up never repairing anything. Other circuits will have weakend components as well. Afterall SMPS is just another electronic circuit. Sure, it works hard but so do many other electronic circuits like vertical oscillators, and horizontal drivers. I think economics should be the dictator as to whether you will repair and replace. Easy and cheap enough to replace standared PC power supply. Other SMPS maybe unique, expensive or irreplaceable.

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    • Jestine Yong

      April 12, 2012 at 8:45 am

      HI Malcolm,

      You got a point. May be that guy was referring only to power supply and not other type of circuit. Even if he only refers to power supply but it still be repairable unless if we can't find the components or the whole power supply burnt beyond recognition.

      Jestine

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