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Thread: Interesting comment about SMPS component life

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    Default Interesting comment about SMPS component life

    http://www.repairfaq.org/sam/smpsfaq.htm#smpsror

    "Nothing really degrades in a switchmode power supply except possibly the electrolytic capacitors..."

    I would add fan to this comment, but I suspect that even then some people here would not agree.
    Last edited by Jon Gerow; 07-07-2018 at 02:31 PM.

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    Short term, I would agree with electrolytic capacitors and fans.

    Long term, I would think those interference caps (X2 capacitors) could be damaged and potentially fail, if load varies a lot then maybe heat cold cycles could cause solder joints to fail (cold joints etc) ... then humidity could be sucked into the circuit board (they make motherboards for some countries with different weaving for more resistance to humidity these days) and I suppose humidity could be absorbed in diode or mosfet packages or those standby DIP chip with integrated high voltage mosfet making them blow out (if some over voltage on the mains won't kill them first)

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    Quote Originally Posted by mariush View Post
    ... then humidity could be sucked into the circuit board (they make motherboards for some countries with different weaving for more resistance to humidity these days) ...
    I never understood that, the gaps are filled by epoxy resin; I often wash boards, dry them off and put them straight into service.

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    Quote Originally Posted by ashiekh View Post
    http://www.repairfaq.org/sam/smpsfaq.htm#smpsror

    "Nothing really degrades in a switchmode power supply except possibly the electrolytic capacitors..."

    I would add fan to this comment, but I suspect that even then some people here would not agree.
    I'm one of them. I disagree.

    I mean.. for fucks sake, every component within the PSU has a life expectancy calculation formula with derating curve.

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    Quote Originally Posted by jonnyGURU View Post
    ...for fucks sake...

    If I used that kind of language, you would probably kick me out

    Anyhow, what wears out in a transformer, diode, transistor? Take for example a server CPU, almost 1 billion transistors running hot 24/7 for years and hardly any fail.

    Can you point me to "life expectancy calculation formula"; derating curves are something different.
    Last edited by ashiekh; 07-07-2018 at 04:12 PM.

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    Quote Originally Posted by ashiekh View Post
    If I used that kind of language, you would probably kick me out
    Not at all. Not sure why you think that.

    Quote Originally Posted by ashiekh View Post
    Anyhow, what wears out in a transformer, diode, transistor? Take for example a server CPU, almost 1 billion transistors running hot 24/7 for years and hardly any fail.
    Heat and heat cycles are what cause them to degrade and die. They don't die "by design", but to assume that FETs, diodes, etc. in an SMPS are "just as good as day one" is naive.

    Keep in mind that one of my first jobs in this industry was in the RMA department of a big wholesaler. I've seen 2" tall blue and white flames shoot out of CPUs, GPUs, RAM, chipsets, etc. for inexplicable reasons.

    And now that I'm at Corsair, I can say I still see that trend. Based on some of what's in that article, and your own input about fans, that every failed PSU that comes back to Corsair under warranty failed because of failed caps or fans.. That's farthest from the truth.

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    Quote Originally Posted by jonnyGURU View Post
    Not at all. Not sure why you think that.

    Good to know; I'll save that for when I am angry.

    Now it is true that at very high temperatures there is diffusion aging in semi-conductors.

    Design plays a big role; if there is a surge the diode cannot withstand then there will be failure, but that is not from wearing out.

    I didn't say they don't fail; I said they don't often wear out.
    Last edited by ashiekh; 07-07-2018 at 04:43 PM.

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    Quote Originally Posted by ashiekh View Post
    Design plays a big role; if there is a surge the diode cannot withstand then there will be failure, but that is not from wearing out.
    Absolutely. And I've seen some bad designs that cause infant mortality.

    Unfortunately, most reviews don't catch these design flaws. As long as the PSU performs as expected when reviewed, most users would never know.

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    We are in agreement?

    Hell just froze over....
    Last edited by ashiekh; 07-08-2018 at 12:21 AM.

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    My China 12V 10A power brick died not because of fan or capacitor but one of the secondary side diodes failed shorted. My computer draws max 50W from the wall at full load.

    A PSU that uses fans and capacitors as a timebomb is shoddy design - the rest of the product is overspecced. All of them should be part of the timebomb.

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