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Thread: Funny smell from PSU

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    Default Funny smell from PSU

    Hi,
    I have just inherited a 10 year old IT gear, with 10 years worth of dust.
    So I strip it apart as much as possible, and went crazy with a air duster can.
    After putting it back together and power on, then i notice a funny smell. The best way to describe the smell is something in between new electronics smell and burnt electronic smell.

    It definitely originate from these 2 parts in the PSU.


    As you can see in the picture, there's still some dust that the air duster can't remove. But i'll be reluctant to strip it apart any further.
    Other than the smell, still works fine. I have it powered on for a few hours already.
    I thought if something is going burnt it will be dead by now ? I'm confused if this is going to die or not ?

    Regards.



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    I think those pink pads are thermal compound to transfer heat to the cover. Those are probably transformers that are running hot and dissipating odor. You might want to put some conductive grease, the white stuff, on those where they meet the cover.

    I had an IBM PS2 computer that had a failing power supply. It made an awful fishy smell that was either a transformer or capacitor heating up. I kept blaming some other more expensive HP equipment next to it because both were usually switched on.

    The part values change with age and the switcher starts to run at a frequency or PWM that is outside the operating limits. Then stuff heats up and fails.

    Sent from my SM-T350 using Tapatalk
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    I think the pad in the center is actually on a heatsink carrying the SMPS transformer switchers ...lots of dirt&dust around, I see a few spots I can plant petunias or spuds =)

    Also. all the thermal transfer compound between every semiconductor and heatsink will be dried out and not doing anything (except make things run hot), ergo all semiconductors should be unbolted from their heatsinks, and the transfer compound replaced.

    Then like RFI-EMI-GUY says, if any of the components have wandered out of spec (particularly capacitors), they'd need be replaced as well or the SMPS will be running hot -- this happens with the ESR of the caps increases over age

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    Quote Originally Posted by RFI-EMI-GUY View Post
    I think those pink pads are thermal compound to transfer heat to the cover. Those are probably transformers that are running hot and dissipating odor. You might want to put some conductive grease, the white stuff, on those where they meet the cover.
    Good solution. I used some leftover CPU thermal grease on those pink pads, ran it for an hour, and hardly any smell anymore. Thanks.

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    A lot of older computers need this type of care.

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