PSU transformmer melted

Discussion in 'General Electronics Chat' started by Potato, Sep 10, 2014.

  1. Potato

    Thread Starter New Member

    Sep 10, 2014
    Newbie here, this is my very first post

    First of all I am not familiar with electronics, that is why I am here seeking help

    Yesterday my desktop computer stopped working. I unplugged everything to check, and found that the PSU (Power Supply Unit) has fried

    I did a visual check on the motherboard and could find no sign of short circuit or whatnots, and the "smell test" also turned up no "burnt smell"

    I opened up that fried PSU and found that the plastic insulation over the transformer has "melted", actually not "melt" per se, it's that it has "dark brown lines" on that yellow plastic shrink wrap

    Back to the desktop. I could easily change the PSU and power up the machine, but before I do that, I need to make sure nothing else is wrong, that is why I am here

    Can anyone tell me what makes the PSU transformer melted ?

    Sorry, for some background. My PSU is a 550 watt brand name PSU, and my desktop is a simple 4 core intel chip (non-turbo, non-overclock) setup, with one HD and one DVD drive. I do not use any GPU card, relying on the on-board GPU processing

    I use the desktop for normal spreadsheet / word processing and do not watch movies nor do any fancy things on the machine

    Back to the main concern --- What is/are the possible causes that can melt my 550-watt brand-name PSU's transformer?

    If I put in a new PSU would it be safe? Or would the same thing happen?

    I thank you in advance for any suggestion / idea that you can share

    Thanks again !
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    So the yellow shrink wrap band is much less of an issue than the "Transformer melting". The amount of anti-oxide in the plastic film is the question here. Plastics will turn yellow/tan in any warm area. New power supplies have components that will see 85+ degrees. Many films will yellow at those temps over time.

    Send a photo.

    Power supplies die all the time. It probably has nothing to do with the yellowing transformer wrap.
  3. tom_s


    Jun 27, 2014
    try the new power supply, if you haven't done it before, make a note of where the sockets go, there are 2 that plug into the motherboard, main power and cpu power. just put those 2 in and you should have a standby led on the motherboard that will light up, don't worry if there isn't one. press the power on button, if it starts up your good to go. power off and replace the rest of the connectors.

    long startup process cut short (not feeling too pedantic, its bedtime) power sent to motherboard, motherboard checks voltages, pull power good pin to 0v, power supply turns fully on.

    and regarding the old supply, most of the time i find them with caps that go dry or diodes open/short circuit. your name brand one means nothing, i change those as well though admittedly not so often.
  4. wayneh


    Sep 9, 2010
    Is that the only evidence you have that the PSU has "fried"? You may be chasing the wrong problem. If it's easy to swap out for another PSU, that's certainly a worthwhile experiment. But stay aware that there could be other problems.
  5. Potato

    Thread Starter New Member

    Sep 10, 2014
    Thanks for the replies

    I only want to make sure that plugging in a new PSU is safe.

    The only thing that has fried is the transformer - I have pried open the PSU's transformer and yes, that thing melted and whatever "paste" or whatnots has liquefied and turned into oily/greasy smudges

    That is why I posted my message because I need to be awared of what else that could fry that PSU transformer --- as the PSU's output (at 550 watt) is much higher than the CPU ever could use (not more than 300 watt, even at peak), and if something can fry that transformer I am weary of perhaps something else (maybe wiring, maybe wall socket, maybe whatever that I might have overlooked) that could strike again, even with me putting in a new PSU

    Thanks again for your suggestion - and if you have any other idea to share, please do
  6. Lestraveled

    Well-Known Member

    May 19, 2014
    Losing a power supply is very common. Go ahead and replace it.