Odd residue in PSU

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xpd

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#319518 2-May-2025 12:32

Had a PC returned as it wasnt working - they at least removed the dead rat from it first (honest). But upon inspection, someone has taken the PSU apart.

We cant figure out why...... and what is this mark on the inside of the casing ? Im starting to think someone has done a PSU swap on us.....

No smell of anything burnt, and no obvious blown caps etc.

XPD / Gavin

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tweake

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#3369900 2-May-2025 12:50

my first suspect would be the caps under the incoming mains next to the coil.

the other thing is if someone has spilt something.

xpd

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#3369903 2-May-2025 13:02

All the caps look fine. Spilling something there would be damn impressive considering nothing else is covered, and it was a sealed unit.

XPD / Gavin

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askelon

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#3369905 2-May-2025 13:03

Any sort of smell around it at all?

Rickles

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#3369906 2-May-2025 13:05

Cat jumped up on desk and sprayed in through the fan vent?

Rickles

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#3369908 2-May-2025 13:09

PS >my first suspect would be the caps under the incoming mains next to the coil.<

Don't some capacitors have a cooling oil sealed inside them?

tweake

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#3369912 2-May-2025 13:26

Rickles:

PS >my first suspect would be the caps under the incoming mains next to the coil.<

Don't some capacitors have a cooling oil sealed inside them?

not cooling oil. electrolytic have electrolyte in them, but others can have sticky goo in them to seal them.

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tweake

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#3369913 2-May-2025 13:32

given the bit of mouse crap in the pic, i wonder if a mouse crawled in and shorted on the mains and its remains have been removed.

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#3369915 2-May-2025 13:40

Is it actually residue, or moist dust causing corrosion in an area that potentially becomes somewhat an electro magnet spot with the coils close.

Have seen steel cases and components do this sort of thing when close to salt conditions. Purely because of the moisture content in the air and how it manages to find spots of calm airflow. But normally wouldn't extend along the bottom lip. Unless the bliter has been in there a while and peed on the side of it and it's surface tension has moved it along

xpd

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#3370016 2-May-2025 15:35

tweake:

given the bit of mouse crap in the pic, i wonder if a mouse crawled in and shorted on the mains and its remains have been removed.

Err... where ? Theres no droppings in that pic at all (apart from all the crap on the table in the background)

Theres no way a mouse would get in it when sealed anyway.

The rat was found on the mainboard (because someone had removed the PC case). I highly doubt the rat undid the PSU screws, took off the casing, took a piss, and then put the case back on. :)

I'd almost say it was a cap exploding, but everything is there in one piece and looks fine, and no smell.

XPD / Gavin

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tweake

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#3370022 2-May-2025 15:45

xpd:

tweake:

given the bit of mouse crap in the pic, i wonder if a mouse crawled in and shorted on the mains and its remains have been removed.

Err... where ? Theres no droppings in that pic at all (apart from all the crap on the table in the background)

Theres no way a mouse would get in it when sealed anyway.

The rat was found on the mainboard (because someone had removed the PC case). I highly doubt the rat undid the PSU screws, took off the casing, took a piss, and then put the case back on. :)

I'd almost say it was a cap exploding, but everything is there in one piece and looks fine, and no smell.

by the square bit on the cover, almost inline with your 2nd finger. mouse will fit in where the outgoing wires are, thats tons of room for mice. i have found mice inside microwaves before, they don't need much room to get in.