PSU badcaps!

[gustie]

found some naughty caps in an old PSU

ones vented slighty - 3 bulging

another looks like its covered in solidified honey! dunno if this is a resin or a vent??

will add pics soon...

what damage can a duff PSU like this cause to the rest of my system IF i used it?

[KeriJane]

Re: PSU badcaps!

Hi Gustie!

Ummm.... we have a whole section of the forum dedicated to PSU troubles, particularly bad caps. It's under "Power Supply Design and Troubleshooting".

The Resin that you see is probably glue. They use glue to hold all the parts in place prior to soldering. You can expect to see big gobs of it all around caps and other components that might fall off when the board is inverted for soldering.

How much damage can a PSU with vented caps cause?

LOTS! (eventually, that is)
It can literally destroy anything plugged into it. And maybe a few things indirectly like memory chips or CPUs.
Most often a hard drive will fail first because they have little protection in the form of their own capacitors, chokes, etc. Although motherboards and video cards usually do have their own filtering / regulation sections they can be damaged too, particularly the motherboard .

The sad thing: The world is full of people that think because the PSU lights up and maybe passes a simple voltage check that it's FINE and NOT THE PROBLEM and that Brand X,Y or Z hard drives or motherboards are no darn good because they just keep going bad!

Oh Well.
Have Fun!
Keri

[PM650]

Re: PSU badcaps!

For a few minutes, probably nothing permanent. Anything longer is debatable and not worth trying. Electrolyte leaking won't look like a cap dipped in honey, electrolyte isn't too viscous and usually evaporates, leaving a residue.

[gustie]

Re: PSU badcaps!

thanks

i thought the "honey" stuff was a glue or resin - a few blobs fell out when i opended the case too



u can see one cap venting slightly ^^^ is this causing trouble in this state?

[KeriJane]

Re: PSU badcaps!

Hi Gustie!

Yes, almost certainly.
Venting, even "slight" venting indicates a catastrophic failure of the electrolyte. Electrolytic Capacitors don't do very well without the electrolyte!

It would be fun to hook an Oscilloscope up to that thing or even better a load tester like JonnyG uses... that's the only way to visualize the trouble that that cap is almost certainly causing.

If you intend to use that PSU it would be a good idea to replace all of the secondary caps with suitable "LOW ESR - High Ripple Current" caps.

Have Fun!
Keri

[gustie]

Re: PSU badcaps!

i might keep this PSU for practice then

[Scenic]

Re: PSU badcaps!

lol.. i remember one of jonnygurus reviews.. (bargain psu roundup AFAIR)

where a failed viva cap in a psu (secondary side) caused 400mv ripple!

edit: here it is... (scroll down to the Topower unit)

http://www.jonnyguru.com/modules.php...Story4&reid=71

edit2: on the next page there's a pic of both the bulging input cap and the failed output cap...



lol i just noticed the path to the pic is /NDReviews/images/Ghetto