Leaky capacitors in a brand new power supply - Page 1
Forum section: electronics / repair

author: compet17
author_rank: Regular Contributor
timestamp: February 25, 2015, 08:27:45 pm
content: Yesterday I found a power supply, newer used, fresh out of the box with leaky capacitors! I mean it was already defective when shipped!Then I took a second identical one from the shelf and shot this video:Is this unbelievable or what?They are selling defective stuff! Maybe that cap has blown during the tests or they recycled old crap. I haven't checked if the capacitor was installed with correct polarity. I was so disapointed that I threw it directly into the recycle bin.It is so sad what crap is produced every day

author: edpalmer42
author_rank: Super Contributor
timestamp: February 25, 2015, 08:38:53 pm
content: I know that sometimes a store will re-shrinkwrap a returned item after inspecting it. This may have been a shady customer who took out the new power supply and returned an old one. Can you see any date codes on the components?Ed

author: PA4TIM
author_rank: Super Contributor
timestamp: February 25, 2015, 08:48:22 pm
content: The replacement caps are more expensive as this psu. Better buy a good one with waranty.

author: compet17
author_rank: Regular Contributor
timestamp: February 25, 2015, 10:00:56 pm
content: I certainly will not repair those, it's not worth it. Who knows what else will fail next....I don't believe the bad customer theory because I had 2 identical units, each one with the same cap blown. Neatly packaged and absolutely clean. These P.S. have never been used since production (possibly 10 years ago).

author: rdl
author_rank: Super Contributor
timestamp: February 26, 2015, 05:17:30 am
content: Quote from: compet17 on February 25, 2015, 10:00:56 pmAre you saying these are 10 years old, but you're just now opening the boxes?

author: wraper
author_rank: Unknown
timestamp: February 26, 2015, 07:56:29 am
content: Sometimes electrolytic capacitors will bulge and potentially leak if stored for a long time without applying any voltage on them. Actually if it was powered time to time, it could save this capacitor. And this obviously is not "new" but "new old stock". And exceeded it's shelf life a long time ago. BTW this is not worst construction, it even have mains filtering unlike many others.

author: macboy
author_rank: Super Contributor
timestamp: February 26, 2015, 01:41:58 pm
content: Quote from: compet17 on February 25, 2015, 10:00:56 pmIf these el-cheapo power supplies were actually manufactured that long ago, then there is a good chance that they suffer from the infamouscapacitor plague.

author: nctnico
author_rank: Super Contributor
timestamp: February 26, 2015, 02:12:00 pm
content: Quote from: macboy on February 26, 2015, 01:41:58 pmIMHO it's worth replacing the capacitors. Last weekend I replaced a bunch of leaking capacitors from the motherboard of an old Dell PC I'm still using as a fileserver because it started to have random crashes.

author: PA4TIM
author_rank: Super Contributor
timestamp: February 26, 2015, 02:55:26 pm
content: Normaly caps can pop when the dissipate to much, they get hot, expand and pop open. The dissipation can be caused bij to much DC leakage or dielectric loss, ESR etc. If they are not used for a long time, like 10 years, the caps lose most of their oxide layer. And without that you have a problem if you not reform the cap before use.As far as I know it can not pop new in the box. It will only pop if you use the psu.So, if you found the popped cap before you powered it, it was not new. If it bpopped after some use, it is your own fault, never power up old stuff like this whitout reforming the caps. If they used very good parts and a good design there is a change you have luck but if it is china crap it will fail soon.

author: wraper
author_rank: Unknown
timestamp: February 26, 2015, 05:50:51 pm
content: Quote from: PA4TIM on February 26, 2015, 02:55:26 pmNope, look on the picture:

author: SeanB
author_rank: Super Contributor
timestamp: February 26, 2015, 06:23:15 pm
content: Electrolytics do go bad from old age, especially if they are a cheap off brand one. They can suffer from the electrolyte degrading, generating pressure and blowing the unit up just sitting in storage. If they were made with the stolen electrolyte formula, that did not have the right stabilisers added to it to give long life, the acid it degrades into will attack the aluminium ( by design, to etch the foil during assembly to fix any scratches during rolling and mounting but the stabilising additives react slowly to neutralise it for long life) excessively, giving rise to internal pressure that will at best blow the vent, or blow the can off.

author: GreyWoolfe
author_rank: Unknown
timestamp: February 27, 2015, 01:20:56 am
content: Of course they are going to fail. They are Capxon or Crapxon as badcaps.com calls them. If I saw them in a new device, I would return the device. If they are using shoddy caps, where else did they use poor quality components. Replace them and move on. Hopefully, the psu will be fine after the cap replacement.

author: wraper
author_rank: Unknown
timestamp: February 27, 2015, 03:26:35 am
content: Quote from: GreyWoolfe on February 27, 2015, 01:20:56 amThe sad part is you likely need to urgently return every 3rd-5th device in your home.

author: PA4TIM
author_rank: Super Contributor
timestamp: February 27, 2015, 07:13:28 am
content: Quote from: SeanB on February 26, 2015, 06:23:15 pmThanks, that is why capacitors are my favorite metrologic subject. They keep surprising me. I think I'm gonna buy some electrolityc c(r)aps and "analyse" them. (electronic and mechanical, I'm chemical-retarded)

author: SeanB
author_rank: Super Contributor
timestamp: February 27, 2015, 06:18:12 pm
content: Quote from: PA4TIM on February 27, 2015, 07:13:28 amBuy them? Go out on rubbish day ahead of the bin truck by a street or three and get them free. You just have to fight the Gypsies and my in laws ( Dutch) who made money driving a truck around on rubbish day and collecting old furniture that they then took by ferry to the UK to sell as antiques. They did a good amount of that.

author: PA4TIM
author_rank: Super Contributor
timestamp: February 27, 2015, 06:47:15 pm
content: Rubbish day ? We have to bring things that do not fit in the trashbin to the landfill. And there we need to sort it. (metal, glass, garden-trash, electronics, construction stuff, chemical stuff etc)Those grey things are the lids of the container. They are at a lower level so you can dump the trash more easy.Officially you are not allowed to take stuff from there. I think that's why your inlaws are movedI have some bad caps. I solder them on pcb strips and write down the specs. I use them to test/compare LCR meters.http://www.pa4tim.nl/?p=3331measuring bad capshttp://www.pa4tim.nl/?p=1385DC leakage testshttp://www.pa4tim.nl/?p=3775ESR related things