Weird/What cap is that?  - Page 1
Forum section: electronics / general

author: uridium
author_rank: Newbie
timestamp: October 19, 2014, 12:43:54 am
content: G'day,Trying to ID a cap in a power regulator setup on a board. Google and datasheet searches are not turning up anything unfortunately. There's about 20 of them in front of chokes. It's an aluminum can with the values:5KS32(*) 8203VAt a guess I'd wager the K means 10% tolerence, and 3volt sure. 820? The logo is where the (*) is "C" letter with a dot in the centre.Anyone have a clue? I really appreciate any feedback. Thanks.Best Wishes,Al

author: wraper
author_rank: Unknown
timestamp: October 19, 2014, 12:54:30 am
content: You'd better post a photo. Suppose those are conductive polymer capacitors, they fail rarely if you want to replace them by chance. Failure mode usually is a short, not capacitance loss. 820uf 3v, isn't that computer motherboard?

author: uridium
author_rank: Newbie
timestamp: October 19, 2014, 01:13:12 am
content: Hi Wraper,Thanks for the response. I was wondering about attaching a pic.Here's the offending item:Hope this works (I've not posted an image here previously). Oh nifty, it did.Thanks,Al

author: wraper
author_rank: Unknown
timestamp: October 19, 2014, 08:21:34 am
content: Weird color reproduction. If marking is not black, then it is 100% conductive polymer (solid capacitor, solid electrolytic capacitor). If black there is a small chance that usual electrolytic but they don't come in such a low voltage AFAIK. And there should be a visible vent on top for regular electrolytic.

author: SeanB
author_rank: Super Contributor
timestamp: October 19, 2014, 08:26:25 am
content: You never met Sony caps, which are available in 3V ratings.

author: Kjelt
author_rank: Super Contributor
timestamp: October 19, 2014, 10:51:29 am
content: Quote from: wraper on October 19, 2014, 08:21:34 amI have never seen it on top for SMD mount electrolytics, probably due to the reflow temperature rupture possibility they have designed it in the bottom of the casing where it stays cooler but that is just a guess from my side.So SMD bottom stays cool so vent in bottom, and through hole the top stays cool so vent is in the top.My guess indeed a normal SMD mount electrolytic 820uF / 3V from the KS series but I can't find the manufacturer. All A brand manufacturers the KS series is through hole.You can replace it with a SMD or normal through hole electrolytic 820uF /6V3 or 10V or what you can get or have in stock and that will fit the mechanical space.First measure the voltage that is on the pads, it should be < 3V otherwise come back here and report since then we have a mystery.

author: wraper
author_rank: Unknown
timestamp: October 19, 2014, 11:32:32 am
content: Quote from: Kjelt on October 19, 2014, 10:51:29 amSeriusly? And it's not SMD BTW. As of cooler bottom, do you think that internal pressure in the bottom and top of the capacitor is any bit different to that matter.

author: Kjelt
author_rank: Super Contributor
timestamp: October 19, 2014, 12:09:13 pm
content: Ah ok than that settles it, my guess was wrong

author: uridium
author_rank: Newbie
timestamp: October 19, 2014, 12:15:39 pm
content: Wow! Lots of replies since I last checked a couple of hours ago!Thanks guys.Working on the earlier comment by wrapper that it's 820uF @3v I've de-soldered two others and measured the decay at 2.91v and given my timing 'guesses' it's calculated to ~910-930uF so I took a punt and ordered some 820uF@6.3v capsThanks for the help guysShall report back.Also.. it is black. My craptastique camera was having a Pentax moment.Al

author: wraper
author_rank: Unknown
timestamp: October 19, 2014, 12:43:06 pm
content: If you will replace solid polymer one with electrolytic, i will die very fast BTW if the circuit will work normally at all. You can crack open one of them, that will tell you 100% which type is it. Also replacing working polymer capacitors is completely useless unlike with electrolytic ones. In my experience electrolytic capacitors don't have a vent only if they are low capacity or made a few decades ago.

author: Kjelt
author_rank: Super Contributor
timestamp: October 19, 2014, 02:20:13 pm
content: Well it is not a vent but more an intended weakness in the casing so with overpressure it will rip open with less violence as if there was no weakness. Without weakness you would have an explosion of the entire casing.

author: uridium
author_rank: Newbie
timestamp: June 06, 2015, 01:30:28 am
content: Hi Wrapper,I keep thinking about your comment regarding it dying very quickly. I'm a bit of a n00b. Any reading you can point me towards regarding the why on this?Thanks again for the advice. It was electrolytic and the 6.3v are still working nearly seven months later.Al

author: c4757p
author_rank: Super Contributor
timestamp: June 06, 2015, 01:40:22 am
content: Polymer capacitors have very low loss - even quite high currents through them don't really heat them up much. As such, if a device is using polymer capacitors it's because itexpectssuch high currents. Aluminum electrolytics have higher series resistance and need to be larger or used in larger numbers to handle that.

author: JuKu
author_rank: Frequent Contributor
timestamp: June 09, 2015, 10:40:53 am
content: There are other reasons than high current capability why polymers might be a good choice. In signal path, low losses mean the same capacitance on low and high voltages, which translates to low distortion on filter circuits. Also, their tolerances tend to be better (manufacturer and type dependent, of course). When you really need 820u (and 720u will not do), you need to look away from electrolytics.