Anyone recognize the brand of these capacitors? - Page 1
Forum section: electronics / projects

author: Chuu
author_rank: Newbie
timestamp: November 29, 2017, 04:41:56 am
content: I am currently working on building a file server, and am wondering if anyone can recognize the brand of the capacitors being used on this backplane. It isn't any that I am familiar with, and I'm a little nervous that costs were cut here.

author: floobydust
author_rank: Super Contributor
timestamp: November 29, 2017, 05:57:57 am
content: I would post your question over athttps://www.badcaps.net/forum, the guys there are very knowledgeable and recognize the logo.To my eyes, they are generic 105C chinese electrolytic caps. They are not under high stress, the ripple current (that should be) seen is the +12V rail for a HDD. Unless the rack runs hot.The CPU and other loads on the 12V rail will affect the lifetime of your PC power supply and these caps would normally help there, as they are big 2,200uF per HDD.Odds are it will arrive a different make of caps anyway.I would put in top quality Nichicon or Panasonic parts.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 29, 2017, 06:46:03 am
content: Could be Rubycon, Panasonic, NCC, or off brand, who knows?I doubt there'd be much ripple on a backplane. it's neither a power supply, nor a POL converter (...unless it is).What lifetime does the mfg spec?Tim

author: TimNJ
author_rank: Super Contributor
timestamp: November 29, 2017, 03:20:57 pm
content: 'XCON' is what they are labeled. However, they are NOT the X-CON conductive solid polymer caps made by Man Yue (Samxon).As floobydust has suggested, they are just generic Chinese caps.Off a glance, you can determine the manufacturer by looking at the top vent, at least for the big brands. Rubycon has a "K" shaped vent. Panasonic a "T" shape. Nippon Chemi-con has a "tri-spoke" vent. Nichicon has a standard "X" vent so takes a whole 3 more seconds to read marking on the side. There are a few others such as Teapo, Sanyo (RIP), and Elna which also have a distinct vent stamping.

author: Chuu
author_rank: Newbie
timestamp: November 29, 2017, 03:56:29 pm
content: Thanks for the replies. The manufacturer has no spec on them and it sounds like these are generic Chinese caps at best, counterfeit XCON at worst. I believe they are all just 25V 2200uF caps so for peace of mind I'm just going to replace them all when I get the cage.I assume there are still no solid caps at a reasonable price with such a high breakdown voltage and capacity?

author: TimNJ
author_rank: Super Contributor
timestamp: November 29, 2017, 05:12:05 pm
content: Polymer caps are useful in high stress environments like on computer motherboards. They can withstand high ripple currents and operate in hot environments, like right next to a CPU and its nearby heat-producing circuitry.These caps, on the other hand, just look like local bypass capacitors to supply high instantaneous currents to counteract the series inductance of the power supply wires etc. They likely won't be seeing lots of ripple and they likely aren't getting too hot. That said, might be worth it to replace them with a good quality replacement.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 29, 2017, 07:15:10 pm
content: Backplane capacitors are most likely irrelevant. They are there to provide some high-ESR bulk capacitance. Most ripple current flows through the caps near the SMPS switching inputs and outputs, or near the fast switching loads (CPU, GPU).Now, the caps at the power supply outputs are important, they carry the ripple of the PSU switch mode converter (and are also located near to the components that heat up in the PSU, since they areneededexactly there). Similarly, caps at the input of the local buck regulators (near CPU, for example) are exposed to high ripple currents of the said converters - and the heat, too.Backplane caps are further away and hence, carry much less ripple -> less internal heating.They are also located further away from heating components -> less external heating.Also, they are less critical to the functionality -> even if they "go bad" (the ESR rises), it's probably not a big deal.It's normal design to use lower-cost elcaps in places like this. Actually high ESR is sometimes desired.Blindly looking at all alu elcaps to asses the design quality does not work. You need to know where to look at.OTOH, if the local bypassing at the PSU output / local buck input is lacking, then these capsmightcarry significant ripple. It's impossible to say for sure.