0 Members and 1 Guest are viewing this topic.
If you want to learn more, please visit our website SUNJ ENERGY.
If you are looking for more details, kindly visit high energy capacitor.
flashthunder
Electrolytic capacitor question
«
on: February 02, , 08:16:14 pm »
Hi, looking for input to a capacitor question. I am in the process of recapping a scope power supply. The scope is a Tektronix B and built @. Some of the electrolytic capacitors that I purchased are physically smaller than what's currently installed in the power supply. For instance, new 10uf, 100v, 105degee electrolytic capacitor is on the order of perhaps 6 or 8 times physically smaller than original. Has 30+ years of improved technology allowed for same performance in a smaller package...or should I search for a physically larger packaged cap? Thanks
techneut
Re: Electrolytic capacitor question
«
Reply #1 on: February 02, , 08:29:09 pm »
Yes the elco's are now a lot smaller. People who are restoring old equipment open up the big can capacitors, empty them and place new capacitors in them to keep the original look.
axantas
Re: Electrolytic capacitor question
«
Reply #2 on: February 02, , 09:57:58 pm »
I did restore restore/recap video recording "machines" from the late seventies, replaced about 90 capacitors and ended up in front of some quite empty pcb's - size did not matter, so I just left it the way it was. One interesting example here:
KungFuJosh
Re: Electrolytic capacitor question
«
Reply #3 on: February 02, , 11:07:08 pm »
Yeah, the size change is totally normal. One thing that annoys me is that some companies make larger electrolytics and charge extra for them to look like old style caps. Pop them open, and they're just newer / smaller caps in a larger shell. ????
"Experience is something you don't get until just after you need it." - Steven Wright
Best Continuity Tester Ever
Zero999
Re: Electrolytic capacitor question
«
Reply #4 on: February 02, , 11:31:54 pm »
Why are you recapping? It's often unnecessary to replace all of the electrolytic capacitors.
Smaller isn't always better. Smaller capacitors might have a higher ESR and also won't be able to dissipate as much heat generated by the ripple current, as well as larger ones.
If you must replace a capacitor. Choose one to match the PCB footprint, with a low ESR, high ripple current and temperature rating.
flashthunder
Re: Electrolytic capacitor question
«
Reply #5 on: February 03, , 09:37:51 am »
Thanks all...exact info I was hoping for! Zero999, I will not be replacing all caps...only those on the rails that show above ripple specs. Also, interesting about cutting the can open and installing another capacitor inside to retain original look...very clever.
Zero999
Re: Electrolytic capacitor question
«
Reply #6 on: February 03, , 03:54:09 pm »
I always aim for voltage first, i.e. it needs to be equal to or greater than the part being replaced, then pitch, but note the can must fit and check it's not too tall, and finally value. For supply decoupling, the value isn't critical. It's okay to round down a tiny bit, so use 390µF, rather than 400µF, but not much, I wouldn't normally go under 95% of the original but it's usually fine to go much larger, but I wouldn't recommend going more than double.
David Hess
Re: Electrolytic capacitor question
«
Reply #7 on: February 04, , 03:39:43 am »
Aluminum electrolytic capacitors have gotten better so the same ratings are found in smaller cases, however the smaller cases have less surface area which lowers their ripple current rating. To preserve the ripple current rating, I replace the original capacitors with higher voltage ones so that the case is the same size, or even larger if the placement allows.
The following users thanked this post: Fungus
, axantas
floobydust
Re: Electrolytic capacitor question
«
Reply #8 on: February 04, , 03:59:45 am »
My philosophy is to shotgun and replace all the PSU electrolytic capacitors based on age. At 34 years old, some Spragues and Philips caps dry out. Not all brands last the same.
Unless you want to use time in your life troubleshooting and measuring ripple, taking the gear apart repeatedly. Some caps failing can cause damage, like in the SMPS. I find it cheaper to replace all in the PSU and be done with drama.
I find the old +80/-20% tolerance spec for electrolytics now means manufacturers have it figured out. They deliver -15% consistently. I am talking Nichicon and Chemi-con are lower (rated) value than the old caps that are still good. So I upsize ~20% accordingly to match the original values.
The physical size is much smaller due to technology improving. If size is critical then higher voltage parts or long-life parts are larger.
BrokenYugo
Re: Electrolytic capacitor question
«
Reply #9 on: February 04, , 05:25:02 am »
Definitely do up the voltage rating to match case size and increase ripple rating. I've replaced 50 year old caps with smaller modern ones that ran warmer than the iffy looking original, not unacceptably warm for 105c parts, but enough to feel it and colder is always better.
I also concur with Floobydust's observation about new high grade Japanese caps always reading on the low end of tolerance. Rarely hurts to upsize a little since they were traditionally allowed +80% anyway. That will also get the case size up some.
The following users thanked this post: axantas
factory
Re: Electrolytic capacitor question
«
Reply #10 on: February 04, , 08:19:06 am »
I've seen too many capacitors from the s & early s with failed seals, that leak corrosive & conductive electrolyte over boards, for me to leave them in place. Sometimes it's not obvious there is capacitor pee until the cap is removed.
Some PSU failures caused by this, then go on to cause major damage elsewhere.
Brands that I've seen leak include; Philips, Panasonic, Nichicon, Rubycon, Chemicon, and Sprague.
Last week we had a failure of critical equipment at work, with strange fault codes & random shutdown, a Matsushita/Panasonic cap was responsible, the capacitor pee had even found it's way through a filled via to the other side of the PCB, the equipment in question dates from .
Going too small in physical size for replacements can lead to SMPS caps, with high ripple running hotter than the old ones, in extreme cases they vent, yes we had this happen at work when bean-counters choose the replacements.
Of course there are different cap technologies, that can be smaller & have lower ESR, but they come with their own failure modes.
David
« Last Edit: February 04, , 08:24:21 am by factory »
Xena E
Re: Electrolytic capacitor question
«
Reply #11 on: February 04, , 10:29:27 am »
Just a Cautionary note.
Smaller cased electrolytic caps for any given ratings can just mean that further replacement intervals may be reduced as they dry out quicker; manufacturing has gotten so good that life specs are as close to reality as posted values, and very often I have found new 10uF alelcaps claiming 10% tolerance and measuring just north of 9uF! Sneaky barstards.
*Lower ESR is not always a desirable feature*
Shotgun replacement of capacitors en masse, is a real good way of turning the job into scrap if you're not very careful.
Xena.
Messtechniker
Re: Electrolytic capacitor question
«
Reply #12 on: February 04, , 10:38:11 am »
Smaller isn't always better. Smaller capacitors might have a higher ESR and also won't be able to dissipate as much heat generated by the ripple current, as well as larger ones.
To get around this, I sometimes replace one old large (mostly dead) capacitor by two smaller capacitors in parallel. Same total capacitance of course. This helps with ESR and heat dissipation.
Agilent A, Siglent SDG X, Hameg HMO, R&S HMC , Peaktech A, Voltcraft VC 940, M-Audio Audiophile 192, R&S Psophometer UPGR, 3 Transistor Testers, DL4JAL Transistor Curve Tracer, UT622E LCR meter, UT216C AC/DC Clamp Meter
factory
Re: Electrolytic capacitor question
«
Reply #13 on: February 04, , 01:56:36 pm »
Just a Cautionary note.
Smaller cased electrolytic caps for any given ratings can just mean that further replacement intervals may be reduced as they dry out quicker; manufacturing has gotten so good that life specs are as close to reality as posted values, and very often I have found new 10uF alelcaps claiming 10% tolerance and measuring just north of 9uF! Sneaky barstards.
*Lower ESR is not always a desirable feature*
Shotgun replacement of capacitors en masse, is a real good way of turning the job into scrap if you're not very careful.
Xena.
Yes every type of capacitor has different pros & cons.
And there is risk in leaving the original caps in place too, of course they might be of a type that is OK too.
If the OP has no experience of repairing/replacing parts, then it would be wise to practice on something of low/no value, with similar double sided or multilayer boards, before working on this scope.
David
0 Members and 2 Guests are viewing this topic.
Want more information on etc battery? Feel free to contact us.
ballsystemlord
Electrolytic capacitor brands question
«
on: September 16, , 04:47:24 am »
This comes up every so often and I have searched the forums and the net with little result.
I'm looking to increase my supply of electrolytic capacitors and I'm going for the >50v variety. Of course, I'm looking at "assortments," which means I'm at the mercy of the types of assortments that people put on the net.
I've encountered only 2 brands, JCCON and JWCO. According to a US seller, JWCO is a good brand, but I cannot find any info at all about the quality of these 2 on the net. I'd imagine that no information means that they are not blowing up, but I really wonder if they're up to spec.
Do any of you have experiences with either of these 2 brands?
Thanks!
« Last Edit: September 16, , 05:11:59 am by ballsystemlord »
jonpaul
Re: Electrolytic capacitor brands question
«
Reply #1 on: September 16, , 05:40:29 am »
chinese junk
We use USA or EU made brands, EPCOS, etc
j
The Internet Dinosaur..
passionate about analog electronics since s
james_s
Re: Electrolytic capacitor brands question
«
Reply #2 on: September 16, , 05:50:00 am »
Those assortments might be ok for a quick test but they're mostly of dubious quality. Personally I like Nichicon, Rubycon and Panasonic although there are others. It's easy to make your own assortments of common values, some savings can be had if you focus on values you typically use or that are common in equipment you work on.
David Aurora
Re: Electrolytic capacitor brands question
«
Reply #3 on: September 16, , 06:42:38 am »
*snip*
Of course, I'm looking at "assortments,"
*snip*
Why?
Haenk
Re: Electrolytic capacitor brands question
«
Reply #4 on: September 16, , 06:51:59 am »
For a quick breadboard hack, they might be OK. Check them before use, though.
However I would never ever even consider soldering them into something.
If you need a cap for a project or a repair, buy them from a reputable seller. Aliexpress is not one of those
Branded caps will often be faked, most likely even on ebay or Amazon.
Downside: Branded (high quality) caps are significantly more expensive than cheap chinese ones. But consider this: The "good caps" will likely last for many years or decades, the cheap ones might fail after a short while - is it worth your time to replace them again and again, just to save a handful of bucks?
wraper
Re: Electrolytic capacitor brands question
«
Reply #5 on: September 16, , 07:03:58 am »
JWCO is cheapest garbage which in my limited experience are not reliable. The only reasonable way to use them is in low stress circuits with no heat present. Never seen JCCON but they do not even have a website.
wraper
Re: Electrolytic capacitor brands question
«
Reply #6 on: September 16, , 07:13:07 am »
If you want something cheaper but still decent quality, buy Samxon, Samwha, SAMYOUNG, Lelon, Yageo, Jamicon (aquired by Yageo), Elite, L-tec, Hitano. Of course Rubycon, Panasonic, Nippon/United chemi-con, Nichicon, Elna are the best but very expensive too. But don't just look on the brand, there are many different series which differ in lifetime and acceptable stress a lot.
« Last Edit: September 16, , 07:35:03 am by wraper »
The following users thanked this post: ballsystemlord
strawberry
Re: Electrolytic capacitor brands question
«
Reply #7 on: September 16, , 07:51:50 am »
why capacitor assortments exist : to get rid of junk for higher price
1: I expect life to be short h max (will get dry faster)
2: on ebay and aliexpress chinese are really good at repackaging component (even for the cost of some cents)
3: cheap/shady components are good for breadboard and blowing up some components for fun
Re: Electrolytic capacitor brands question
«
Reply #8 on: September 16, , 07:07:23 pm »
Good grief, caps are cheap enough, even the good ones. Make up your own assortment of values you'll actually use and buy 10 or more of each. Buy Panasonic, Rubycon, United Chemicon, Illinois, Elna or Nichicon. Buy from Digikey, Mouser, Allied, Newark, Avnet, Future or Arrow. Don't buy junk!
The following users thanked this post: David Aurora
, TomWinTejas
ballsystemlord
Re: Electrolytic capacitor brands question
«
Reply #9 on: September 17, , 02:03:22 am »
Quote
Why?
I was under the understanding that building your own assortment of components was more expensive than buying one pre-made due to the seller being able to do bulk purchases and then sell them in smaller quantities to us.
Also, although I could certainly just buy exactly the values I need at the time I need them, I'm then at the mercy of shipping time and shipping charges.
The following users thanked this post: TomWinTejas
ballsystemlord
Re: Electrolytic capacitor brands question
«
Reply #10 on: September 17, , 02:05:31 am »
Just to be clear, I'm not saying "I will buy junk." that's why I'm asking, "Are these brands junk?"
TimNJ
Re: Electrolytic capacitor brands question
«
Reply #11 on: September 17, , 04:22:21 am »
There is theoretically a shelf life issue with electrolytic caps though I am not sure how serious of an issue that really is. If you have an LCR meter you can always check that the capacitance and ESR makes sense before you install it in a circuit.
Anyway, partly for that reason, I only keep a small stock of electrolytics. Plus, often electrolytics are used in applications where absolute capacitance is not critical, so there’s not much need to stock tons of values. If you do need something special, just order it.
10-uF / 25-50V in 1, 2.2, and 4.7 increments is probably enough. Panasonic FR or similar is a good all around cap to have around. Not expensive. I would not bother with the super cheap stuff.
« Last Edit: September 17, , 04:25:41 am by TimNJ »
The following users thanked this post: EEVblog_Fan
TimNJ
Re: Electrolytic capacitor brands question
«
Reply #12 on: September 17, , 04:23:46 am »
Double posted somehow?
Siwastaja
Re: Electrolytic capacitor brands question
«
Reply #13 on: September 17, , 08:21:11 am »
I was under the understanding that building your own assortment of components was more expensive than buying one pre-made due to the seller being able to do bulk purchases and then sell them in smaller quantities to us.
True if you need all those parts, but the problem with assortments are, you are never going to use 95% of the parts.
Get assortments with gazillion of different resistor values for example, because during prototyping etc. you need all kind of resistor values and can't predict what exactly.
But electrolytic capacitors are not like this. When you need one, you know which one you need, and you probably want a good quality part. Shop when necessary. It will end up cheaper.
Besides, when you buy parts for your projects and always order a few extra part, you start developing your own stock, and what's best, the parts are usable for you; you needed them once, chances are there you will use the same parts again.
mariush
Re: Electrolytic capacitor brands question
«
Reply #14 on: September 17, , 08:34:13 am »
Those brands of capacitors would probably be fine for use with low frequency stuff, like on the input and output of a linear regulator, or for some RC circuit, maybe some Arduino stuff, smoothing out some fan.. stuff like that... but I wouldn't use them in high switching frequency circuits... they'd probably be ok for prototyping in a pinch, but not for something you'd actually use or sell.. wouldn't use them for example when making a step-down or step-up dc-dc converter, led drivers, or when repairing a LCD monitor or some other power supply.
On electrolytic capacitors, I prefer Nichicon, United Chemi-Con, Rubycon, Panasonic, Elna ... Samxon and Teapo are not bad, not in the same league but above the "OK brands" in my opinion. Wurth electronic apparently makes good capacitors but I never used them.
Some other OK brands would be Aishi, Elite, Samwha, even Jamicon is used a lot in some devices...
There's some brands of polymer capacitors which are OK, like X-Con (if my memory is correct they're the Samxon solid/polymer capacitor division), Kemet makes a lot of solid/polymer capacitors as well and depending on how well stocked that part is they can be quite cheap if bought in volume (as in at least 25-50 pcs)
There's less popular brands like Kemet and Vishay and Epcos , they're just less popular in stuff I deal with (mass produced electronics like motherboards, monitors, switching power supplies).. maybe they're good in some applications or for some niches but I don't have experience with them
HalFoster
Re: Electrolytic capacitor brands question
«
Reply #15 on: September 17, , 12:07:42 pm »
Personally, I always get Nichicon in a 105° rating - although any of the other major brands (Wurth, UCC, Vishay, CD etc) are pretty much just as good. Panasonic has a good reputation but to me they seem to exaggerate their specifications somewhat. As was mentioned, don't try to get all values - in 99% of the cases, a 470uF can be used in the place of a 100uF - although generally substitute with a higher value. There are, of course, exceptions to this but knowledge of those comes with experience - and asking questions of those that have already "been there, done that" such as on these forums.
Hal
--- If it isn't broken... Fix it until it is ---
The following users thanked this post: ballsystemlord
Re: Electrolytic capacitor brands question
«
Reply #16 on: September 17, , 04:39:29 pm »
Anything under 1 or 2 uF you'll probably use a film. I try to have 4.7, 22, 47, 100, 220 and 470 uF on hand. Even that's more than you likely need- ditch the 22 and 100 if you like. Circuits aren't that fussy. Larger values I order special. Age matters, but storage for a few years is no problem. I bought many caps surplus decades ago and do have to toss a bag or two every now and then. The ones that go bad are usually the 2nd tier brands. I have hundreds of axial uF 25V Daewoo caps (sold by National Capacitor Corp.) that have gone bad. Don't kid yourself that reforming will help. When they get a couple decades old, they're usually junk. A good reason to avoid NOS parts from eBay and such. More recent parts from Digikey have been no problem.
EEVblog_Fan
Re: Electrolytic capacitor brands question
«
Reply #17 on: September 20, , 04:14:40 am »
Just a stupid remark; Since mostly very old stock electrolytic caps die out even before you even use them,why Is It there is no label marked on them stating the date of manufacture?? I know this too can be faked.
The following users thanked this post: ballsystemlord
inse
Re: Electrolytic capacitor brands question
«
Reply #18 on: September 20, , 06:27:10 am »
Store in a cool and dry place.
Best before…
The following users thanked this post: ballsystemlord
Haenk
Re: Electrolytic capacitor brands question
«
Reply #19 on: September 20, , 01:00:24 pm »
Just a stupid remark; Since mostly very old stock electrolytic caps die out even before you even use them,why Is It there is no label marked on them stating the date of manufacture?? I know this too can be faked.
Often there is - at least on larger caps. Sometimes it's a real datecode, sometimes a cryptic batch number/datecode.
For commercial use, there is a strict shelf life (the package has a date of manufacture, so that can be easily checked) - for private use, the caps are usually good for several years.
The following users thanked this post: EEVblog_Fan
BrokenYugo
Re: Electrolytic capacitor brands question
«
Reply #20 on: September 20, , 08:40:29 pm »
Some of those cheap assortments have been known to not even make their stated voltage ratings, like put 16V across one marked 16V and it'll blow in seconds.
ballsystemlord
Re: Electrolytic capacitor brands question
«
Reply #21 on: September 20, , 09:41:00 pm »
I think a date of expiration would also be good.
But I have noticed that more parts expire than just electrolytic capacitors. For example, IIRC, laser range finding chips also have an "expiration" date.
The following users thanked this post: EEVblog_Fan
rdl
Re: Electrolytic capacitor brands question
«
Reply #22 on: September 21, , 04:31:46 am »
I don't think I've ever seen a part with an expiration date, but packaging often does because of moisture absorption concerns.
David Aurora
Re: Electrolytic capacitor brands question
«
Reply #23 on: September 22, , 02:09:48 pm »
QuoteWhy?
I was under the understanding that building your own assortment of components was more expensive than buying one pre-made due to the seller being able to do bulk purchases and then sell them in smaller quantities to us.
Also, although I could certainly just buy exactly the values I need at the time I need them, I'm then at the mercy of shipping time and shipping charges.
False economy if you end up with shitty caps and values you never use though.
I think the best approach if you want to be prepared is just purchase high quality parts based off what you use most. For example, have I needed an 82uF/400V cap before? Yeah, once I think? Am I going to want more of them taking up parts bins? God no! On the other hand, if you need a 22uF/500V axial cap or an 100nF/50V cap I've got buckets of them.
If you haven't got enough jobs under your belt yet to know what you use most just make an estimate off your last couple projects and the next one you're planning and round up a little (e.g. if you need 7 x 1uF/50V buy 10). If you do things this way it's also easier to pad orders for free shipping etc. Like if my Mouser/E14/Digikey/(R.I.P RS Components) cart is sitting 12 bucks below the free shipping threshold and shipping is $15 I'm damn sure making the 5 pack of 47nF caps I need a 10 pack, and throwing a pack of my most used fuses and a few TL072's in there until I cross the threshold.
DavidKo
Re: Electrolytic capacitor brands question
«
Reply #24 on: September 23, , 07:45:50 am »
For testing I simply use desoldered caps. If you have enough free space, store the old PCBs. If you do not have the space and you have time desolder the parts from PCB.
For new designs I order parts from mouser, tme, etc. Usually it takes 3-4 working days to get parts (even when mouser ships the parts from US).