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Electrolytic Capacitor kit for repairing TV, Laptop etc?
Posted by
anoeev
on 29 Jan, 2021 20:59
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#1 Reply
Posted by
Zero999
on 29 Jan, 2021 21:34
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No, I wouldn't recommend it. You don't know what crap it contains. It's worth spending extra on decent electrolytic capacitors. Cheap ones often fail and have high (ESR) effective series resistance.
A decent kit is good for prototyping, but no good for repairs. There are too many possibilities, regarding temperature & voltage ratings, value and very importantly case size.
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#2 Reply
Posted by
anoeev
on 29 Jan, 2021 22:36
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Which Capacitors would you recommend? I've found kits of several capacitors from 1uF to 1000uF that are more expensive, but i suspect they are still from China just sold under another name.
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#3 Reply
Posted by
james_s
on 29 Jan, 2021 22:38
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I keep a few common values around for projects but for repairs I usually buy what I need when I need it so I have fresh parts from reputable suppliers. Most of those cheap capacitors from China are garbage, I cringe whenever I encounter something someone has "recapped" by replacing a bunch of older but good quality parts with the cheapest new junk around. There are many good capacitors out there but my personal favorites are Nichicon, Rubycon and Panasonic. I've had good luck with all three.
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#4 Reply
Posted by
BrokenYugo
on 29 Jan, 2021 23:17
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Assuming we aren't talking about 40+ year old equipment, most failed electrolytic caps seem to be in positions where a low ESR cap is required, and/or high temp/high hour. And if we are talking old stuff you probably want something that will last (high temp/high hour) anyway. These are relatively expensive parts you aren't going to find in a big cheap assortment kit in acceptable quality like you can with resistors, small signal transistors, etc. As mentioned the cheap kits are going to be ok for playing around building your own stuff though, especially if you have some means of testing them (A cheap "transistor tester" component tester beats nothing).
For repair work it's best to buy as needed from reputable vendors (in the US that'd be Mouser, Digigkey, etc.), maybe build up a small inventory for substitution. Barring that I'd rather use tested parts pulled from scrap than eBay grade stuff.
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#5 Reply
Posted by
TimNJ
on 29 Jan, 2021 23:24
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Not sure what electronics distributors are available to you in Norway. I think I remember that, for some European countries, might make more sense to buy from Chinese distributor as opposed to getting from the US, etc. You have TME though, right?
Murphy's law will usually get you. You won't have the value you want/need, or you'll have it in the wrong size, etc. I wouldn't bother maintaining a stock on the basis of "order once, set for life".
For replacing caps, it's important to match the ESR of the cap you are replacing. i.e. Check the datasheet of the cap you are replacing and aim to replace with similar or slightly lower ESR. Also, be mindful of the endurance rating. i.e. Stay away from 1,000 or 2,000 hour rated caps. Recommend to use 5,000 - 10,000 hour caps if you can get them.
As others have said, Nichicon, Rubycon, United/Nippon Chemi-con, Panasonic are all good. But, you'd honestly be just as fine with reputable Chinese/Taiwanese brands like Samxon, Taicon, Aishi, or Lelon, provided you pick a decent series from them...which again, goes back to selecting proper ESR and endurance rating.
But, just buy them each time you need them, and maybe buy a few extra each time. You might get lucky next time around, with something you bought before.
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I would avoid capacitor kits from China like the plague!
There is a reason you are replacing the caps to begin with, it is because they came from the same shop in a back alley in the Shenzhen market.
The only capacitors to this day that can be generally trusted come from Japanese brands: and the Chinese love to copy them!
So if you buy Rubycon, Nichicon, Sanyo/Suncon or United Chemi-Con and they come from China via Aliexpress I can guarantee you they have a high percentage risk of being counterfeits!
There are some small stores available to you, if you don't wanna buy from Elfa (that sadly moved their warehouse away from Sweden) or TME as was suggested or Mouser then you can try Electrokit.
It is a small Swedish reseller that stocks some common parts otherwise sold by Elfa and the likes, though for capacitors their stock is quite limited.
I would just do as was suggested and buy from the large trusted sources and each time you need buy a few extra, most give you free shipping if you spend like $50.
So it is a good excuse to buy some extra caps
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#7 Reply
Posted by
Siwastaja
on 30 Jan, 2021 17:41
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Capacitors fail because the original designers failed to design correct capacitors in. They were professionals, maybe with hard-to-meet cost constraints, but professionals nevertheless. You need to be better.
Replacing with random parts will result in a "repair" which will likely last for much shorter time than the original. OK in a pinch if you just need some weeks of operation out of a device you are going to replace anyway.
You need to understand the circuit and why the part failed, what were the ratings and the quality of the failed part, then substitute with something better suited.
Generally, if the capacitor is in a high ripple current switch mode converter and the original part is a no-name low-cost brand, replace with Panasonic FR, FM series or something similar, with similar or slightly higher ripple current ratings.
If the original part was already a good known brand, then the original problem likely wasn't low quality part, but choosing a part with ripple current or temperature rating too small, then you need to substitute with one having better ratings, i.e. higher ripple current rating, higher lifetime and/or temperature rating.
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#8 Reply
Posted by
MathWizard
on 30 Jan, 2021 18:52
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Hi DIY folks
I'm looking for a basic Kit of electrolytic Capacitors to learn to fix things such as TV, Radio, laptops.
I was wondering if a basic 1uF-1000uF kit from aliexpress is alright or will the quality be so bad that they won't work as replacement electrolytic capacitors?
A big pack could last many years and be used for DIY projects.
https://www.aliexpress.com/item/4000579643509.html?spm=a2g0o.productlist.0.0.14c321c3mU9mMB&algo_pvid=4b06afbd-d6b2-4dee-935d-2149cc374a89&algo_expid=4b06afbd-d6b2-4dee-935d-2149cc374a89-5&btsid=0bb0624716119534723722257e4f74&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_
Let me know your thoughts and also which set you recommend
Electrolytic capacitors probably won't be the only type of capacitor i would need.
To get you out a of a jam, I'd say most cheap capacitors, as long as they are rated for what their label says......they should be ok for short term, especially ceramic caps, and low power caps, and DC blocking caps, etc.
But for long term replacements in things like a Switch Mode Power Supply, like in computers, TV, pretty much everything these days that's low power consumer electronics, etc...or high voltage tube radios/etc.....I'd say then it's much safer to order more expensive brand name caps, with the true proper spec's for the job.
I have some cheap caps of most types, a few nice caps from salvage that are still good, and hardly any caps that I could vouch for tho, if they wanted top join the Mafia I guess.
Do I regret buying cheap caps from ebay over the last few years ? I only remember blowing up 2, and that was by mistake. But that was just VERY VERY VERY low power stuff, like a few Watts. So no, I guess not for breadborading and the odd repair.
I don't have any electrolytic cap's I trust for any length of time in a computer SMPS, or TV/monitor SMPS. And hardly have any caps I'd call accurate for timing.
If the cap is in a high power, and/or /high temp/frequency setting, and it's an electrolytic cap, then get something brand name for long term confidence.
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#9 Reply
Posted by
Renate
on 30 Jan, 2021 19:09
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#10 Reply
Posted by
james_s
on 30 Jan, 2021 19:13
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To get you out a of a jam, I'd say most cheap capacitors, as long as they are rated for what their label says......they should be ok for short term, especially ceramic caps, and low power caps, and DC blocking caps, etc.
But for long term replacements in things like a Switch Mode Power Supply, like in computers, TV, pretty much everything these days that's low power consumer electronics, etc........I'd say then it's much safer to order more expensive brand name caps, with the true proper spec's for the job.
I have some cheap caps of most types, a few nice caps from salvage that are still good, and hardly any caps that I could vouch for tho, if they wanted top join the Mafia I guess.
Do I regret buying cheap caps from ebay over the last few years ? I only remember blowing up 2, and that was by mistake. But that was just VERY VERY VERY low power stuff, like a few Watts. So no, I guess not for breadborading and the odd repair.
I don't have any electrolytic cap's I trust for any length of time in a computer SMPS, or TV/monitor SMPS. And hardly have any caps I'd call accurate for timing.
If the cap is in a high power, and/or /high temp/frequency setting, and it's an electrolytic cap, then get something brand name for long term confidence.
I've repaired a lot of CRT monitors for vintage arcade games and for many years there have been cap kits on the market for specific monitor models so it's very common to find monitors that have had the whole set replaced with what tend to be the cheapest parts available at the time. I've seen lots of cases where the original capacitors were replaced when the monitor was 25-30 years old and then after just a few years of home use there were bad capacitors again. That's what made me realize that a lot of the cheap electrolytic capacitors are just junk.
I agree about the ceramic though, I have not experienced the high failure rate with cheap ceramic capacitors, and the cheap film capacitors seem ok too.
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#11 Reply
Posted by
wraper
on 30 Jan, 2021 19:17
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For replacement parts, especially on stuff that you're going to repair for other people I don't like to screw around with iffy components.
I bought this electrolytic assortment from Digi-Key with caps from Panasonic.
https://www.digikey.com/en/products/detail/panasonic-electronic-components/M2-KIT/4383781
(Funny, they don't seem to have a price on it now.)
When I use some of the caps I just put some more on my next order.
Such kit is pretty much pointless for repairs. You'll be quite lucky if there will be something, and especially everything you need for actual repair. Not to say it does not even contain low ESR capacitors which are a must for repair of TV, monitors and similar.
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#12 Reply
Posted by
Zero999
on 30 Jan, 2021 19:22
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To put this into perspective, try searching TME, RS Components, or Farnell for a 100µF 400V capacitor. Look at how many options there are, in terms of physical dimensions, for a start. There have been plenty of occasions when I've had the correct value and voltage in stock, but it's the wrong shape to fit. Sometimes I can just bodge it on with wires, but quite often it just won't fit in the case. My capacitor kit is primarily used for prototyping, hardly ever for repairs.
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#13 Reply
Posted by
Siwastaja
on 30 Jan, 2021 19:27
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Kit wouldn't make any sense; you would need say some 20-30 different parts about 5-10 pcs each to be able to actually repair something. If decent quality, such kit would cost way more (at least some $50 for just the parts) than paying for Digikey/Mouser postage once or twice, getting just what you need, and 99% of the parts in the kit would slowly age without ever being use.
Now, a professional repair shop theoretically could end up using the parts of such kit, but OTOH, they have no problem just ordering the correct parts when they need them, it's their core business.
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#14 Reply
Posted by
Renate
on 30 Jan, 2021 19:30
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You'll be quite lucky if there will be something, and especially everything you need for actual repair.
Gosh! I guess that I'm lucky then.
Not to say it does not even contain low ESR capacitors which are a must for repair of TV, monitors and similar.
Yes, low ESR is desirable, but since when have we raised this to a fetish?
Usually I just replace a bad cap with one of these:
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#15 Reply
Posted by
Siwastaja
on 30 Jan, 2021 19:34
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Some circuits, for example those filtering rectified 50/60Hz AC, are just fine with high ESR.
But ripple current rating is highly important for switch mode converters. With wrong type of capacitor, the capacitor can self-destruct in matter of minutes due to too much internal heating. Low-ESR types are used in such circuits. Even then, it's not enough to see a "low ESR" claim, the actual ratings need to be understood (ripple current rating in mA @ 100kHz).
This is engineering, nothing to do with "fetish". You can't eyeball it or base it on feelings, it's simple math and real physics.
Obviously if it wasn't important at all, how did the original capacitor die?
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#16 Reply
Posted by
james_s
on 30 Jan, 2021 19:41
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Some circuits, for example those filtering rectified 50/60Hz AC, are just fine with high ESR.
But ripple current rating is highly important for switch mode converters. With wrong type of capacitor, the capacitor can self-destruct in matter of minutes due to too much internal heating. Low-ESR types are used in such circuits. Even then, it's not enough to see a "low ESR" claim, the actual ratings need to be understood (ripple current rating in mA @ 100kHz).
This is engineering, nothing to do with "fetish". You can't eyeball it or base it on feelings, it's simple math and real physics.
Obviously if it wasn't important at all, how did the original capacitor die?
Any number of things could have caused the original capacitor to die, but yes you are correct. I think his point is some people don't really understand any of this, they just blindly go with low ESR capacitors because they're "better". In a lot of cases it doesn't really matter, modern general purpose capacitors can be quite good compared to what was considered low ESR or high ripple current 25 years ago but once in a while you come across something where it the choice of part is more critical.
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#17 Reply
Posted by
wraper
on 30 Jan, 2021 19:49
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Any number of things could have caused the original capacitor to die, but yes you are correct. I think his point is some people don't really understand any of this, they just blindly go with low ESR capacitors because they're "better". In a lot of cases it doesn't really matter, modern general purpose capacitors can be quite good compared to what was considered low ESR or high ripple current 25 years ago but once in a while you come across something where it the choice of part is more critical.
Nonsense. Modern general purpose caps generally are nowhere close to entry level LOW ESR and about the same as 25 years ago. Not to say that digikey kit has 85
oC capacitors. Modern SMPS almost exclusively contain LOW ESR capacitors, except high voltage cap on the primary side. If LOW ESR capacitor failed, replacing it with general purpose stuff is insane. In most cases it will last a few months or less.
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Lots of good advice here. But some needs to be taken with a bit of skepticism.
Often these failed parts are in a bit of gear that was used full time (sometimes even 24 hours a day) for decades. And often stacked with a bunch of other heat generating gear. Gear that old is unlikely to ever see that type of service again. If it will, fine, replace the electrolytics with the best you can buy. If it is a SMPS good (but perhaps not top of line caps) are warranted. But in other cases the remaining actual service life of the device may well be served with much more pedestrian parts.
Case in point. The monitor I am using now failed from bad electrolytic caps. I re-capped with a modestly priced set from Ebay (not the lowest price, but far from Rubycon prices). It has been working fine for ten years so far, which matches the performance of the original installation.
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#19 Reply
Posted by
james_s
on 30 Jan, 2021 19:59
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Nonsense. Modern general purpose caps generally are nowhere close to entry level LOW ESR and about the same as 25 years ago. Not to say that digikey kit was for 85oC capacitors. Modern SMPS almost exclusively contain LOW ESR capacitors, except high voltage cap on the primary side. If LOW ESR capacitor failed, replacing it with general purpose stuff is insane. In most cases it will last a few months or less.
I never said anything about using a cheap general purpose capacitor in a modern SMPS, and I never said it was ok to replace a low ESR capacitor with something that has a much higher ESR. There are lots of SMPS from the 80s and even 90s that do not have special low ESR capacitors in them, they just use larger capacitors and usually several of them in parallel on the output rails. Ultimately it is usually the ripple current that matters, not the ESR. Most "low ESR" capacitors have a high ripple current rating but not all.
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#20 Reply
Posted by
wraper
on 30 Jan, 2021 20:12
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I never said anything about using a cheap general purpose capacitor in a modern SMPS, and I never said it was ok to replace a low ESR capacitor with something that has a much higher ESR. There are lots of SMPS from the 80s and even 90s that do not have special low ESR capacitors in them, they just use larger capacitors and usually several of them in parallel on the output rails. Ultimately it is usually the ripple current that matters, not the ESR. Most "low ESR" capacitors have a high ripple current rating but not all.
I doubt very much that such equipment is repaired that often, unless someone is collector of physically and morally obsolete stuff. Most of it has gone to landfills a long time ago. Most of the stuff with SMPS made in last 15-20 years has LOW ESR capacitors.
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#21 Reply
Posted by
TimNJ
on 30 Jan, 2021 21:53
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Please someone explain to me how ripple current rating is not related to ESR? Endurance rating is given as: Number of hours before capacitor degrades (to some point), when operated at rated ripple current and max rated temperature.
ESR drives self heating of the capacitor can by (Iripple)^2 * ESR. Can size, specifically surface area exposed determines how well the can dissipates heat generated by the capacitor “core”. I guess in engineering terms, can size influences the thermal resistance from core to ambient.
From my understanding, the ripple current rating is derived from the ESR and size of the capacitor.
Now, there exists low ESR caps with varying endurance ratings, which is a little confusing at first glance. But, basically, as I understand it, different electrolyte formulations have different tolerance to heat. I think some of the low ESR caps with only 1,000-2,000 hour lifes are “water-based” or something like that, which allows low ESR, but dry up more quickly compared to a cap with same ESR but 10,000 life.
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Please someone explain to me how ripple current rating is not related to ESR? Endurance rating is given as: Number of hours before capacitor degrades (to some point), when operated at rated ripple current and max rated temperature.
ESR drives self heating of the capacitor can by (Iripple)^2 * ESR. Can size, specifically surface area exposed determines how well the can dissipates heat generated by the capacitor “core”. I guess in engineering terms, can size influences the thermal resistance from core to ambient.
From my understanding, the ripple current rating is derived from the ESR and size of the capacitor.
Now, there exists low ESR caps with varying endurance ratings, which is a little confusing at first glance. But, basically, as I understand it, different electrolyte formulations have different tolerance to heat. I think some of the low ESR caps with only 1,000-2,000 hour lifes are “water-based” or something like that, which allows low ESR, but dry up more quickly compared to a cap with same ESR but 10,000 life.
They are related. But it isn't a one-to-one relationship. In addition to the chemistry differences you mention there are physical choices on the dimensions of the conductors inside the case, their arrangement, seals, amount of excess electrolyte at manufacturer and more. The manufacturer should and usually does know all this and the choices they made in design and manufacture. This, and how conservatively they wish to make their claims based on market strategy determines what goes on the data sheet.
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#23 Reply
Posted by
rsjsouza
on 31 Jan, 2021 01:47
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I never said anything about using a cheap general purpose capacitor in a modern SMPS, and I never said it was ok to replace a low ESR capacitor with something that has a much higher ESR. There are lots of SMPS from the 80s and even 90s that do not have special low ESR capacitors in them, they just use larger capacitors and usually several of them in parallel on the output rails. Ultimately it is usually the ripple current that matters, not the ESR. Most "low ESR" capacitors have a high ripple current rating but not all.
I doubt very much that such equipment is repaired that often, unless someone is collector of physically and morally obsolete stuff. Most of it has gone to landfills a long time ago. Most of the stuff with SMPS made in last 15-20 years has LOW ESR capacitors.
You would be very surprised to see the vast amount of people that performs repairs in Amigas, Apples, early PCs, old monitors... All of them with ancient SMPS circuits.
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#24 Reply
Posted by
wraper
on 31 Jan, 2021 02:48
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You would be very surprised to see the vast amount of people that performs repairs in Amigas, Apples, early PCs, old monitors...
IMHO you overestimate that grossly, confirmation bias. A few enthusiasts who do that relatively often and some very rare random jobs done by others. In comparison to repairs of more modern equipment, it's just a miniscule amount. Unless person states intention to repair exactly those, it's not even worth consideration.
All of them with ancient SMPS circuits.
I did not say they don't have it.