Recapping electronics guide - Page 1
Forum section: electronics / repair

author: VEGETA
author_rank: Super Contributor
timestamp: July 05, 2025, 06:32:17 pm
content: Hello,I finally got the time to make this video:I think I listed everything one wants to know about recapping or replacing capacitors.here is a write up for recapping guide:https://thundertronics.net/blog/recapping-electronics-ultimate-guide/with links and images.good luck!

author: VEGETA
author_rank: Super Contributor
timestamp: July 18, 2025, 02:13:57 am
content: here is a write up for recapping guide:https://thundertronics.net/blog/recapping-electronics-ultimate-guide/with links and images.

author: Haenk
author_rank: Super Contributor
timestamp: July 18, 2025, 11:15:50 am
content: "Lifetime and temperature: you may see “1000 hours @ 105 degrees” in a capacitor datasheet, this is the lifetime spec which means this cap if put in a board which is 105 degrees of temperature, it can work fine for 1000 hours.Meaning, if you let it work at 52.5 degrees it will last for 2000 hours and so on. The higher the better and more robust, but also more expensive and can be bigger size."Uh, that's PLAIN WRONG. Lifetime doubles with each reduction of temperature by 10 degrees. (Rough estimate)So your 1000h cap @105oC will last 2000h @95oC, 4000h @85oC, 8000h @75oC, 16000h @65oC,32000h @55oC

author: Haenk
author_rank: Super Contributor
timestamp: July 18, 2025, 11:20:45 am
content: "1- Get the exact same capacitance value: This ensures the circuit working as it expects, with rare exceptions like power supply filtering caps where you have the room to increase the capacitance to enhance ripple filtration while not affecting the circuit."In most cases, the capacity does not really matter (unless it's needed, like in filters); remember: the manufacturer often specify them for like -20%/+100% tolerance from factory. Using newer parts often allows larger capacity using the same form factor.

author: Haenk
author_rank: Super Contributor
timestamp: July 18, 2025, 11:28:47 am
content: "do not get lead-free one as it is harder to use"not so much if using high quality stuffBe aware: mixing lead-free and leaded solder during a repair is a bad idea - the resulting mixture of solder is brittle and will fail much sooner than pure leaded/pure unleaded solder.Also be aware of your instruments, the concurrent use of leaded/unleaded is a huge no-no in commercial manufacturing.

author: Ian.M
author_rank: Super Contributor
timestamp: July 18, 2025, 11:31:40 am
content: Also, what about replacing paper dielectric capacitors like the infamous Rifa ones commonly found in line filters?

author: wraper
author_rank: Unknown
timestamp: July 18, 2025, 11:41:57 am
content: Quote from: Haenk on July 18, 2025, 11:15:50 amAlso lifetime spec is at maximum rated ripple current, not temperature alone.

author: madires
author_rank: Super Contributor
timestamp: July 18, 2025, 01:01:18 pm
content: Other reasons to replace a cap are loss of capacitance and increased ESR. And it's not just electrolytic caps, e.g. the film cap in a capacitive dropper. Age shouldn't be a reason for blind recapping. For example, I have devices with 30+ years old electrolytics which are still perfectly fine. When replacing electrolytics pay attention to the type, e.g some voltage regulators don't like low-ESR electrolytics. And there are also non-polarized electrolytics. Regarding mounting caps, if you have a cap with a smaller lead spacing than needed bend its leads in a z-shape to prevent stress on the rubber seal.

author: tggzzz
author_rank: Super Contributor
timestamp: July 18, 2025, 01:23:28 pm
content: Tant beads are not reliable; I've replaced too many that have gone short circuit.Tant beans need voltage derating by a factor of, say, 2 depending on reliability requirements.The lifetime-vs-temperature is highly suspect: it will be type dependent, it is the internal temperature not the ambient temperature, and ESR+ripple current=>power dissipation and internal temperature rise.For PSU smoothing capacitors, the ripple current rating is important. The actual capacitance is not very important, since PSU smoothing capacitors have "relaxed" capacitance specs; -10+100% is not unusual.Age is not a good determinant of whether to replace electrolytics. I have many that are half a century old and still in good condition. High ESR and low C are better tests, but cannot be done in-circuit: one leg must be lifted.You cannot say a ceramic capacitor 10uF ceramic capacitor will be 1-2uF with 12V across it. RTFM to find the manufacturer's statement. In many cases the manufacturer won't supply a derating curve, in which cases a guess is necessary. The closer the applied voltage is to the rated voltage, the more capacitance will be "lost", and the faster the "remaining" capacitance will degrade over time and temperature.In filter circuits, do not replace a capacitor with a X7R or Y5U ceramic, since they are especially non-linear.

author: VEGETA
author_rank: Super Contributor
timestamp: July 18, 2025, 03:18:39 pm
content: Quotewell, what i said is an approximation to help understand the idea that the higher the rating the better. I see many people claiming different math to be correct, so I do not know if I have to select something.the main idea i wanted to deliver is getting a higher rated cap is always a better approach. I appreciate if you have a source for those numbers so I can modify the article to correct it.Quotewell, i mentioned in the video "unless you know what you are doing" or similar statement, and gave an example of replacing a power supply filtering cap that it can benefit from being bigger size.for everything else it is safer to use the same value.Quotestill lead-free is harder than leaded, and no reason to get it unless you know your device used one.but even for simple cap replacement, you will fully clean the pads from old solder so there is no danger of mixing new one with old one.QuoteI have no experience with them.If you write a small reply here, I will add it to the article for sure.Quoteyes for sure, and I mentioned that with age they start to change their capacitance and ESR.QuoteI disagree with this, even though i fully understand your experience with your device. they may look fine but probably they derated, just not enough to cause anything. Replacing them with equally or better spec caps is always a plus.In retro gaming community, we see different devices like Super Nintendo for example, recapping it is a necessity not an option and all due to age. the caps used are very high quality and load is very minimal yet they leak. they look fantastic from the outside but when desoldering them you see the leakage underneath + worse ESR\cap rating than it should.I personallyrecapped a PSone system(the smaller Playstation 1) which was made in year 2000 (could be even more) and most capacitors were leaking from undersideand that is even less than 25 years old device using nice caps.Yes, some caps can be still good after 30 years but it is always a good practice to do a full recap with best caps types for your old devices.QuoteI mentioned this but for polymer caps. Yet, I still can't determine a way to know for sure if this cap can be safely replaced with a low esr polymer or not.my suggested way is testing + reporting back and documenting it. it is really worthy to have high quality solid polymer capsQuotehmmm yes but still not good to my taste, just get the correct capacitor form factor is always best choice. I know this sounds extra elitism but still nice to get everything right especially if you wanna do it once per 30 years xDQuoteNo, I am talking about DC bias. DC bias is related to applied voltage and I mentioned an example not a determined value.I have seen many 10uF ceramics that are specified by manufacturer to be mere 1-2 uF at 12v, but yes can be more or less. I just mentioned an example.the higher rated voltage can help but what helps more is the physical size. a 1210 10uF cap will have a better DC bias than 0603 10uF cap if all other specs are the same.takethis oneas example, it has roughly 1.7uF capacitance at 12v while it is labelled as 10uF. exactly like the example i mentioned.____thank you all for your attention and possible contribution to the guide. It really took a lot of effort from me to write and do the video.

author: madires
author_rank: Super Contributor
timestamp: July 18, 2025, 03:50:21 pm
content: Quote from: VEGETA on July 18, 2025, 03:18:39 pmI measured them with an LCR meter. They are within specs. However, from experience I know which brands or specific series are problematic, and those get usually replaced without checking each one, e.g. blue Philips or orange Panasonic. I don't blindly replace all electrolytic caps, especially when a larger cap costs 10 or 15 bucks.

author: VEGETA
author_rank: Super Contributor
timestamp: July 18, 2025, 04:47:26 pm
content: Quote from: madires on July 18, 2025, 03:50:21 pmthen you have a special case where you know exactly what are you dealing with. I find detaching cap by cap from the board and test them is even harder than recap.btw, which caps do you mean by 10-15$ per one unit? maybe you speak about very very large capacitors, but i mainly speak about regular sized and priced ones. still same concept except where you verify that they are good and have the time and effort to test each one.thanks!

author: madires
author_rank: Super Contributor
timestamp: July 18, 2025, 05:09:53 pm
content: For example, classic filter caps for audio amps, like 10 mF 63 V.

author: tggzzz
author_rank: Super Contributor
timestamp: July 18, 2025, 05:10:43 pm
content: Quote from: VEGETA on July 18, 2025, 03:18:39 pmIt isn't justmyopinion nor foronedevice.One example, have a look at TekScopes group especially for 24xx scopes. Many caps do need replacing (some before first power on), but there are an awkward pair of electrolytics that never seem to cause a problem.Another example: the axial tants in Tek 485, 1502. If you can get them they are £75 each! Being milspec helps, but certainly isn't a guarantee; I've had a pair spew acid and remove PCB tracks.QuoteEr, I too am talking about DC bias. What did you think I was talking about?QuoteIn this area it is possible to find an example to make any and every point; that isn't very helpful.If you put 10V across a 15V MLCC then - in general - you will "lose" more capacitance than 10V across a 50V MLCC. It is simply due to 66% vc 20% of the rated voltage.The size is at most aderivedissue: derating is based on % of rated voltage, not volume.

author: VEGETA
author_rank: Super Contributor
timestamp: July 18, 2025, 09:09:47 pm
content: Quotewell, i posted above about our experience in game consoles which almost all the time you need to recap based on age. and I really pointed out that some caps can be totally fine even after that age, but it is always safer to recap everything instead of desoldering them to check and then return them. even if they are fine they still got worse over time but still in the "nice" area.Quoteyou know that by your experience in that particular device. you can't say that all other situations are the same right? while you may open another device which you do not know its track record or how internals behave, thus you wouldn't be able to judge which caps need replacement, which look fine but got bad specs, which are 50% life, etc...QuoteI actually found that cap without even trying to look. I went to murata since they have those nice curves but generally I found other manufacturers provide curves in datasheets.You misunderstood me, I did not say "All ceramics which are 10uF will be 1-2uF when getting 12v", but rather made an example to demonstrate the idea itself. I could have said "22uF becoming 10uF when x voltage" or "10uF being 5uF at y voltage"... all of those are examples only, not determined rule.I did not deny your talk about voltage being effective, but rather agreed with you and do use this rule in my designs. I got lost when you phrased it as "applied closer to rated" that is all.However, I did focus more on physical size as I know this by experience when designing my products and circuits.increasing cap rated voltage will surely mitigate DC bias, as well as its size. same rating 1206 will be better than same rating 0805.what you added to my knowledge is that sentence about "closer to rated voltage" because I wasn't thinking about it from this side but rather "the higher rated voltage, the better in terms of dc bias at the same applied voltage and size".___I only mentioned ceramics because i see many people recapping stuff by massively putting ceramics instead of electrolytics without thinking. Even in a youtube video i can see that the circuit may not be ok with the ceramic! i mean, solid polymers exist, so i would use them if i wanted a solid cap which is a point i wanted to make in the video.___on another topic about ceramics dc bias but not related to recapping, I used these caps in my product:https://product.samsungsem.com/mlcc/CL31A226KAHNNN.dohttps://product.samsungsem.com/mlcc/CL21A106KOQNNN.dovery good and cheap enough, multiples in parallel with other caps (won't get into it now).So I checked them back then to precisely calculate the total effective capacitance which will happen in my buck regulator since that particular regulator has a limit to effective capacitance you must not exceed.I kept searching for caps with different sizes and voltage until I got to these 2. You can see the curves very clearly and it will tell you the value which you will get at your voltages, mine were 5v and 3.3v.

author: tggzzz
author_rank: Super Contributor
timestamp: July 18, 2025, 10:07:42 pm
content: I have little reason to doubt your experience in game systems of a certain age. If you have that restriction shown prominently on your web page, there would be nothing to discuss.But your statements are too global in the ways I and others have have indicated. As such they are not correct, and could mislead people.

author: VEGETA
author_rank: Super Contributor
timestamp: July 18, 2025, 10:18:57 pm
content: Quote from: tggzzz on July 18, 2025, 10:07:42 pmwell, my video and article were for global usage but I did point out your points as other valid cases. Thus, if you or any other user have a special case not mentioned in the video, then you deal with it as you see fit. However, for most people recapping regular equipment and regular caps, it works.always thanks for your feedback with others.If you can write a small section about any useful additions or indications, I would be happy to add them to the article.

author: jdragoset
author_rank: Frequent Contributor
timestamp: July 19, 2025, 12:15:52 am
content: I have a Philips PM 3240 stacked on top of a Hitachi V-550B as my two bench "workhorse" scopes.I keep the Phillips in sweep mode and the Hitachi in XY mode.The only cap I ever changed was a RIFA AC input cap on the Philips, just out of caution.There are hundreds of blue Philips caps in the Philips scope and who knows what in the Hitachi scope.They both work fine, PS ripple are within spec and no signs of swelling or leakage.These are +30 year old scopes.

author: VEGETA
author_rank: Super Contributor
timestamp: July 19, 2025, 12:35:48 am
content: Quote from: jdragoset on July 19, 2025, 12:15:52 amare you sure there are no leaks or swelling in any cap or under it? I mean they will work fine and even ripple can be nice but the caps might be not in best condition. this is what i find in my usual recapping tbh, the device is fantastic but when you desolder the caps you will find a surprise under it.i guess if you are sure they are fine and you do not deem it worthy to refurbish them then you are good to go.thanks

author: tggzzz
author_rank: Super Contributor
timestamp: July 19, 2025, 08:24:39 am
content: Quote from: VEGETA on July 18, 2025, 10:18:57 pmFor global usage it is misleading.I didn't spot your mentioning either your use case or other use cases in the article. I'm not going to spend 35 mins watching a video when I can, presumably, get the same information spending 2 minutes reading the article.QuoteFor people recapping old professional test equipment, some of your advice may cause more problems than the other bits cure.If you state your experience is with X, then people are able to better assess the applicabilityor otherwiseto their use case.

author: VEGETA
author_rank: Super Contributor
timestamp: July 19, 2025, 10:43:20 am
content: I do not see that it is "misleading", please show where exactly you will be mislead if you read the article? I believe I mentioned "unless you know what to do" or similar wording.

author: tggzzz
author_rank: Super Contributor
timestamp: July 19, 2025, 11:02:44 am
content: Quote from: VEGETA on July 19, 2025, 10:43:20 amPlease see the previous comments in this thread.That escape clause has little meaning, since anybody reading your article to learn about the subject willnotknow what to do.Italwayslooks good if someone limits the scope of whatever they say and/or do. When they do that I am more likely to believe they do know their subject. Contrariwise, global sweeping statements are frequently made by people who don't know their subject as well as they think they do.Yes, I do use that as a filter; it has served me well over the decades.Anyway, your choice...

author: VEGETA
author_rank: Super Contributor
timestamp: July 19, 2025, 11:10:28 am
content: Quote from: tggzzz on July 19, 2025, 11:02:44 amsome commenters had additions to the topic like paper caps or so, some others mentioned their own experience with expensive caps which did not need replacement, and i kinda agreed with them. Does not negate anything I said in the article.Also, the lifetime discussion about voltage above is not against what I said but rather a different point of view.I can't see that anything is wrong or misleading in what I said.If you wants to recap a device that does not have anything extra special, the article and video will be good. + other sources online. If you have something special it is not mentioned in the article thus you judge yourself.Anyway, nice discussing with you my friend, benefited me a lot in this thread. Thanks!

author: madires
author_rank: Super Contributor
timestamp: July 19, 2025, 12:15:17 pm
content: Just for clarification, my experience with replacing caps is quite broad. I'm the family's repair shop and repair literally everything. Besides that I design and build circuits as a hobby. Some people might think that caps are all alike. In reality caps are a complex topic on their own.BTW, the article didn't mention the (electrolytic) capacitor plague around 2000. Fixed a bunch of PC mainboards and other stuff for that reason.

author: VEGETA
author_rank: Super Contributor
timestamp: July 19, 2025, 12:29:13 pm
content: Quote from: madires on July 19, 2025, 12:15:17 pmYou are a professional repair man then, nice. I am kinda like that but on a lower scale since I am a professional engineer (instrumentation) but I design my own products and excelled at electronics more than anything (I am a Mechatronics engineer). I designedmy products(revised them) to never use elec. caps to begin with but rather ceramics and polymers with high quality. rev1 was elec. caps but rev2 and all other designs moved to solid caps all the way.you are correct, caps are not all alike and with Chinese lower quality caps everywhere, it gets worse.in my article i wanted to point out that even elec. caps are not all the same quality (lifetime,etc..), not all are the same specs (low esr, non-polarized) yet many people recap old equipment with basically any cap they found on stupid ebay!For me personally, I would rather keep the old derated and sickened good caps rather than replace them with Chinese bad quality new ones... best solution is replace them with very good quality new ones. Either best solution or no solution for me.well 2000 plague is definitely worth mentioning, will add it soon. I just wanted a practical and short (as possible) guide, well the short part obviously failed.I remember the original Xbox of all consoles suffered extra from cap plague thing. However, I do not own one so I cannot see for myself what's inside. Did you fix one of those? what is the situation with it?____A side question for you: what about hybrid polymer capacitor?I mean is it better than solid polymer? since it has liquid inside i believe it reduces its reliability since liquid in elec. caps is a major issue for leaking... I bet you saw these in your repair career.

author: madires
author_rank: Super Contributor
timestamp: July 19, 2025, 01:54:43 pm
content: Nope, just repairing stuff for the family. Can't say anything about Xbox as I didn't have any on my bench so far. Regarding hybrid polymer electrolytics, there's no general 'better' or 'worse'. It depends on the specific application which type is better suited. For example, they have a lower leakage current than polymer electrolytics, but a tad higher ESR. I don't think the hybrid design has much impact on the possibility of leaking as long as the manufacturer doesn't cheap out on the seals or the leads aren't bent awkwardly.

author: VEGETA
author_rank: Super Contributor
timestamp: July 19, 2025, 02:02:33 pm
content: Quote from: madires on July 19, 2025, 01:54:43 pmwhat i wanted to know about the hybrids is why they are considered more reliable than regular solid polymers.I get it that the liquid allows bigger capacitance vs size which is an advantage over regular polymers but not for most low voltage designs. Yes, the leakage stuff and esr you said are 100% correct but i feel like they are not in the "more reliable" category to me.by having liquid, won't it degrade over time like elec. cap? i mean after some years won't it get worse compared to regular solid polymer assuming high load.i ask you because i saw someone online doing a recap blog and he mentioned that hybrid polymers are the best ever, which i found bizarre. like why? if the circuit accepts very low esr then i go for full solid polymer and get rid of liquid stuff forever... why would i re-introduce liquid elec again while i can just not do that? I mean, using a hybrid instead of a solid polymer will not make the circuit work better since their esr is low.but about designing stuff, i always see hybrids tailored for automotive usage maybe due to their higher voltage and higher cap size vs normal polymers... but they also mention the hybrids being more reliable which i cannot understand why.

author: madires
author_rank: Super Contributor
timestamp: July 19, 2025, 02:47:44 pm
content: Could it be the assumption that a wet electrolyte implies leaking what bothers you? The majority of electrolytic caps I replace have lost capacitance or have a too high ESR, rarely any leaking (including cheap Chinese electrolytics). Solid electrolytics need a thicker oxide layer to achieve their voltage rating. And the wet electrolyte in hybrid types can provide oxygen for self-healing. But that doesn't make them better in general. The specific application determins which type to use.

author: factory
author_rank: Super Contributor
timestamp: July 19, 2025, 08:54:51 pm
content: The leaking (peeing) electrolytic capacitors seem to mostly be from the 80s & 90s, it happens with a few well known brands, they are found in some consumer electronics (including old computers) and even in some industrial stuff, at work new old stock from Panasonic, Rubycon & Frako have been found leaking in storage*, once you've seen them, you get familiar with the ones that can be a problem and only change those, YMMV.*Most were binned before I acquired the contents of the storeroom, following EOL of the lab, the Frako was found after.David

author: Haenk
author_rank: Super Contributor
timestamp: July 19, 2025, 09:21:09 pm
content: Quote from: factory on July 19, 2025, 08:54:51 pmHowever the Frako certainly did not suffer from that stolen, incomplete formula that let all the chinese caps pop. That's just old age, rubber seal getting tired (hard), might be still "good to use" for years (though that is not a good idea). The chinese cap plague was more like decomposing electrolytes, leading to raised pressure in the can, ultimately breaking the emergency vents on top or pushing liquid electrolyte through the not-so-tight seal.

author: factory
author_rank: Super Contributor
timestamp: July 19, 2025, 10:10:16 pm
content: Yes old age & perished seals, I don't have any pictures of the other brands that were new old stock, they were thrown away years ago.The test gear from my collection is mostly 1950s to 1990s, there is hardly any modern TE here, replacing every single capacitor is not a good use of my free timeormoney.Also haven't seen problems with no-name modern caps venting for some time, but it seemed to be a common problem around 20 years ago, newer stuff seems to be using more multilayer ceramic caps.David

author: MarkusAJ
author_rank: Contributor
timestamp: July 19, 2025, 10:46:52 pm
content: Quote from: factory on July 19, 2025, 08:54:51 pmIn my experience in the 1990s worst capacitors came from Sony. During my U time, I was making extra money repairing home electronics. In Sony's TV and VCRs electrolytic capacitors were dead in 1 - 3 yearsI'm fun of ROTEL gear (not I'm not an audiophile!) and I have few amplifiers from early 80's, I'm doing a PM every 5 years. Electrolytic capacitors in my oldestRB-870BXRA-870BX from ~ 1981 have no leaks, last checked ~2 years ago.I'm not using fancy meters, just load them with 1A current source to nominal voltage and next checking the leak with uA meter.

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 20, 2025, 05:40:41 pm
content: Quote from: Ian.M on July 18, 2025, 11:31:40 amNot only Rifa. Rifa is just well-known for loud X2 papercaps. But there is some amount of non X2 (general use) paper caps in old equipment, which to 2025 mostly are bad if don't have a proper hermetised military metal case. A cheap lavsan (PET) film works just fine instead.It's easy to distinguishe bad paper cap - it has higher than rated capacitance (+20..+40 %, up to +50..60%) and too low resistance across it (down to several kiloohms instead of megaohms++).