How many years until Capacitors go bad?

Discussion about old PC hardware.

How many years until Capacitors go bad?

Postby BLockOUT » 2017-12-06 @ 01:24

1. What is the expected life in years of a motherboard capacitor?
2. Can a capacitor be bad even if it looks fine when you look at it? or always needs to be bulge?
3. Ever had a favorite motherboard and wanted to re-cap it with newer caps just in case?
4. Motherboards are full of 22uf capacitors everywhere. are those really important? or the bigger ones are the ones that give more problem?
5. I heard that after many years capacitors drain. Is that true?
6. There are some serious old electronics with giant capacitors, for example i opened a commodore64 5 1/4 floppy drive, and wow... it had huge caps in it something like 6800μF. Im wondering how many years those can last
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Re: How many years until Capacitors go bad?

Postby x0zm_ » 2017-12-06 @ 01:35

1. Depends on the brand/model/quality/usage. Hard to answer.
2. It can be bad without any physical signs. You can test it using test equipment though.
3. Yup, and done it multiple times.
4. I've personally only seen and tested problems with the larger caps, mainly for power delivery.
5. Yes.
6. Guess that answer comes down to the same-ish criteria as #1 there.

Caps are a funny thing. Thankfully they are easy to test and easy to replace with basic equipment. Something I think any retro electronics (of any kind) enthusiast should have in their arsenal. If you care about the hardware, it's good to know how to keep it running well and how to repair them instead of throwing them out. It also allows you to have a shot at bringing back "dead" hardware other people can't/don't want to fix.
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Re: How many years until Capacitors go bad?

Postby CkRtech » 2017-12-06 @ 01:46

BLockOUT wrote:1. What is the expected life in years of a motherboard capacitor?

Depends on the type of capacitor. Most people worry about life with electrolytic caps. Many can last a few decades. Some made during the capacitor plague era barely last a few years.
2. Can a capacitor be bad even if it looks fine when you look at it? or always needs to be bulge?

Most definitely yes. Looking at a capacitor won't tell you if it is still good.
3. Ever had a favorite motherboard and wanted to re-cap it with newer caps just in case?

I recently recapped an Epox BX3 for a Slot 1 Pentium III. One cap was going bad + it was from 1999, so I shrugged and recapped.
4. Motherboards are full of 22uf capacitors everywhere. are those really important? or the bigger ones are the ones that give more problem?

The smaller caps that do a bit of support aren't as important as the larger ones - like 1000uf - that are a major component of CPU power regulation. If I go to the trouble of replacing a bunch of caps on a motherboard, I usually replace them all. You'll see a difference in philosophy on this no matter where you go.
5. I heard that after many years capacitors drain. Is that true?

I have an idea of what you are asking here, but what do you mean by drain? Drain what?
6. There are some serious old electronics with giant capacitors, for example i opened a commodore64 5 1/4 floppy drive, and wow... it had huge caps in it something like 6800μF. Im wondering how many years those can last

I only have one 1541 that i have used, and I haven't really been concerned about the caps. That said - best to check up with other guys on Commodore forums when it comes to restore work and caps for those drives. You'll most likely have to deal with cleaning and alignment more than you'll have to worry about bad caps.
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Re: How many years until Capacitors go bad?

Postby firage » 2017-12-06 @ 01:55

1. Quality parts and a good design, 20-30 years no problem. Bad parts or bad designs, only a couple of years at worst.
2. Yes. You can't always tell by looking at them.
3. Yep, prepared to recap my babies. Got to have it planned for early 2000's stuff, especially.
4. The ones that are stressed most, hit with most heat and ripple, are bigger than that.
5. Electrolyte evaporates over time, they all have some finite lifespan.
6. The really big ones, like those, can be very durable.
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Re: How many years until Capacitors go bad?

Postby Koltoroc » 2017-12-06 @ 02:23

BLockOUT wrote:1. What is the expected life in years of a motherboard capacitor?t


Depends on a lot of factors. On older boards (pentium 1 and earlier) I would assume them to generally be ok enough regardless of age, unless there are weird random problems and frequent crashes in use, Everything newer I would assume 10-15 years before it gets suspect. Capacitors really don't like heat and anything semi modern produces a lot of it, and airflow tends to be a bit shit (to put it mildly) in 2000-2010 Era systems.

BLockOUT wrote:2. Can a capacitor be bad even if it looks fine when you look at it? or always needs to be bulge?t


yes, that is why people with weird issues that can't be pinned on software or a specific hardware component get the advice to recap. most people believe that caps are only bad if they are physically damaged, which is completely untrue.

BLockOUT wrote:3. Ever had a favorite motherboard and wanted to re-cap it with newer caps just in case?t


not really. I have 2 boards that need a recap but I don't care enough to actually do so. I generally do replacements if there are issues and it has been a while since I had such a problem. I wouldn't say it is a bad practice to recap stuff that you got new simply because you have no ideas what conditions the hardware was run under, but for me it is purely part of hardware diagnosis once everything else failed and I care enough to do so instead of simply replacing the board.

BLockOUT wrote:4. Motherboards are full of 22uf capacitors everywhere. are those really important? or the bigger ones are the ones that give more problem?t


they can be, but most of the time its not those that fail. 1 of the boards I mentioned above has them failed. literally EVERY electrolytic capacitor on that one has visual damage (cheap asrock from the capacitor plague era, full jackpot on that one). The bigger ones are the main culprits because they are part of the CPU power delivery. that means they are under permanent "stress" and are more import to remain within spec.

BLockOUT wrote:5. I heard that after many years capacitors drain. Is that true?t


They don't "drain" so much as simply dry out. That is why they can fail without visual signs and why they have limited shelf life

BLockOUT wrote:6. There are some serious old electronics with giant capacitors, for example i opened a commodore64 5 1/4 floppy drive, and wow... it had huge caps in it something like 6800μF. Im wondering how many years those can last


Same as all other cpas. If it is a mains rated PSU cap, I would recommend eventually to replace that, they can fail rather spectacularly. If it is on the low voltage side it likely won't matter too much.
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Re: How many years until Capacitors go bad?

Postby gdjacobs » 2017-12-06 @ 05:54

BLockOUT wrote:4. Motherboards are full of 22uf capacitors everywhere. are those really important? or the bigger ones are the ones that give more problem?


Generally these are used for either decoupling or a bit of smoothing. This is not always the case, though. On some less expensive power supplies (for example, the infamous 250W Bestec models) the line for standby power is smoothed with a relatively small electrolytic capacitor and will go badly out of regulation when the capacitor fails.

Location is often more telling than capacitor size. Caps are usually located close to a power supply which needs smoothing or a power consuming device for which noise or ripple is being eliminated.
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Re: How many years until Capacitors go bad?

Postby Jepael » 2017-12-06 @ 10:24

BLockOUT has some interesting questions, but answering them is not so simple.

There are different kind of capacitors.
By the nature of your questions, it appears you are specifically referring to electrolytic capacitors.

On top of that, there are also many different kinds of electrolytic capacitors, and each of them are best suited for a specific purpose. There are regular caps meant for general/bulk use and low ESR caps for high frequency use. In power supplies it means the general ones are for mains frequency stuff and low ESR ones for switching mode power supplies such as PC motherboard VRMs.

Any cap will eventually wear out, they cannot stand forever being used, their lifespan just is determined how much under stress they are, meaning temperature and ripple current.

But back to your questions:
1) Expected life of a motherboard is determined by the people who design it. If they are required to design a consumer motherboard, they won't design it to be operating after 20-30 years so they select components that are supposed to work the expected life of the product, whatever it is. Warranty period is a good sign of this, and in some countries there are legislations that a consumer product must be expected to have a certain life span and manufacturer is responsible even after warranty period.

2) Caps can look OK, and not work at all. They can be short circuited or open circuited or anything in between.

3) No, not really. If there is no proof the caps are bad then I won't change them just in case. I advise people not to recap everything just in case if they don't know what they are doing, because most often people don't know what capacitors are used for what purpose so which of them should be normal or low ESR or bipolar or something else. Some circuits NEED low ESR, some circuits are better with standard caps.

4) If they are there, they must be important for a purpose. If they weren't, they would be left out when manufactured to get more profits. But regarding whether they fail or not, usually smaller ones do not fail, but sometimes they fail too. These caps that are sprinkled all over for general purpose bypassing are not usually related to high ripple currents like those used for CPU or memory switching mode power supplies.

5) Electrolyte can dry so the capacitor loses its capacitance over time, yes.

6) That would be the low voltage bulk storage cap of the linear power supply, it is charged at 100/120Hz from the transformer and drained by the 12V regulator. Standard low frequency linear PSU stuff. if it ever fails it will most likely just lose capacitance and the 12V from the regulator would start become ripply before loosing regulation.

gdjacobs wrote:On some less expensive power supplies (for example, the infamous 250W Bestec models) the line for standby power is smoothed with a relatively small electrolytic capacitor and will go badly out of regulation when the capacitor fails.


But every regulator will go out of regulation when a capacitor fails, not just less expensive ones. And the capacitor may not be "relatively small" at all, because the higher the frequency of the switching mode power supply is, the less capacitance is required to go below the required voltage ripple specification. It might just be otherwise bad circuit design that stresses capacitors and all capacitors would eventually fail, or at least ones not rated for the given ripple current.
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Re: How many years until Capacitors go bad?

Postby .legaCy » 2017-12-06 @ 12:43

BLockOUT wrote:1. What is the expected life in years of a motherboard capacitor?
2. Can a capacitor be bad even if it looks fine when you look at it? or always needs to be bulge?
3. Ever had a favorite motherboard and wanted to re-cap it with newer caps just in case?
4. Motherboards are full of 22uf capacitors everywhere. are those really important? or the bigger ones are the ones that give more problem?
5. I heard that after many years capacitors drain. Is that true?
6. There are some serious old electronics with giant capacitors, for example i opened a commodore64 5 1/4 floppy drive, and wow... it had huge caps in it something like 6800μF. Im wondering how many years those can last

based on my experience:
1- they dont have a "expiration date" but i consider recapping when stability issues happens, the hardware don't work at all or when they are older than me, but i have one exception when i'm dealing with power supplies, if i dont know the age i will recap before even powering it on.
2- caps can fail without visual clues, and for testing you need to remove them, usually electrolytic caps go bad without clues, tantalum caps has a little bit of "personality " and will fail dead short causing a small explosion, however i never had lne failing on me, just the electrolytic ones.
3- never recapped a motherboard that didnt fit the criteria described in answer number 1.
4- capacitors have a wide variety of uses in electronics, it can be used for decoupling, bypass, filter, oscilate; so when dealing with stability issues even the small ones worth replacement, usually the resposible for power go bad, but the other ones can go too.
5- yup, and beware that the term leak has more than one meaning when its used to talk about caps.
6-same as answer 1.
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Re: How many years until Capacitors go bad?

Postby jaZz_KCS » 2017-12-06 @ 15:49

In terms of standard Elkos (electrolytic capacitors based on aluminium), the general rule of thumb for branded ones goes for ~6000 hrs of minimum life expectancy.

This differs greatly depending on the work temperatures they endure throughout the years, storage, etc.
Also no-one is able to state "hours of usage" correctly with their equipment, so...

Generally a good advice..: Make time once a year to open up your "belovettes" and thoroughtly test all caps with yer multimeter, as well as "take a goode whiff" around your systems. Remember: When they leak, they are long gone. Meaning that they most likely ceased their work long before that.
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Re: How many years until Capacitors go bad?

Postby Koltoroc » 2017-12-06 @ 17:16

jaZz_KCS wrote:Generally a good advice..: Make time once a year to open up your "belovettes" and thoroughtly test all caps with yer multimeter, as well as "take a goode whiff" around your systems. Remember: When they leak, they are long gone. Meaning that they most likely ceased their work long before that.


That will be useless. You can't test capacitors in circuit, you will only get garbage as results.
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Re: How many years until Capacitors go bad?

Postby gdjacobs » 2017-12-06 @ 17:44

Jepael wrote:
gdjacobs wrote:On some less expensive power supplies (for example, the infamous 250W Bestec models) the line for standby power is smoothed with a relatively small electrolytic capacitor and will go badly out of regulation when the capacitor fails.


But every regulator will go out of regulation when a capacitor fails, not just less expensive ones. And the capacitor may not be "relatively small" at all, because the higher the frequency of the switching mode power supply is, the less capacitance is required to go below the required voltage ripple specification. It might just be otherwise bad circuit design that stresses capacitors and all capacitors would eventually fail, or at least ones not rated for the given ripple current.


Just providing a practical example of how low power circuits (thus less/smaller components) can still be important for the health of computer hardware. Yes, generally all caps will be less effective at suppressing ripple when in bad health. The Bestec example is exacerbated by a bad cap presumably causing a loss of feedback control and no over voltage protection on the standby rail.

In other words, don't assume small (physical size) caps are unimportant.
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Re: How many years until Capacitors go bad?

Postby brostenen » 2017-12-06 @ 23:32

1. I have seen one extremely rare case of a little under one year, else it's 2 to +30 year's.
2. They can dry out, leak or bulge underneath instead of just bulging on the top.
3. Wanted? Yes. Done it just to be on the safe side? Never. Only recapped to repair stuff.
4. That I can not answer, as I know little about how they are build and how they physically work inside.
5. If by draining, you mean leaking, then yes. It can happen, and you can actually find this problem in Amiga's/C64's.
6. My C64 is still going strong, with the original caps. Yet they are nothing, compared to 370-400 volt caps.

Caps like this one here below, that are fun to play with, when you discharge them directly on metal... :-P

RC0132_1lot.jpg
Don't eat stuff off a 15 year old never cleaned cpu cooler.
Those cakes make you sick I tell.... (never tried though)

My blog: http://to9xct.blogspot.dk

001100 010010 011110 100001 101101 110011
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Re: How many years until Capacitors go bad?

Postby gdjacobs » 2017-12-07 @ 02:25

How about some line rated, oil cooled power transformers?
https://www.youtube.com/watch?v=gj1pkyCL75E
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