How to Repair Capacitors on Computer Motherboards and Other Electronic Devices.





Introduction: How to Repair Capacitors on Computer Motherboards and Other Electronic Devices.

This instructable will show you how to diagnose and repair bad capacitors on computer circuitry saving you money on new appliances and preventing landfills from filling up. 

Always unplug electronic devices before opening them!  Even after opening make shore you discharge all the capacitors with a discharge rod.

Step 1: Materials

You will need.

a Soldering iron
a cutting pliers
safety glasses
rosin core solder
the replacement capacitors
an anti static band (if your working with delicate circuitry)
a de soldering pump (optional)
and de soldering wick (optional)

Step 2: Diagnosing the Bad Capacitor(s).

You should be looking for capacitors that are bulging slightly at the top or bottom, have black, brown or white goo oozing from the top, or that are pushing themselves away from the board.

Step 3: Removeing the Capacitors

  Desolder the bad capacitor(s) from the board. Don't immediately throw the bad capacitors away, we'll need them for the next step.  Also not the direction of the gray colored band on the side of the capacitor. The new capacitor must be inserted the same way.  Wear eye protection sometimes the bad capacitors can explode because there under pressure.

Step 4: Adding the New Capacitors

The bad capacitor(s) should have markings on the side like for instance 10v 100µf.  replace the capacitor(s) With ones with the same markings.  You can use a capacitor with the same or higher voltage. But don't change the capacitance.

Step 5: You're Done

The application you changed the capacitors on should work perfectly now.



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    71 Discussions

    Thanks for the instructable. Is there any need/recommendation to also change ceramic capacitors (or other components)?

    I am delighted to know this site exits, please keep this job up. However the circuit on which the capacitors are to be changed should fully be dead or completely be discharged before replacement or repairs take place on it.


    2 years ago

    filing luckly


    Can I replace a 1000uf 6.3v for a 1000uf 10v cap? please help me ///

    many times I have done these replacements. After changing bad capacitors with a new ones all works great. If you would like to see how I done this follow my blog

    I purchased a used benchtop power supply. As soon as I plugged it in at least one capacitor popped. I am trying to evaluate whether I can repair the device by replacing the capacitor or if I will need to perform a more in depth repair. When a capacitor pops, what is the likelyhood of other components being damaged? What type of components would be most sensitive to the failure? What happens electrically as a capacitor fails? Is it equivalent to a short or an open?

    1 reply

    Capacitors are cheap. I would replace it and see what happens. Capacitors filter out ripples in the curent or noise. They basically act sort of like mini surge protectors. You may or may not have damaged somthing else when it blew.

    Great Instructable!

    Many years ago I did some research on these capacitors. It turns out some companies had stolen some designs from a Japanese manufacturer and left out some of the chemical formula. So millions of these were put into products.

    Safety: All though not a major concern, motherboards can be subject to static electricity damage. So try to ground yourself to earth ground especially when working on carpet. In the U.S. all those screws in between the AC sockets are tied to earth ground.

    The author is correct that polarity is very important. The little grey stripes indicate the negative side. And higher voltage ratings doesn't matter. The voltage rating is just the maximum voltage that can be applied to the component.

    And the author is also correct that shape and size don't matter as long as you can get it to fit and soldered.

    11 replies

    "Many years ago I did some research on these capacitors. It turns out some companies had stolen some designs from a Japanese manufacturer and left out some of the chemical formula. So millions of these were put into products."

    I've read this also, but it does not make sense.

    Would an established capacitor maker, with their own magic brew just take another formula without testing? It just does not make sense.

    My memory isn't the greatest but I believe these were foreign start up companies that were not established capacitor makers. Since they probably didn't have a design engineering staff, they could sell it cheaper then reputable companies.
    Purchasers for the motherboards, printers, etc., looked for the best price. They may have done some internal testing but, in this case, the major failures were often years down the road. I worked in the electronic reliability testing for many years and know the difficulties of finding long term failures in a short period of time. (Manufacturers can't test a product for 10-15 years before they sell it as it would be obsolete)

    As a retiree, I buy a lot of my electronics on ebay, mostly from China. Most of it has been fairly good quality but I have had some bad, especially cables, audio and USB. But when I spend a $1 or $2 for a cable, I don't expect a lot.
    As for long term reliability, I have even less expectations, but then I am old.


    That makes a lot of sense, but I believe even well established companies suffered failures.

    There is also accelerated aging (at high temperatures) to try and gauge future failures.

    You are right, well established companies suffer failures also. And there's various levels of well-established as far as quality and reliability are concerned.
    You are probably more familiar with the current state of electronic manufacturing but I suspect that 99% of electronics is manufactured overseas. Though much is probably outsourced by established companies, there is still issues of transfer of technology and quality control.
    My experience was in testing products rather than components. Heat was the primary gauge but we also used cold, high/low humidity and vibration in all axis. Another method we uses was reliability software where you input a bill of materials and estimated weakest components based on reliability data from the component manufacturers (primarily MTBF).
    In my experience, I almost never see an electronic component failure unless it was subject to static or lightning. Most of the failures I've seen are mechanical, especially fans and connectors.


    I feel certain that you know much more than myself, but I wonder if the slew of capacitor failures was not perhaps due to the higher power CPUs, and that perhaps design and solid state capacitors has finally caught up. The future trend seems like it might be headed in the opposite direction, toward lower consumption.

    Given that computers are said to consume more energy than air travel, this might not be a bad thing at all.

    In electrical terms, power is voltage times current. But if you've been following CPUs in computers, they used to be 5Vdc, dropped to 3.3Vdc and I believe some of the newer ones are 1.8Vdc. So higher power means higher current.

    These capacitors are electrolytic capacitors used to filter DC power. Current doesn't actually pass through them. That is why they only have a voltage rating and a value. So in a higher powered circuit an electrolytic capacitor may not filter as well but it wouldn't contribute to a higher capacitor failure rate.

    There is a trend to low power consumption. IMHO, this is due to lower CPU voltages and multiple cores. Multiple cores generally run at lower speeds (less power) but higher performance (because of multi-cores and other design advancements.

    By the way, I just ran across an interesting but somewhat biased website:


    But current passes into and out of them, and they have a voltage rating, a capacitance AND an effective series resistance (ESR), and when this is high, they run hot.

    So I must differ with you on this, the higher the power of the circuit, the higher the heating of the capacitor and so the faster it fails.

    I, respectfully disagree. Electrolytic capacitors in digital computers are used to filter power supplies. Just about the only current that passes through them is when the computer is turned on and the capacitor charges up to the power supply voltage. An electrolytic capacitor in a digital circuit should never get hot or even warm, no matter how high power the CPU. The only reasons I know of an electrolytic getting hot is if they are installed incorrectly (polarity) or if they are defective.

    Now I agree that electrolytic capacitors in an analog circuit can pass current. And this is important especially in AC motor circuits.

    So I would like to see any digital computer circuitry that has electrolytic capacitors that pass much current and heat up.


    Then why do they take care to use capacitors with low ESR, sometimes even less than 0.01 ohm. They pass a lot of current trying to keep the voltage constant for chips that are very variable in their current consumption.

    Out of curiosity, I had to do some more research on this.
    First, I was wrong about electrolytic capacitors not heating up in operation. They do.
    "Ripple current is the rms value of alternating current flowing through a capacitor." This means it's AC current not DC so higher steady currents don't affect it.
    Second, I believe ripple current is more of an effect of input variations than output. But output AC loading will affect it. Higher powered systems are usually running at higher frequencies which could increase ripple current so you may be right about them generating more heat. Another factor is higher powered CPUs generate more heat which will likely raise the ambient temperature of the motherboard which will also raise the temperature of the capacitors.
    Third, I think the main reason designers use capacitors with lower ESR is that lower ESRs improve their filtering capabilities.
    Full disclosure: I am speaking more in practical terms (technician) than in theoretical terms (engineer) as I do not have an engineering degree.

    So have you seen/heard of more capacitor failures in higher powered systems? Personally, speaking, I haven't seen any electrolytic capacitor failures except when I put one in backwards. In my opinion, if a motherboard is properly designed, you should see minimal failures of all components including capacitors. The only significant motherboard capacitors failures I've heard of, seem to be because of the 'bad' caps.


    Absolutely, AC current; the power supply capacitors take care of the input ripple and the mother board capacitors of the output ripple. The lower ESR will mean reduced resistive heating in the capacitor.

    In is my theory that the slew of failures was not so much due to industrial espionage as the increasing demands of high power CPUs and that designs then caught up with this by using the new solid-state capacitor technology.

    All this said after the need to recap the mother-board of a G5 iMac a couple of weeks back. I used electrolytic capacitors, and now wonder if perhaps I should have moved to solid-state types.

    Perhaps there was a bad run years back, but for me it doesn't make sense; the well established manufacturers would surely not have use an untested stolen recipe when they had their own. Hence the theory of higher power CPUs as resistive heating goes like I^2, so just doubling the speed of a chip would increase heating by a factor of 4.

    I recapped the power supplies on these machines a few years back, but one of the capacitors was not low ESR, and this failed after only 2 years; so I think low ESR is important for life.